Journal of the Association of Teachers of Geology

Classroom Applications of the Microcomputer

NEWS Subscriptions & Questionnaire, Extraordinary General Meeting 8th May 1982, Extraordinary General Meeting 11 th September 1982, New Members, Council 1982-83, Conference 1982, London G.C.E. Board, London Group Meetings, Production of Geology Teaching, Field Courses: Dolgellau Youth Hostel, Specimen Exchange, British Association September 1982.

ARTICLE From Magma to Solid Rock by Calculation

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SHOPFLOOR Classroom Applications of the Microcomputer, An exercise for students at Advanced Level. . REVIEWS FIELDWORK Fieldwork Working Group Report 1980-81, On discerning the purposes of Geological Fieldwork.

LETTERS

COMMENT

INSERTS: ESSENTIAL QUESTIONNAIRE, BANKER'S ORDER and CONFERENCE DETAILS

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56 58

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SUBSCRIPTIONS & QUESTIONAIRE

Members are asked to pay their subscriptions for 1982-3 on or as soon as possible after October 1 st. The enclosed insert gives details of the new rates. The reasons for these increases are easy to see. We have held rates for four years, but, despite economies, costs of production and distribution have continued to rise, and income no longer meets costs. Members who do not pay by Banker's Order are urged to transfer to that method, using the Form provided.

At the same time a total review of existing files has been undertaken, with a view to computerising the data in due course. This move would greatly reduce the current work-load, and speed two-way communications concerning many matters. Please enable us to bring your card up to date by completing the questionniare. PLEASE RETURN COMPLETED FORM(S) TO THE TREASURER

EXTRA-ORDINARY GENERAL MEETING 8TH MAY 1982

Minutes of the E.G.M. of A.T.G., held at Park Site, College of St. Paul and St. Mary, Cheltenham at 11.00 am on Saturday 8th May 1982.

Agenda:

1. Apologies for Absence were received from Professor E.K. Walton and I.L. Norris.

2. A motion from the Treasurer, approved by Council, was proposed:

'That subscription rates be altered to take account of the changing financial circumstances of the Association'.

'That Subscription Rates be Ordinary Members £6 p.a., Student Members and Retired Persons £3 p.a., Institutional Members £12 p.a.'.

The Motion was proposed by the Treasurer and seconded by Mr. Crossley.

An amendment was proposed by Mr. Thompson and seconded by Mr. Dutton.

'That the Institutional Subscription be retained at £9, the other rates being as in the Motion'.

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In order for the amendment to be considered, it was pro­posed by Mr. Thompson, and seconded by Professor Owen, 'That Rule 6 be suspended', and this was carried by 11 votes to 1.

Mr. Thompson's amendment was re-tabled, and agreed by a large majority. The original Motion therefore failed.

The Meeting closed at 11.20 a.m.

(The necessary Notice of E.G.M. for Change of Rules is given in this journal number).

Gilbert Kelling (President ATG)

EXTRA-ORDINARY GENERAL MEETING 11 TH SEPT 1982

Notice of Extraordinary General Meeting of the Association of Teachers of Geology, to be held at Cheltenham, College of St. Paul and St. Mary, on Saturday 11 September 1982 at 8.00 pm.

Agenda: Rule Change.

Rule 6 to read:

"Members shall pay such subscriptions as may from time to time be prescribed by Council with the agreement of the Annual General Meeting.

Student Members shall pay less than the standard annual subscription, and Institutional Members, and those placing standing orders for the Journal, shall pay more than the standard annual subscription, both in ratios to be determined from time to time by Council, with the agreement of the Annual General Meeting. "

M.J. Collins (Secretary)

ERRATUM In the article by Peter Chadwick in Geology Teaching 7(1). "Earth boundedness in geological observation" the caption to Figure 2A should have read: "Density and brightness gradients" in (i) and (ii) ~ mono­cular cues to depth in the biosphere but in rock (iii) gradients in texture and/or brightness occur in a flat plane parallel surface in neutral graded layers . .. "

NEW MEMBERS

Will existing Members in neighbouring establishments please make new members welcome by making contact with them and offering advice where appropriate.

APRIL 1982 Ordinary Members CONNOLLY, Miss A-M, St. Pauls Sec. Sch, Newry, NI DERRETT, G.W.J., Brittons Sch., Rainham, Essex DILLON, J.S., John Roan Sch., Greenwich, London HEMINGWAY, J.M., Chingford Senior H.S. HERBERT, R.J.H., Medina Valley Centre, Newport, IoW PRESTON-JONES, Ms. S.B., Beaumont Leys Sch., Leicester ROBINSON, Miss A.J., St. Marys H.S., Hull VARLEY, W.E.,lIkley G.S., Yorks

Student Members HERBERT, S.M., Keele ROE, N.P., Aberystwyth

MAY 1982 Ordinary Members CLERK, Dr. D.A., Regent House Sch., Newtownards, Co. Down CUTHBER, J.A., Down High Sch., Downpatrick, Co. Down HI L L, Dr. A., Victoria College, Jersey HOLFORD, D.G., Leics. Univ. School Education LlLES, S., Cross Green Sch., Leeds POINTON, W.K., Chingford Senior H.S. SHREEVE, Dr. M.E. Kings Manor Sch., Shoreham-by-Sea WALLlS, Mrs. A.E., William Howard Sch., Brampton WATSON, C.G., Farmors Sch., Fairford, Glos. WILLIAMS, Miss D.C., Prices College, Fareham

Student Members HUNT, M.J.L., Leicester WHITTAKER, P., Colche

M.J.C.

COUNCIL 1982-83

Nominations are invited for election to Council. Three vacancies arise by normal rotation, and expiry of term of service of Ordinary Members of Council. Once vacancy exists for one year: it arose last year as a result of the change of function of members of Council, and has remained without nomination. Nominations' duly proposed and with the candidate's written agreement (see Rule 12), should be sent to reach the Secretary as soon as possible (not later than the A.G.M.).

M.J.C.

LONDON GCE BOARD

The Subject Reports by Chief Examiners at 0 and A Level for the 1981 exams have recently been published. Subject teachers of Schools which entered candidates should ensure that they get their copy from their School Examinations Officer.

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CONFERENCE 1982

REQUEST FOR EXHIBITS FROM MEMBERS Members are invited to offer small exhibits for display at the Cheltenham Conference. These may be displays of students' work or be concerned with teaching strategies or resources which members have developed over the years. Last year one of the most successful exhibits was concerned with a series of simple but effective sedimentation experiments based around a single sink.

Please write to Mr P.W. Williams, 2 Kingsway, Northwich, Cheshire.

D.S.T.

LONDON GROUP MEETINGS

8th and 9th October. "The Chalk" - a course for teachers to be arranged by Dr. lan Jarvis. A lecture day followed by a day in the field.

Wednesday 20th October Micropalaeontology a practical evening session for teachers who will be bringing students on the half term course or anybody interested.

Monday 25th October Micropalaeontology a day course for students at A level.

Monday 25th October and repeat on Tuesday 26th October A day course on 'MOON ROCKS' for students and teachers. There will be a short introductory session followed by practical sessions for the study and investigation of thin sections and HAND specimens.

For details of courses run at the Polytechnic and field trips please contact Bob Standley, City of London Polytechnic, Geology Department, Bigland Street, London El 2NG.

Evening meetings are held at the Geology Department, C.L.P. Meetings begin at 6.00 pm but the Swap Shop of geological specimens is open from 5.30 pm. Light refreshments are available.

PRODUCTION OF GEOLOGY TEACHING

After being produced in Bristol by Andrew Mathieson of Bristol Museum for the last two years, the assembly of Geology Teaching 6(5) and 7(1) was carried out under the enthusiastic direction of Dr Bob Standley of the Geology ·Department, City of London Polytechnic, Walburgh House, Bigland Street, London El 2NG.

The Association wishes to thank Andrew Mathieson most deeply for the enormous personal efforts he made on behalf of the Association at times when problem after problem seemed to threaten the very lifeblood of the Journal. The Council wishes Bob Standley and his team a long and happy trouble-free reign and invites members to write to him with helpful suggestions concerning the presentation of items.

D.S.T.

FIELD COURSES: 1982 DOLGELLAU YOUTH HOSTEL

July

July August

September

2-4 MOUNTAIN AND DOCUMENTARY PHOTOGRAPHY with Peter Sheppard, on location around the Moelwyns and Blaenau Ffestiniog.

9-11 INTRODUCTION TO SOIL SCIENCE Examining soil profiles, analysis and soil mapping.

16-18 A·LEVEL GEOMORPHOLOGY

31-7

13-15

20-22

27-29

17-19

24-26

(In conjunction with YHA Adventure Holidays) GEOLOGY IN NORTH WALES. An introduction to the geology of North Wales for beginners and O·level students.

A·LEVEL GEOMORPHOLOGY

A·LEVEL GEOLOGY

OLD MINES OF MID-WALES

INDUSTRIAL ARCHAEOLOGY OF THE VALE OF FFESTINIOG with Dave Wordingham: Studying the development of slate quarrying, the Ffestiniog Railway and the port of Porthmadog.

SOIL SCIENCE

October 1-3 WELSH MINES CONFERENCE in con· junction with the Welsh Mines Society. Lectures by geologists and historians involved in research on slate and metal mines in North Wales.

22-24 A·LEVEL GEOLOGY

29-31 O-LEVEL GEOMORPHOLOGY

For further details contact: Graham Hill, Kings, Dolgellau, Gwynedd, LL40 HB. Telephone: (0341) 422392.

SPECIMEN EXCHANGE

Swap good conditioned Tertiary Gastropods, Bivalves, etc from BARTON. Tertiary Pyritized Gastropods, Bivalves and Perfect Sharks Teeth from Gosport. Jurassic Ammonites Belemnites, Bivalves, Crinoids, Worm Tubes from Dorset~ Wanted, Palaeozoic and Mesozoic Fossils, especially good Trilobites, Corals, Brachiopods, Cephalopods and MOST MINERALS.

S.D. Frampton, 79 Mayfield Road, Gosport, Hants.

BRITISH ASSOCIATION: GEOLOGY SEPTEMBER 1982

The Annual Meeting of the British Association for the Advancement of Science will take place at the University of Liverpool, 5-10 September 1982. The programme of SECTION C (GEOLOGY) is particularly exciting and should interest a great many members of ATG:

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Tuesday 7 September GEOLOGY AND GOVERNMENT

PRESIDENTIAL ADDRESS: Professor J. Sutton, F.R.S., (Imperial College, London and a former President of ATG). Geology and Government. J.D. Mather (LG.S. Harwell). Research into the disposal of waste to geological formations - a case study of the involve­ment of geologists with government. J.L. Knill (Imperial College, London). Engineering geology and government. R. Macrory (Imperial College, London). Caught in the cross­fire - geologists and the law. P.T. Warren (Royal Society). Science (Geology) and govern­ment: the provision and receipt of advice.

Wednesday 8 September THE FOSSIL RECORD AND EVOLUTION

. J. Maynard Smith (University of Sussex). Neo-Darwinism. N. Eldredge (American Museum of Natural History). Pattern and Process in Evolution. L.B. Halstead (University of Reading). Pattern and Process in Evolution. M.E. Howgate (University College, London). Marxism and evolution - the new synthesis. M. Ridley (University of Oxford). Palaeontology and the evidence for evolution. M. Ruse (University of Guelph). Recent evolutionary con­troversies.

Thursday 9 September THE ROLE OF THE AMATEUR IN GEOLOGY

John Fowles (Lyme Regis). The Fossilists of Lyme. G.P. Black (Nature Conservancy). Amateur geologist and conservation. J.M. Hancock (King's College, London). Contributions of the amateur in geology. S.P. Wood (University of Glasgow). Professional-amateur relationships, a personal view. DARWIN LECTURE: A.C. Scott (Chelsea College). The early history of life on land.

Friday 10 September THE GEOLOGY OF THE SEAWAYS TO LIVERPOOL

E.W.S. Simpson (University of Cape Town). Today's research on the ocean floors. J.K. Leggett (Imperial College, London). From Mid-Atlantic to Liverpool - a submarine geotraverse. B.N. Fletcher (LG.S. Leeds). Geology of the offshore approaches to Liverpool.

For further details write to: Dr. L.B. Halstead, Department of Geology, University, Reading, RG6 2AB.

From Magma to Solid Rock by Calculation

Chris King introduces another series of exercises which he has used successfully with large groups of sixth formers. In this case he is concerned to have students demonstrate their understanding of the process of petrogenesis.

Introduction To understand igneous rocks students must understand the major processes which take place during crystallization from magmas. Perhaps the ideal way of studying these processes would be to cool a real magma in the laboratory and to monitor the processes taking place and the results. As this is not practicable, the best alternative is to simulate a cooling magma by calculation. Such calculations may be very complex and involved but if the chemistry is kept simple then the calculations are simple. We must remember, of course, that our starting point is the chemical analysis of a rock which rep­resents a solidified magma.

Teacher's Notes 1. The same method of calculation may be used with

different sets of data for different magmas. Thus the method of calculation is explained to students on a 'Method Sheet' and the data for two different magmas (one basic and one silicic) is given on a 'Data and Guide Sheet' for each magma type.

2. These calculations have been used successfully in an 'A' level course. They are simple, if rather time-consuming, and should not be attempted without the use of calcu­lators.

3. The less involved basic-melt calculation was used as a 'bridge' between courses on mineralogy and igneous rocks and in the introduction to igneous processes. This calcula­tion with the follow-up material takes about 2 hours to complete. The more involved silicic melt calculation was used as a 'bridge' between the courses on igenous rocks and the economic mineralogy by asking 'What happens to the left over ions?' etc. This calculation again takes about two hours to complete.

4. As the calculations are rather involved, it was necessary to guide students carefully through the 'first moves', but when they understood the method they completed the calculations very quickly. They also gained much from a careful analysis of their work, which had to be carried out in order to complete the section involving the tabulation of results.

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5. The 'Method Sheet' appended below is followed by two 'Data and Guide Sheets'. Suggested answers are given at the end of the article. These student worksheets, as in previous articles in Geology Teaching, are surrounded by black lines in order to indicate to teachers which parts of the article to xerox for direct use by students.

6. The author stresses that his calculations represent a hypothetical or idealised course of crystallisation and hence are not necessarily directly related to the mode, which is the real mineral composition of the rock deter­mined by observation and measurement (see later). Moreover, strictly speaking, they are not calculations of the 'norm' of orthodox petrology since these are derived from molecular proportions, not simply weight per­centages of oxides. The equating of ions and oxides for simplicity is a considerable approximation.

7. Students should realise too, that, the chronological order in which ions enter lattices to form crystals (and hence the order in which they are used in the calculations) result from their different sizes and charges, and what structures are stable at given temperatures and pressures.

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From Magma To Solid Rock - By Calculation

METHOD SHEET

As magmas (molten rocks) cool crystals form. Different minerals crystallise at different temperatures so that when the magma has cooled enough to become solid it is composed of a number of minerals in different proportions. If we wanted to find out what minerals form in what proportion we could do an experiment by taking a magma, cooling it and then analy­sing it carefully. However a much more convenient method is to do a simulation of the cooling and crystallizing process by calculation.

Method To predict the mineralogy (ie. what minerals are present and in what proportions) of an igneous rock that is most likely to form from a given magma we must know the following:

a The chemistry of the magma

b The minerals which that magma is likely to form on cooling

c The order of crystallization of the minerals

d The chemistry of the minerals which would form.

These calculations can be very complex, for various reasons which will be considered later. However if certain assumptions are made then the calculations can produce satisfactory results. The same method of calculation can be applied to any type of magma.

A. The chemistry of the magma The elements in a magma will be present in the form of ions (particles with positive or negative charges) and it is these ions which will be involved in the crystallization process. However chemical analyses are usually stated using oxides rather than ions and this convention will be used throughout the calcu­lations.

The chemistry of the magma will be given to you on the Data and Guide Sheets (see later). The figures given are hypothetical but possible.

B. The minerals which the magma is most likely to form on cooling

By observation of igneous rock textures and by experiment with igneous melts N.L. Bowen showed which minerals crystal­lize at which temperatures in a cooling magma. He published his results in 1928 as 'reaction series' now called Bowen's Reaction Series, as follows:

Qlovme

\ Pyroxene

\

Mmeral~ with' Low Percentage of SI

Amphlbole

O'J-""l

low Temp

\ "i'lOo.,"'OCI'"

K Feldspar

..l. MUSCOVite

J. Quartz

Mmeralswlth High Percentage of SI

Note that Ca 1 00 plagloclase contains 100% Ca and 0% Na etc

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n PR

Chemistry as well as temperature is important in this series. In general, those minerals at the top of the series are poor in silicon (Si) and those near the bottom are rich in Si, as shown in the diagram.

Thus basic magmas (poor in Si) form minerals near the top of the series and silicic magmas (rich in Si) form minerals near the bottom of the series. The Data and Guide Sheet tells you how to work out what minerals to expect from your magma.

C. The order of crystallization of the minerals Those minerals near the top of Bowen's Reaction Series will be the first to crystallise, those near the bottom last and some minerals will crystallize at the same time as others. For the purposes of this calculation we have to assume that the minerals will crystallize in turn and that all of one mineral will crystallize before the next begins to form. Using this infor­mation and the Data and Guide Sheet, work out the order of crystallization of minerals from the magma.

D. The chemistry of the miinerals which would form In many of the major rock forming minerals the chemistry can vary so a 'typical' chemistry has been chosen for each mineral to make the calculation possible (eg. olivine can range from an end member containing mostly iron (Fe) with some magnesium (Mg) to an end member containing mostly Mg with some Fe. The chemistry you have been given below in Table 1 is for an Mg:Fe ratio of 1:1).

Given this information and the information of the Data and Guide Sheets you are now ready to proceed with the calcu­lation. To remind you - the object of the calculation is to say how much (%) of each rock-forming mineral would be present in the rock produced by cooling of the given melt. Conclusions may then be drawn from the figures produced.

Procedure Do the following calculation for each of the minerals in turn in the order that you have listed them. You are given the calcu­lation for Ca100 plagioclase (the first mineral likely to crystal­lize) as an example. We must assume that crystallization of the Ca100plagioclase removes all the CaO.

Calculate:

a what percentage of Ca100plagioclase forms from the magma;

b what percentage of each of the ions present does the Ca100plagioclase remove from the magma;

c what percentage of each of the ions present remains in the magma.

The Data and Guide Sheets which follow show you how to do this and how to record your results.

When you have calculated how much of each of the ions present remains, check the new assumptions to make, then repeat the calculation for the next mineral to crystallise. Then repeat the procedure for the remaining minerals . Results 1. The mineralogy of the rock most probably formed by

the crystallization of the magma has been calculated. This should be stated as: 'The resultant rock contains the following minerals, Ca100plagioclase x%, next mineral Y%, etc:

TABLE 1

MINERAL Percentage of Oxide contained in Mineral

Si02 AI203 Fe"O MgO

Olivine (Mg:Fe=l: 1) 34 0 32 32 pyroxene (Mg:Fe=l:l) 50 0 23 23 Amphibole (Mg:Fe=l:l) 45 12 11 Biotite (Fe rich) 37 14 32 Cal00Plagioclase 44 36 0 Nal00Plagioclase 68 20 0 Potassium Feldspar 63 20 0 Muscovite 45 39 0 Quartz 100 0 0

2. Having completed the calculation, you should understand the following things better:

a Minerals are chemical compounds of several elements.

b Most major minerals contain Si and 0 in various pro-portions.

c Igenous rocks are composed of several different minerals.

d Minerals crystallize from a magma in a certain order, from high temperature to low temperature minerals.

e The types of minerals that crystallize depend upon the chemistry of the melt, not usually the temperature or speed of cooling of the magma.

f Crystallization is a 'mopping up' process and as crystal­lization continues each of the major elements is 'mopped up' in turn.

g The quantity of a mineral formed during crystallization may depend upon the types and quantities of minerals that have already crystallized.

h Only very rarely in exceptional circumstances do all the minerals in Bowen's Reaction Series occur in one igenous rock.

The shapes of minerals formed depend upon when they crystallised. First formed minerals can grow with­out hinderance and so have good (euhedral) crystal shapes. Last formed minerals just have to fill in the gaps and so have poor (anhedral) crystal shapes.

Melts, rocks and minerals contain only a small number of major elements, ie. 0, Si, AI, Fe 11, etc.

If you still do not understand any of these important points then ask. If you cannot remember them then write them down.

3. You have calculated the possible mineralogy for a particular magma chemistry. If the types and quantities of mineral formed by cooling a magma are found by examination of the rock itself then the result is called the 'mode'. If the measured 'mode' and the calculated mineralogy differ then some of the assumptions made in calculating the mineral content must have been inaccurate. So in this way we can test the assumptions or hypotheses we make.

Go through the Method Sheet and the Data and Guide Sheets and list all the assumptions you made.

Other factors which may have major effects on the final products of crystallization but which have been ignored for the sake of the calculation are:

11 4 0 0 0 0 0

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CaO Na20 K20 H2O Others, Total ego Ti02

0 0 0 0 2 100 0 0 0 0 4 100

12 1 1 2 5 100 0 0 8 4 1 100

19 0 0 0 1 100 0 12 0 0 0 100 0 0 16 0 1 100 0 0 12 4 0 100 0 0 0 0 0 100

a Several minerals may crystallize at the same time.

b All the minerals, with the exception of quartz, have a variable chemistry. Some minerals have solid solution series, ie. their chemistry can vary progressively between fixed boundaries, the 'end members' of the series. Thus olivine can vary from Fe rich to Mg rich.

c Some minerals crystallize at faster rates and thus their crystals grow faster than others.

d Some minerals are better at 'attracting' the ions they require than others.

e Many minerals react with the melt as it cools and this may have an important effect on the resultant miner­alogy. (Minerals which have reacted thus and been partially resorbed can sometimes be seen in lavas).

f The present or absence of other ions in small (or 'trace') quantities may have great effects.

g The pressure at which cooling takes place can be a crucial factor. This is not likely to be so for magmas within the upper crust but becomes increasingly sig­nificant as we pass into the lower crust and mantle. For example, plagioclase crystallization is inhibited by high pressure.

h If the volatiles (H20, etc) are allowed to escape then the viscosity of the magma will increase, retarding the movement of ions.

Conditions of pressure, temperature, viscosity, chemistry, etc. are likely to vary considerably through­out a single cooling body of magma.

(i) Country rocks absorbed into the magma will change the chemistry of the latter. However, amounts of such additions are small and confined to the outer parts of intrusions.

Oi) Massive, impermeable and unfractured country rocks will exert higher confining pressure than those which liquid and vapour can penetrate easily.

(iii) Permable country rocks will allow the escape of volatiles (those elements and compounds which remain fluid to low temperatures).

4. Now see the Data and Guide Sheets.

FROM MAGMA TO SOLID ROCK - BY CALCULATION DATA AND GUIDE SHEET 1

Crystallization Of A Basic Magma

A. The chemistry of the basic magma

Table 2

Ions Present (given as Oxides)

Si02 (silicon oxide)

AI 203 (aluminium oxide)

FellO (ferrous (= iron) oxide)

MgO (magnesium oxide)

CaO (calcium oxide)

Percentage in Magma

45.4

17.4

12.7

12.7

9.2 R .. . ( F"IO T'O emammg Ions ego 2 3' I 2'

P 205' CO2, etc. 2.6

100.0 Total

B. The minerals which the basic magma ia most likely to form on cooling

A basic magma of the chemistry given is the most likely to crystallize the three minerals at the top of Bowen's Reaction Series. Write down the names of these three minerals.

C. The order of crystallization of the minerals In a magma of this composition, Ca1QOplagioclase will crystal· lize before olivine. Work out and write down the order of crystallization of the three minerals.

D. The chemistry of the minerals which would form The 'typical' chemistry of the minerals in Bowen's Reaction Series is given on the Method Sheet. The only minerals that you will be interested in are the ones you have listed.

Procedure

a. What percentage of Ca 1 ooplagioclase forms from the magma?

Ca 100 plagioclase removes all the CaO from the magma = 9.2%. But the Ca 100 plagioglase also removes other ions. The percentage iJf total ions removed by the Ca 1OrP'agioclase is calculated as follows:

Ca 1o(jJ'agioclase takes

%CaO in magma x 100 %CaO in Ca 1(Xp'agioclase

= 9.2 x 100 19

= 48.4 % of all ions in magma

% of all ions

Thus the crYstallization of the Ca10rP'agioclase removes 48.4% of the magma.

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b. What percentage of each of the ions present does the Ca100 plagioclase remove from the magma?

We calculate the percentage of Si02 removed by the Ca 1o(jJ'agioclase as follows:

Ca 1o(jJ'agioclase takes

(% of all ions in magma) x

(% Si02 in Ca 100 plagioclase) % of Si02 100 in magma

- 48.4 44 213% fS'O . - x _ = . 0 I 2 In magma 100

The same calculation is done for the other ions as follows:

Ca 1o(jJ'agioclase takes 48.4 x 36 % AI..n 100 :r3

= 17.4% of AI#3 in magma

Ca 100plagioclase takes 48.4 x 0 % Fe"O

100

= 0% of Fe' 'Oin magma

Ca 100 plagioclase takes 48.4 x .!!.. %MgO

100

= 0% of MgO in magma

Ca 100 plagioclase takes all the Cao in magma

= 9.2% of CaO in magma

Ca100plagioclase takes 48.4 x _1 % others

100

0.5% of others in magma

c. What percentage of each of the ions present remains in the magma?

Since we now know how much of each ion the Ca1rxP'agioclase has 'mopped up' we can find how much is left by simple subtraction from the original quantity.

e.g. quantity of Si02 remaining

= original quantity - amount taken by Ca 100Plagioclose

= 45.4 - 21.3

= 24.1%

d. The percentage of ions remaining should be tabulated (Table 3) for later use. Copy the table below in which the ions taken by the Cal ooplagioclase have been subtracted. You will need to complete the blank columns as you continue the calculation.

Table 3

e. Now repeat the calculation for the two other minerals in order assuming that:

1. Olivine removes 25% of the MgO

2. pyroxene removes the remainder of the MgO

Results 1. State the mineralogy of the hypothetical rock as shown on

Table 1 on the Method sheet.

2. Re-read and reconsider the points made under the heading 'Results' on the Method sheet.

3. List the assumptions you have made during the calculation, add to this list the other assumptions that were made, using the 'Other factors ... ' section of the Method sheet.

4. You have now completed the calculation and consideration of results for a basic melt. You should realise that in nature most melts will be more complex than this, and they will involve more ions and the formation of more minerals.

Percentage of ions remaining after these minerals have crystallized Ion ( = oxide)

Original After Cal00plagioclase After Olivine After Pyroxene

Si02 45.4 24.1

AI 203 17.4 0

Fe 0 12.7 12.7

MgO 12.7 12.7

CaO 9.2 0

Others 2.6 2.1

In response to requests from ATG members, the Promotions Group have acquired a range of new items for sale, in addition to the slide sets already available.

• .TARR'S WORLD SEISMICITY MAP* £1.50 (plus 50p for p & p) Depicts magnitude, depth and date of the world's major earthquakes. (Size approximately 90 x 120 cm).

• OPEN UNIVERSITY EVOLUTION CHART* £1.50 (plus 50p for p & p) Illustrates evolution of major faunal and floral groups through geological time. (Size approximately 75 x 110 cm).

• USA STATE GEOLOGICAL MAPS** £1.00 (plus 20p for p & p) A set of 10 coloured geological maps of individual states, some with cross-sections and stratigraphic columns. (Size approxi­mately 30 x 40 to 50 x 55 cm).

• GRAIN SIZE SCALE 20p each (plus 20p for p & p) 15p each for 20 copies or more (plus 20p for p & p) 100 copies or more (post free) Specially printed for ATG in red and black on white plastic card. (Size 6 x 9 cm).

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• ATG TIE £3.40 (plus 30p for p & p) Blue cloth tie with ATG motif

• SLIDE SETS Detailed descriptions given in GEOLOGY teaching Vol. 6 (2) p.42.

Folds £2.50 (plus 25p for p & p) 10 slides with notes.

Intrusive Igneous Field Relationships £2.50 (plus 25p for p & p) 10 slides with notes.

* map and chart send folded flat - if you would like them rolled please send cardboard tube.

** Members who have purchased the set of 8 can obtain the other 2 maps FREE. Please send a large s.a.e.

Orders to Steve Flitton, Geology Department, Worthing Sixth Form College, Bolsover Road, Worthing, Sussex

Cheques and postal orders shou Id be made payable to The Association of Teachers of Geology

Orders received in August may be subject to a short delay.

I r llnllll r ii

FROM MAGMA TO SOLID ROCK -BY CALCULATION Data and Guide Sheet 2

CRYSALLlZATION OF A SILICIC MAGMA

A. The Chemistry of the acidic magma

TABLE 4

Ions Present (given as oxides)

Si02 (silicon oxide)

AI~03 (aluminium oxide)

Fe '0 (ferrous oxide)

MgO (magnesium oxide)

CaO (calcium oxide)

Na20 (sodium oxide)

K20 (potassium oxide)

H20 (water)

Other ions (eg. Fe~"03' Ti02, P205' CO2, etc)

Total

B. The minerals which the silicic magma is most likely to form on cooling

An acid magma of the chemistry given is likely to crystallize minerals near the bottom of Bowen's Reaction Series. Assuming that both Ca100plagioclase and Na100plagioclase will crystallize and no 'mixed' plagioclases will form and also that no amphibole will form, write down the names of the minerals that will crystallize.

C. The order of crystallization of the minerals Work out the probable order of crystallization of the minerals from Bowen's Reaction Series (remember we are assuming that only Ca 1 OOplagioclase or Na 100plagioclase can form). List the SIX minerals in order of their crystallization.

D. The chemistry of the minerals which would form This is given on the Method Sheet. The only minerals that you will be interested in are the ones which are listed.

Procedure a. What percentage of Ca100plagioclase forms from the

magma?

Ca1orPlagioclase removes all the CaO from the magma = 1.3% The percentage of total ions removed by the Ca 1orPlagioclase is calculated as follows,

Ca 1orPlagioclase takes

%CaO in magma x 100 % of all ions -------------------= 1.3 x 100

19

%CaO in Ca 100 plagioclase

= 6.8 % of all ions in magma

Thus the crystallization of the Ca 1OcPlagioclase remo ves 6.8% of the magma.

46

Percentage in Magma

69.5

15.0

1.8

0.2

1.3

2.9

3.4

4.1

1.8

100.0

b. What percentage of each of the ions present does the Ca100plagioclase remove from the magma?

We calculate the percentage of Si02 removed by the Ca 1orPlagioclase as follows:

Ca 1orPlagioclase takes

(% of all ions in magma) x (%Si02 ;n Ca10cPlagioclase

100

% of S;02 in magma

= 6.8 x 44

100

= 3.0 % of Si02 in magma

The same calculation is done for the other ions as follows:

Ca1orPlagioclase takes 6.8 x 36 % AI#3 100

= 2.4 % of AI#3in magma

Ca 1orPlagioclase takes all the CaO in the magma

= 1.3 % of CaO in magma

Ca1orPlagioclase takes 6.8 x _1 % others 100

= 0.1 % of others in magma

Ca 1JX!llagioclase takes none of Fe" 0, MgO, Na #' K #' or H 2' trom the magma.

c. What percentage of each of the ions present remains in the magma?

This is found by simple subtraction from the original quantity.

ego quantity of Si02 remaining

= original quantity - amount taken by Ca l()(plagioclase = 69.5-3.0 = 66.5 %

d. Tabulate the percentage of ions remaining using a copy of Table 5 below. You will need to use this table later.

Table 5

Ion (= Percentage of ions remaining after these minerals have crystallized

oxide) Original Ca 1 ooplagioclase biotite

Si02 69.5 66.5

AI 203 15.0

Fe ° 1.8

MgO 0.2

CaO 1.3

Na20 2.9

K20 3.4

H2O 4.1

Others 1.8

e. Now repeat the calculation for each of the other minerals in order assuming that:

1. Biotite removes all the Fe"O 2. Na1 ooplagioclase removes all the Na20 3. K feld. removes 66.67% of the remaining K20 4. Muscovite removes all the remaining K20 5. Quartz removes all the remaining Si02

Results 1. State the mineralogy of the hypothetical rock as shown on

Table 1 of the Method sheet.

2. Re-read and reconsider the points made under the heading 'Results' on the Method sheet.

3. List the assumptions that have been made (if you have not done so already).

4. The 'average' composition of the 'mixed' plagioclase (ie. plagioclase with y% Ca and z% Na) that would form is calculated as follows:

The ratio of %Na1ocPlagioclase; %Ca10cPlagioclase

= x ; 6.8

Thus the % Ca in 'mixed' plagioclase .!.:!.. x 100 = Y x+6.8

And the % Na in 'mixed' plagioclase = ~ x 100= z 6.8+ x

Thus the 'average' 'mixed' plagioclase would be Na Ca plagioclase. Calculate what y and z are for the plagio~las~ crystallized from the magma.

47

Na100plagioclase K feld muscovite quartz

I n fact the majority of plagioclase found in rocks is 'mixed' plagioclase. Write down why you think this is so.

5. The calculation gives the percentage of ions 'left over' when crystallization of the main rock forming minerals is completed. These figures may be read directly from the end column of the table you have copied and completed. They should be stated in a sentence as:

The remining ions (expressed as oxides) are x% H20, etc.'

6. The calculation shows that an acidic magma on crystal­lization may well produce a remaining fluid rich in compounds with low freezing points (called volatiles) such as H20, CO2, etc. Write down what you think will happen to this final magma rich in volatiles.

7. The remaining fluid may also be very rich in elements which were only present in the original magma in small quantities. These are called 'trace' elements. Write down why you think they are so-called. Also write down what you think will happen to these trace elements after the greater part of the magma has crystallized.

8. Quartz is often found as a gangue (ie. non-economic) mineral associated with ore deposits. Explain why you think this is so.

9. Calculations similar to the one you have completed are important in the study of igneous magmas and rocks. Write down why you think that they are important both by making reference to the sheets you have used and by adding ideas of your own.

----------------------------------""' .. _-------------_ .. ANSWER TO THE PROBLEMS SET

(a) THE BASIC MAGMA CALCULATIONS The completed table in section c of 'Procedure' should be as follows:

Table 3 (completed)

Percentage of ions remaining after these minerals have crystallized Ion (= oxide)

original after Ca 100plagioclase after olivine after pyroxene

Si02 45.4 24.1

Al 203 17.4 0

FeO 12.7 12.7

MgO 12.7 12.7

CaD 9.2 0

others 2.6 2.1

The statement of the basic rock mineralogy should read, The resultant rock contains the following rock forming minerals, Ca1OcPlagioclase, 48.4%, o/ivine, 10.0%, pyroxene 41.3%.'

(b) THE SILICIC MAGMA CALCULATION The completed table in section c of 'Procedure' should be as follows:

Table 5 (completed)

20.7

0

9.5

9.5

0

1.9

Ion (= Percentage of ions remaining after these minerals have crystallized

oxide) original Ca 1 ooplagioclase biotite

Si02 69.5 66.5 64.5

Al203 15.0 12.6 11.8

Fe 0 1.8 1.8 0

MgO 0.2 0.2 0

CaO 1.3 0 0

Na20 2.9 2.9 2.9

K20 3.4 3.4 3.0

H2O 4.1 4.1 4.0

others 1.8 1.7 1.6

The statement of the silicic rock mineralogy should read, The resultant rock contains the following rock forming minerals, Ca 1ocPlagioclase, 6.8%; biotite, 5.6%; Na 10rPlagioclase, 24.2%; potassium feldspar, 11.9%; muscovite, '0.0%; quartz, 36.0%.' (Notes that these percentages only total 94.5, as the 'remaining ions' have not been considered. To be completely accurate the results should be recalculated 1'W0 100% by multiplying each percentage by a factor of - or 1.06).

94.5

Na 1 ooplagioclase K feld muscovite

46.5 38.6 34.1

6.5 4.0 0.3

0 0 0

0 0 0

0 0 0

0 0 0

3.0 1.0 0

3.7 3.7 3.3

1.6 1.5 1.1

48

0.0

0.0

0.0

0.0

0.0

0.2

quartz

0

0.3

0

0

0

0

0

3.3

1.1

c. The answers, or possible answers, to the questions posed in relation to the results gained from the silicic magma calculations.

These are as follows:

4. The 'average' 'mixed' plagioclase is Na80Ca20plagioclase. That is a Na:Ca ratio of 79.5 : 20.48 or 80:20.

5. The statement about the remaining ions should read: 'The remaining ions (expressed as oxides) are 3.5% H;I1: 0.5% AI;I1:i 1.5% others:

6. The final melt, rich in volatiles, has a viscosity and density much less than the parent magma and thus it migrates outward and upward along any permeability paths available, mixing with groundwaters and cooling with crystallizing as it goes.

7. The trace elements are deposited together with gangue minerals, along the permeable migration paths provided by joints, faults or permeable beds. Thus they form mineral veins, mineralised faults and fault breccias or disseminated ore deposits.

8. Quartz is often found as a gangue mineral because the 'remaining fluid' usually migrates away from the parent magma before all the silica has crystallized. Thus quartz deposits with other ore minerals during the stages of the final cooling of the magma.

9. The importance of the calculations are:

(a) to test assumptions made by students in calculating 'norms'.

(b) to illustrate the fractional crystallization process.

(c) to show how volatile rich and trace element rich magmas occur.

(d) to relate magma chemistry, mineralogy and economic mineralogy together.

(e) to suggest that the calculation can be reversed to work out the composition of the parent magma from a rock of known mineralogy.

(f) to suggest that the reversed calculation can also be used to work out how the composition of a magma changed during different phases of intrusion.

(g) to imply that by using 'standard minerals' the petro­logist can use the reversed calculations to compare suites of rocks and distinguish trends over large areas or vast time-scales regardless of local variations.

ACKNOWLEDGMENTS I would like to thank Colin Exley and George Rowbotham fol' their valuable criticisms of various versions of this article and for many suggestions for improvement. I would also like to thank the Editor for his help and encouragement through what has turned out to be a lengthy period of gestation.

Chris King, Department of Geology, Altrincham Grammar School for Boys, Marlborough Road, Altrincham, Cheshire.

49

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Classroom applications of the Microcomputer INTRODUCTION Like all sciences, geology can be well served by the application of computers as teaching aids to all levels. Using BASIC computing language it is possible for the geology teacher, with only a little training, to write his own programme as aids to both quantitative and descriptive aspects of the subject. The programmes listed here were written for use on the Sinclair ZX80, and later the ZX81, micro-computer without any previous formal training. The techniques used are easily adaptable to other BASIC machines and the listings will give some help to those wishing to begin their own pro­gramming.

Quite apart from their value as teaching aids, the programmes offer computer experience to pupils who might otherwise not have the opportunity to use them, and raise a number of follow-up questions concerning both the nature of the geo­logical phenomena being studied and techniques of statistical analysis and presentation.

AN INTRODUCTORY PROGRAMME INVOLVING THE IDENTIFICATION OF MINERALS An appropriately simple introduction to computer pro­gramming and classroom application is shown in figure 1. This programme was written by sixth-form pupils for use with a CSE class. It asks pupils to observe and test, one by one, ten different mineral specimens (those specified by the WMEB West Midlands Examining Board syllabus) and responds to their answers by identifying the mineral. The starting point for writing this programme was a flow diagram (see figure 2) which shows the step-by-step elimination needed to identify the specimen being tested. Construction of the flow diagram, which is an important first step in all programme writing, was in itself a useful exercise for sixth-form pupils, benefitting both their mineralogical and programming knowledge.

The structure of the programme after line 50 is a series of four-line units, each dealing with a separate mineral. The first two of these units is shown in figure 1 (lines 60 to 130) and, using the flow diagram, it is easy to see how the pro­gramme continues for the remaining 8 minerals (to line 430).

A more sophisticated version of this programme is shown in figure 3 where the questions in the flow diagrams are entered

r 1

10 REM CSE MINERAL IDENTIFICATION 20 PRINT "CHOOSE A SPECIMEN" 30 PRINT 40 PRINT "ANSWER QUESTIONS Y OR N" 50 PRINT 60 PRINT "EFFERVESCES IN ACID?" 70 INPUT AS 80 IF AS = N THEN GOTO 100 90 IF AS = Y THEN PRINT "CALCITE"

100 PRINT "SALTY TASTE?" 110 INPUT AS 120 IF AS = N THEN GOTO 140 130 IF AS = Y THEN PRINT "HALITE"

continue this sequence for the remaining 8 minerals, using the flow diagram, up to line 430 then continue as below:

440 IF AS = Y THEN GOTO 480 450 IF AS = N THEN PRINT "YOU HAVE MADE A MISTAKE"

460 PRINT "START AGAIN" 470 GOTO 60 480 STOP

Fig 1

deleting them while running the programme, the user should press GOTO 130 rather than use the normal RUN function.

Although the information held in the programme is not of the complexity which demands the use of a computer, this proved to be a novel and informative way of encouraging CSE pupils to test mineral specimens and at the same time to use a computer keyboard.

FURTHER EDUCATIONAL ADVANTAGES OF USING COMPUTERS The value of computers in handling numerical data lies in their ability to store and process a large number of variables in a fraction of the time possible by other means. Less time is therefore spent on laborious calculations and more on analysing the significance of results. It becomes possible to undertake exercises which otherwise would not be considered and to collect field data in quantities which allow statistical analysis within acceptable confidence limits.

at line 50 as an array and the answers (mineral names) are Quantitative programmes can be divided into those which entered as a separate array at line 9f~. This programme stores process collected data so that results can be analysed, and the questions and answers in two DIM statements (lines 20 those which aim to re-inforce the learning process (computer-and 30) and once entered they can be stored on tape. To avoid assisted learning).

50

Fig. 2 Flow diagram for mineral identification

quartz

S T A ]J::$ R T

y

1 felspar

Fig 3

10 REM CSE MINERAL IDENTIFICATION 20 DIM AS (12,32) 30 DIM BS (10,32) 40 FOR X = 1 TO 12 50 INPUT AS (X) 65 PRINT AS (X) 70 NEXT X 80 FOR Y = 1 TO 10 90 INPUT BS (Y)

105 PRINT BS (V) 110 NEXTY 120 CLS 130 PRINT "CHOOSE A SPECIMEN" 140 PRINT 150 PRINT "DOES IT HAVE THE FOLLOWING" 160 PRINT "PROPERTY? (IF SO, PRESS Y)" 170 PRINT 180 FORZ=1T012 190 PRINT AS (Z) 200 INPUT CS 210 IF CS = "Y" THEN GOSUB 250 220 IF CS = "Y" THEN GOTO 120 230 IF Z = 12 THEN GOTO 120 240 NEXT Z 250 PRINT 260 PRINT "IT IS"; BS (Z) 270 FOR F = 1 TO 200 280 NEXT F 290 RETURN

A QUANTITATIVE PROGRAMME FOR A LEVEL: PROCESSING DATA ON PEBBLESHAPE FROM A BEACH An example of the former application is shown in figure 4 which is the listing for a programme designed to remove the arithmetical chore from pebble shape analysis using Zingg's classification of pebble form and Krumbein's sphericity index. The programme was initially written as a response to a discussion among' A' level geology and geography students on the potential value of having spent a morning taking measure­ments of pebbles along the coast near Aberystwyth. The geography students had taken the measurements with the main aim of studying the effects of longshore drift on pebble size distribution, but the geology students decided that the same data might also be used to test two hypotheses. The first is

51

mica gypsum

+ y

y

B Fig 4 ==============

10 PRINT "SAMPLE SIZE?" 20 INPUT X 30 LET S = 0 40 LET T = 0 50 LET U = 0 60 LET V = 0 70 LET W = 0 80 FOR J = 1 TO X 90 CLS

100 PRINT "PEBBLE ";J 110 PRINT 120 PRINT "A AXIS?" 130 INPUT A 140 PRINT "B AXIS?" 150 INPUT B 160 PRINT "c AXIS?" 170 INPUT C 180 LET F = 10 **(LN(B * C/{A * A))/LN 1013) 190 IF B/A > 0.67 AND C/B > 0.67 THEN GOTO 230 200 IF B/A> 0.67 AND C/B< 0.67 THEN GOTO 260 210 IF B/A < 0.67 AND CIB > 0.67 THEN GOTO 290 220 IF B/A < 0.67 AND C/B < 0.67 THEN GOTO 320 230 PRINT "SPHERE" 240 LET S = S+l 250 GOTO 340 260 PRINT "DISC" 270 LET T = T+1 280 GOTO 340 290 PRINT "ROD" 300 LET U = U+1 310 GOTO 340 320 PRINT "BLADE" 330 LET V = V+1 340 PRINT "S.1. = ";F 350 LET W = W+F 360 INPUT AS 370 IF AS ="" THEN GOTO 380 380 NEXT J 390 CLS 400 PRINT "SPHERES = ";S;" (";S *100/X;" PERCENT)" 410 PRINT "DISCS = ";T;" (";T *100/X;" PERCENT)" 420 PRINT "RODS = ";U;" (";U *100/X;" PERCENT)" 430 PRINT "BLADES = ";V;" (";V *100/X;" PERCENT)" 440 PRINT 450 PRINT "MEAN S.1. = ";W/X 460 STOP

that the alternation of shales and greywackes in the cliffs near Aberystwyth will give two 'populations' of pebble form, and the second is that pebbles with a high sphericity index, being less mobile than those with flattened shapes, will decrease in proportion higher up the beach. It was possible to test the latter hypothesis as the pebbles had been classed as being located at the beach summit, at the water edge or at a point mid-way between.

A QUANTITATIVE PROGRAMME FOR A LEVEL: PROCESSING DATA ON PEBBLESHAPE FROM A BEACH An example of the former application is shown in figure 4 which is the listing for a programme designed to remove the arithmetical chore from pebble shape analysis using Zingg's classification of pebble form and Krumbein's sphericity index. The programme was initially written as a response to a discussion among 'A' level geology and geography students on the potential value of having spent a morning taking measure­ments of pebbles along the cost near Aberystwyth. The geography students had taken the measurements with the mair aim of studying the effects of longshore drift on pebble size distribution, but the geology students decided that the same data might also be used to test two hypotheses. The first is that the alternation of shales and greywackes in the cliffs near Aberystwyth will give two 'populations' of pebble form, and the second is that pebbles with a high sphericity index, being less mobile than those with flattened shapes, will decrease in proportion higher up the beach. It was possible to test the latter hypothesis as the pebbles had been classed as being located at the beach summit, at the water edge or at a point mid-way between.

For each pebble in the sample the length of the a, band c axes are entered as inputs (lines 120 to 170). The form is deter­mined by calculating the ratios of the a and b axes and b and c axes (lines 190 to 220) thereby defining four categories (spheres, discs, rods and blades) and the sphericity index is calculated using the formula

(line 180)

Thus, for each pebble a name and number appear on the monitor (lines 230 to 340) to be noted by the pupils. The four terms used to describe pebble form were made more readily understandable by reference to a chart of visual ident­ification, as shown in figure 5.

A necessary sequel to all such data processing is that pupils are required to consider statistical questions and concepts such as adequacy of the sample size, deviations from normal distribu­tion and the choice of appropriate class intervals when drawing histograms. Using the processed data from 180 pebbles taken from three locations near Aberystwyth, the histogram shown in figure 6 was drawn. Sphericity is given as a decimal value between 0 and 1 .0 and a class interval of 0.02 was considered large enough to avoid too many empty classes, yet small enough to display sufficient detail. Given that the size of the sample was initially determined with a different purpose in mind from that for which it is being used here, the histogram nevertheless lends support to the pupil's initial speculations that the two rock types have given rise to two populations of pebbles, one more spherical than the other. The more spherical pebbles reflect the uniform resistance to attrition of the greywacke while the less spherical forms show the influence of fissility in the shaping of shale pebbles.

The hypothesis that spherical shapes will predominate lower down the beach and flattened shapes higher up was tested by

52

b

a

Fig. 6

No. of pebbles

14

F

c

• spheres

~discs

o rods

o blades

., ·2 ·3

Fig. 5

Visual identification 01 pebble form

Sphere

Disc

Rod

Blade o

Results of pebble shape analysis using pebbles from Aberystwyth

Sphericity Index

Location 1

1·0

0·9

0'8 • 0

0'7 ~ ~ >< ~ Q)

"tI 0'6 0--C l- D ~ 0 'u • .;:: 0·5 ...

~ Q) 0 .z: C- O 0 ... en ~ 0'4 ....

... ... ... 0·3

0·2

0·1

0

0 spheres

• discs

0 rods

... blades

Location 2

o o o ~ •

~ .. .... ... 0

o

0 AAA. ... 0 ...

...

... ...

...

A Beach summit

B Mid point

C Water edge

Location 3

0

0

• • ,t

• 0 .... • • ... • ;tl 0 0'"

0 oAA r/". ... • ... ... 0 ... ...

... ...

...

Fig. 7 Distribution of pebble forms at three beach locations near Aberystwyth

plotting the results for the three separate locations on scatter­grams (see figure 7). Locations 1 (SN 577797) and 2 (SN 578805) are located on a shingle spit at the mouth of the Aton Ystwyth, where longshore drift is from south to north. Location 1 is at the southern end of the spit and location 2 is near the northern end. Location 3 (SN 583818) is located at the southern end of Aberystwyth Bay, north of the spit, and separated from it by a rocky headland. At each location 60 pebbles had been sampled, 20 from each of the three levels on the beach. The results shown on the scattergrams are not conclusive, but this in itself was a stimulus for discussion, raising questions concerning not only the processes of pebble movement and sorting, but also adequacy of the sample size, randomness of the sampling procedure, and the effect of geographical position in relation to physical and human features.

A QUANTITATIVE EXERCISE FOR CSE PUPILS USING PEBBLE SHAPE DATA FROM A LOCAL GRAVEL QUARRY The same programme was used with CSE pupils working on a sample of 80 pebbles from a local pebble bed quarry in the Cannock Chase Formation (formerly in part the Bunter Pebble Beds) in the Satnall Hills (SJ 983208). The purpose of

53

using the programme in this case was not to test a formulated hypothesis, but to stimulate the pupils to consider the factors which influence pebble form. A more precise description of their form than the field observation that they are "well­rounded" was therefore needed and could be provided by the computer. The analysis of the shape of the pebbles using the measurements and the computer programme previously descri bed was:

Spheres Discs Blades

15% 54% 17%

Rods 14%

Mean sphericity index: 0.66

The meaning of the four terms used to describe form was again made clear by reference to the identification chart shown in figure 5. Fieldwork had already established that the pebbles have a probable fluvial origin and subsequent analysis showed that 76 of the pebbles (95%) were made of tough, homogeneous quartzite, two of vein quartz and two of weathered igneous rock. The relatively high sphericity index of 0.66 is accounted for by the homogeneity of the quartzite, though the pupils were able to point out that the prepon­derance of discs might well be due to a structural characteristic such as bedding or cleavage. Further, by asking them to consider how different shapes might be moved as part of the

bedload of a river, the pupils concluded that just as the rolling 'movement of spheres would tend to maintain their sphericity, so the sliding motion of discs would ensure that, once estab­lished, the shape would be retained.

THE COMPUTER AS A TEACHING AND LEARNING AID - THE CONCEPT OF HALF-LIFE A quantitative programme with a different application is shown in figure 8. Here the computer is being used as a teaching and learning aid, and as the programme is not designed to process collected data it requires only one input. Its aim is to put across the difficult concept of half-life as a statistical feature of the random decay of a large sample. The necessity for any simulation of radioactive decay to have a large starting quantity and an element of randomness makes the computer the only realistic option for illustration of the concept in the classroom.

10 20 30 40 50 60 70 80 90

100 110 120 130 140

PRINT "HOW MANY DICE?" PRINT INPUT X LET C = 0 FOR A = 1 TO 30 PRINT "THROW NUMBER ";A LET K = 0 FOR J = 1 TO X-C LET B = INT(RND*6)+1 IF B = 6 THEN LET K = K+1 NEXT J LET C = C+K PRINT PRINT "AFTER THROW NUMBER ";A:" THERE

150 PRINT K;" SIXES, LEAVING ";X-C;" DICE" 160 PRINT 170 PRINT "PRESS NEWLlNE FOR THROW" 180 PRINT "NUMBER ";A+1 190 INPUT X$ 200 IF X$="" THEN GOTO 210 210 CLS 220 NEXT A 230 STOP

Fig 8

The programme effectively 'throws' a chosen (input) number of dice (say 5,000) thirty times and after each of the thirty throws removes all the sixes, simulating the random decay of radioactive isotopes. Following each throw the number of dice left after removing the sixes is displayed on the monitor and can be plotted on a graph, as shown in figure 9. The results is an exponential curve from which the decay of the dice sample can be measured by reading the number of throws needed to reduce the sample by half. As long as the dice is six-sided, results should be similar for each run of the pro­gramme, but the half life can be altered to simulate, decay of different isotopes by increasing or decreasing the number of sides on the dice (the number in brackets in line 90 of the programme). The facility of choosing how many sides the dice shall have (also the number of throws) could easily be written into the programme.

CONCLUSIONS The growing importance of computers both in and out of school clearly makes it desirable that as many pupils as

54

•

Fig. 9 Plot of results obtained from the random decay of a 5,000 dice sample

Dice (minus sixes)

5000

4000

3000

2000

1000

10

... ........ 15

Throws

20 25 30

possible should have some computer experience, and the foregoing exercises show that geology is one area of the curriculum which offers good opportunities for the use of simple computers and BASIC language in the classroom. The rapid processing of raw data, the stimulation of geological though through the analysis of results, and the direct teaching, through simulation, of a geological concept, are three appli­cations which are of benefit to both the teacher and student of geology.

REFERENCES Briggs, D. 1977 Sediments. London, Butterworth 192 pp.

ACKNOWLEDGEMENT Mrs. P. Sephton, Head of Geography, Fair Oak School, whose 'A' level pupils collected the Aberystwyth pebble measure­ments.

Paul N. Green, Head of Geology, Fair Oak School, Rugeley, Staffordshire

I"

An exercise suitable for students at Advanced Level

vertical scale xl0

horizontal scale o 2km

DIPS ARE AS SHOWN: A

The Thatcher Tunnelling Co. are digging atomic weapons stor­age tunnels under Ben Wedgie in Northern Scotland. The Kremlin's top female agent, Kay Jeeby, has obtained - by very devious and dubious means - a partially completed geo­logical cross-section through the mountain and the tunnel.

Reconstruct the geology as best as you can, and then write an intelligence report for the Central Praesidium stating where you think side tunnels are likely to be, and where saboteurs could place explosive devices so as to cause maximum blockage in the tunnel.

Robin Stevenson and Andrew England, Geology Department, Norfolk College of Arts and Technology, Tennyson Avenue, Kings Lynn, PE30 2QW.

I>-~~ ~~((. . "-

6,,0 _,,("l.~~

MicA sCHisT OVER CONGLOMERATE

o~ ... fl.'. ~sc; o."r ~((.,,\ ..;\~'f.' A" o-..l ~s~ ~"\ ...

• J..\S~ ((.,,\ Il"v SCF o..,J~ rc,'~ • ..<.

CONGLOMERATE OVER SPOTTED SLATE. BUT SEPARATED BY MYLONiTE

GRANiTE'

liNE OF TUNNE~ SCALE: EXAGGERATED

MYLONITE SEPARA TES CONTORTED SPOTTED SLATE FROM FRACTURED WHITE QUARTZITE

",c~ _,~ < .. -> ,1-'" ,#~r O~" .o..~ 6,,0 ~,~ ~~ o.V' ~~

~ ",,\ cP~ ~,,~ ~Y-\ ;"'f\+-(J o-..l~((. r \~~

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PINK QUARTZiTE OVER

CONGLOMERATE

Il'l Il'l

ENERGY RESOURCES­FREE PUBLICATIONS

ENERGY IN GENERAL ENERGY, A MONTLY STATISTICAL BULLETIN OF ENERGY PRODUCTION AND CONSUMPTION. Available from: Central Office of Information, Circulation Section M, Hercules Road, London.

ENERGY - A KEY RESOURCE [CLASS COPIES]. Available from: Information Division, Department of Energy, Thames _ House South, Millbank, London SW1 P 4QJ.

OIL OIL FROM THE CONTINENTAL SHELF; FACT SHEET NO 2. [CLASS COPIES]; OIL THE WONDER FLUID [CLASS COPIES]. Available from: Information Division, Department of Energy, Shell Education Service, Shell Centre, London SE17NA.

GAS GAS FROM THE UK CONTINENTAL SHELF [CLASS COPIES] ; FACT SHEET NO 3. Available from: Department of Energy, Thames House South, Millbank, London SW1 P 4QJ.

BRITISH GAS AND ENERGY CONSERVATION [ONE COpy]; THE GAS REVOLUTION [CLASS COPIES]; BRITISH GAS FACTS & FIGURES [5 COPIES]; NATURAL GAS PROFILE [CLASS COPIES]; THE STORY OF OUR GAS [CLASS COPIES]; GAS MAP OF BRITAIN [ONE COpy]; GAS IN OUR TOWN WALL CHART [ONE COpy]; DISCOVERING GAS [CLASS COPIES]. Available from: The Education Liaison Officer, Room 414, British Gas, 326, High Holborn, London WCl V7PT.

ELECTRICITY UNDERSTANDING YOUR WORLD OF ELECTRICITY [CLASS COPIES]; POWER TO YOU [CLASS COPIES]; ELECTRICITY DISTRIBUTION [WALL CHART]; ELECTRICITY [WALL CHART] ; ELECTRICITY [MAP OF BRITAIN]. Available from: Understanding Electricity, Electricity Council, 30, Millbank, London SW1P 4RD.

SET OF WALLCHARTS: HOW ELECTRICITY IS MADE; NUCLEAR FUEL TO STEAM; FROM COAL TO STEAM; STEAM TO POWER; ELECTRICITY TO THE GRID. Available from: Central Electricity Generating Board, Sudbury House, 15 Newgate Street, London EC1AU 7AU.

NUCLEAR ENERGY NUCLEAR KNOW HOW [CLASS COPIES]; NUCLEAR POWER A REPORT ON PROGRESS; NUCLEAR POWER AND SAFETY. Available from: C.E.G.B., Sudbury House, 15, Newgate Street, London EC1AU 7AU.

56

NUCLEAR ENERGY IN THE UK - ORGANISATION; FACT SHEET NO. 5 [CLASS COPIES]; NUCLEAR ENERGY IN THE UK - POWER FROM THE NUCLEUS [CLASS COPIES] . Available from: Information Division, Department of Energy, Thames House South, Millbank, London SW1 P 4QJ.

ENERGY AND THE NEED FOR NUCLEAR POWER; HOW SAFE IS NUCLEAR POWER; NUCLEAR FUSION - POWER FOR THE NEXT CENTURY; NUCLEAR POWER - THE REAL FACTS; NUCLEAR POWER IN THE UK [WALL CHART]. Available from: United Kingdom Atomic Energy Authority, I nformation Services, 11, Charles II Street, London SW1Y 4QP.

ENERGY FROM THE ATOM (I) NUCLEAR POWER; ENERGY FROM THE ATOM (11) NUCLEAR FUEL; THE CASE FOR NUCLEAR POWER; WHO NEEDS NUCLEAR POWER. Available from: British Nuclear Fuels Ltd., Risley, Warrington, Cheshire.

COAL COAL IN THE UK; FACT SHEET NO. 4 [CLASS COPIES]; COAL INDUSTRY EXAMINATION FINAL REPORT; COAL FOR THE FUTURE 1977. Available from: Information Division, Department of Energy, Thames House South, Millbank, London SW1P 4QJ.

FACTS AND FIGURES. BRITAIN'S COAL INDUSTRY; YOUR PROJECT IS COAL [9 FOR 50p]. Available from: National Coal Board, Hobart House, Grosvenor Place, London SW1X 7AE.

NATURAL ENERGY THE POTENTIAL OF NATURAL ENERGY SOURCES. Available from C.E.G.B., Sudbury House, 15, Newgate Street, London EC1AU 7AU.

SOURCES OF VISUAL AIDS SHELL FILM LIBRARY; 25, The Burroughs, Hendon, London, NW4 4AT BP FILM LIBRARY: 15, Beaconsfield Road, London NW10 2LE N.C.B. FILM LIBRARY: Hobart House, Grosvenor Place, London SW1X 7AE BRITISH GAS FILM LIBRARY: Park Hall Road, Dulwich, London SE21 BEE. VISCOM A.V. LIBRARY: Park Hall Road, Dulwich, London SE21 BEL.

Simon G. Gosden, Fairfax High School, Fairfax Drive, Westcliff on Sea, Essex SSO 9RG.

ATG: BOOKS RECEIVED

In notifying the existences of the following books and materials the ATG does not wish to imply that it regards these books as appropriate to school, college or university geology or recommended for purchase. Where possible some details are given on the source of the books or material, their price and their likely market according to the following scheme: S = secondary (SL = Lower: SU = Upper); C = College of Edu­cation, Polytechnic and University students; F = Polytechnic, University and research; T = teachers' reference; G = general adult reference.

WI LSON, GI LBERT (in collaboration with COSGROVE, J.w.) 1982. Introduction to small-scale Geological Structures, London, Alien & Unwin. 128 pp. Handbook £10. Paperback £4.95. (C, F, T)

This book is, without apology, based on a classic paper of Gilbert Wilson published in 1961, and as such is a valuable, almost historical, summary of the subject up to that time twenty years ago. But the updating has added only a handful of more modern general references that are not so much discussed as fleetingly referred to. The net result is to produce a text that has left many of the vogue structures of the 1960s and 70s (e.g. shear zones, interference fold patterns and extension fibres) with a very superficial coverage.

But the book does cover aspects of field structural geology that have taken a back seat as global considerations have accounted for more and more of the precious teaching time. Because of its reasonable price, it will find space on the bookshelf of the better undergraduates or the geological historians, but it is more fitted to appear on additional, rather than essential, reading lists for undergraduate courses in polytechnics and universities.

R.C.S.

GEOLOGISTS' FIELD NOTEBOOK Geo-Supplies, 16D Station Road, Chapletown, Sheffield, S30 4XH (minimum order 10 books).

The stiff board cover and water-resistant pages certainly enabled me to reach home with field sketches in better con­dition than I'd managed before, and I've never had to dry it out on the nearest radiator. The 8" by 4" overall size when closed fits conveniently into map or anorak pockets, and into the inside pocket of most jackets, but the hinge along the short side makes it flap over awkwardly in the field. Two hands are really needed to hold it comfortably when open, though the book is strongly made and does fold back onto itself without apparently damaging the spine.

At £1.44 and £1.84 (including VAT) for the 40 page and 80 page versions respectively it is too expensive for student use, though it may well be valued by individual adults, or the professional fieldworker, whose field notes are referred to constantly and where therefore have a long file life.

Frank Dawson, Castle Head Field Centre, Grange-over-Sands, Cumbria, LAA11 SOT.

57

LINES PENNED TO ENLIVEN A FOSSIL PRACTICAL

The corals of the Carboniferous Grew in great profusion, But dating time within the Carbo Has caused some great confusion.

Because the seas weren't shallow all, The corals didn't grow In basins deep (Northumberland), And Scotland's deltas - NO!

And corals are so fussy that, They need a clear warm sea, With depths where light can penetrate, And 22 deg. C.

They are the real conservative; Their shape shows little change: It's not surprising with all this, They have a large time range.

Benthonically fixed they grew, Their stringent needs we know; But though they fail in dating rocks, It's not a fatal blow.

For where they grew we can be sure What seas and depths were there, And fossil reefs can plotted be At Wenlock and elsewhere.

Environmental fossils thus, They can be called with glee; Because with hardly any fuss The past we thus can see!

D.H. Fielding

O. 1. What age are the fossil reefs at Wenlock?

O. 2. List the reasons why coral is a poor zonal fossil.

D.H. Fielding, Head of Geology Department, Radley College, Abingdon, Oxfordshire.

ODE TO MICRASTER SP.

Embedded in the Upper Chalk, Micraster can be found. Beware the man who steps this way, For this is tricky ground.

A zonal fossil proud is Mike, Whose evolutionary change, By subtle changes in his shape, Allows a short time range.

Because with time his sulcus depth Became more marked to see: Thus valentined the dorsal view; Romantic could he be? For other changes you will need To study Kirkaldy.

Can YOU state another change in Micraster without reference to Kirkaldy? Add it below:

Kirkaldy, J.F., 1975. Fossils in Colour, London, Batsford.

Idij i iV ---------"-----------------_ .........

FIELDWORK WORKING GROUP REPORT 1980-81

During the second year of this group's existence it has not been possible to circularise and correspond with its enlarged membership, currently 21. An ATG Policy Statement prepared by the group was published in 'Geology Teaching' 5(4), p. 146. At the Group meeting held last September, four members agreed to help with drafting a document on "Field Techniques Compatible with Site Conservation". This has now been done and we hope to publish it eventually in Geology Teaching. The Group has been in liason with the NCC through Laurie Richards, whose paper discussing the problems on site conser­vation has been published (Geology Teaching, 6(2)' pp. 66-9.)

Our other main activity has been to investigate the educational value of specific fieldwork sites. As a pilot scheme, about 60 questionnaires were sent out to record centres of the National Scheme for Geological Site Documentation, to ATG Local Groups, and to members of the Fieldwork Group. Each questionnaire asked respondents for details of two sites particularly suitable for teaching. There were 27 replies and details of 47 sites have been received. Some record centres indicated the extent of their records and some mentioned that as yet, teachers were making little use of the scheme. In ' Warwickshire there are over 100 sites recorded as suitable for educational purposes, in Kent over 200, in the Sheffield area 500-600 sites, in North Yorkshire 2000 sites, and in the Forest of Dean 66 sites.

It is debatable whether the Fieldwork Group should become involved in documenting sites of educational value. Some members have criticised this activity, considering it a dupli­cation of the more comprehensive documentation currently being carried out by the Nature Conservancy Council, the museums and other bodies. Many members believe that encouraging geology teachers to use the increasing quantity of data on alternative or new field sites is perhaps a more worth­while approach.

Or D.J. Gobbett, Department of Geology, Sixth Form College, Widney Manor Road, Solihull, West Midlands

58

Forest of Dean LlTTLEDEAN ---

"The Guest House in Littledean is becoming quite a rendevous for many British geologists as the village is an excellent centre for Dean" extract from GEOLOGY EXPLAINED IN THE FOREST OF DEAN AND WYE by William Dreghorn.

We specialise in providing accommodation for Geology, Geography and Civil Engineering field parties.

Good food and accommodation, total capacity 100. Large car park and garden. Lecture room seating 50. Lounges, pool room, drying facilities. Fully licenced.

Dinner, bed and breakfast and packed lunches. Schools from £6.30 daily. Colleges from £10.30 daily inc. VAT. Special rates October to February.

LlTTLEDEAN HOUSE HOTEL, LlTTLEDEAN, CINDER FORD, GLOUCESTERSHIRE, GL14 3JT

~ 059422106

* WHITBY * The proprietors of ESKLET GUEST HOUSE wish to offer accommodation to Geology students at reduced party terms. "

ESKLET is a comfortable Georgian House with accommodation for approximately 18 guests.

For further information please apply to:

Miss P Hudson Esklet Guest House 22 Crescent Avenue West Cliff WHITBY N. Yorkshire Y021 3ED

Telephone: (0947) 605663

On discerning the purposes of Geological Fieldwork

The editor outlines his views of the context in which the Fieldwork Working Group of ATG should seek to develop a rationale for writing the forthcoming booklet on the organ­isation and methods of teaching geological fieldwork_

INTRODUCTION The stating of purposes in education (aims, goals, objectives) is as fashionable as it is fundamental. The Schools Council Geology Curriculum Working Group (1977 P. 25) quoted Mager (1962) in its effort to draw attention to the need to consider such basic issues: "If you're not sure where you're going, you're liable to end up some place else".

The present note arises from a wish to further the efforts made by the ATG Working Group (Stevenson and England, 1981) to tackle the problem of offering members sound advice on the organisation, methodology and philosophy of fieldwork.

Fieldword is here taken to be the out-of-doors, practical, experimental study of the processes and features of the physical, chemical, biological and man-made world in natural surroundings. It is a moot point whether some kinds of 'street­work' should be included in this definition.

GEOLOGICAL FIELDWORK IN RELATION TO GENERAL EDUCATION Whatever fieldwork experiences are planned, they should be designed to contribute as fully as possible to the aims of education in general. A major Schools Council Report (1981) gives a consensus statement of the aims of education (see Warnock and others 1978):

"first, to enlarge a child's knowledge, experience and imaginative understanding, and thus his awareness of moral values and capacity for enjoyment; and secondly, to enable him to enter the world after formal education is over as an active participant in society and a re­sponsible contributor to it, capable of achieving as much independence as possible_"

The Schools Council document "The Practical Curriculum" (1981) enlarges upon the capacity and the will of schools and colleges to help students to these ends. Schools and colleges should aid students:

• • •

to acquire knowledge, skills and practical abilities, and the will to use them; to develop qualities of mind, body, spirit, feeling and imagination; to appreciate human achievements in art, music, science, technology and literature;

•

• •

to acquire understanding of the social, economic and political order, and a reasoned set of attitudes, values and beliefs; to prepare for adult lives at home, at work, at leisure, as consumers and citizens; to develop a sense of self-respect; the capacity to live as independent, self-motivating adults, and the ability to function as contributory members of cooperative groups_

The Association for Science Education and the National· Foundation for Educational Research Colleges Curriculum Project through Squires (1976, pp. 2-11), remind us of the basic physiological, psychological and social needs of the individual student (physical, intellectual, maternal, paternal, fraternal) and the paramount requirement to cater for these needs by providing appropriate experiences: through member­ship of groups at work and in leisure; through developing independence and a satisfactory self-concept; through en­hancing the skills of communication between individuals and groups. The ultimate need is to develop a soundly-argued philosophy of life.

The general aims of environmental education by the age of 16 have been set down by DES (1979) see Sinker 1979 p. 7) and are wholly concordant with the above:

1.

2_

3.

4.

5.

6.

7.

8.

"It seems important that those who will shortly become autonomous citizens should, to the extent of their capabilities:

view their surroundings with an eye both appreciative and critical; be competent in a range of environmentally related skills; understand something of the processes of the physical world and especially have a basic knowledge of eco­logical principles and relationships; understand something of the economic, technological, planning and political processes which affect man's use of his environment; have a degree of insight into other people's environ­ments, life styles and predicaments; understand something of the interdependence of people and the nature of the resource-base upon which mankind relies; show developing attitudes of concern towards their environment and the environments of others; in so far as environmental issues are concerned have a basis on which to develop the ability to make informed decisions affecting themselves and society and the interest to do so_" ,

As will be apparent later, certain kinds of fieldwork, properl'! planned and prosecuted, can contribute to a remarkable degree to the achievement of these general aims of education.

THE PHILOSOPHY OF FIELDWORK If we turn to the rationale of fieldwork in education as seen by its practitioners, we find that there is relatively little written. Sinker (1973, p. 657; 1979, p.6) suggested that the aims of fieldwork were often "faith dressed up as reason"; much dependent on the values of those judging the proposals. He believed that many students and teachers favoured fieldwork from subjective, largely subconscious, motives.

The Study Group on Education and Field Biology (1963, pp. 10-15) noted boys' and girls' innate interest, curiosity and patience in studying animals, plants, earth, air and water when they first go to school. They draw attention to the great

59 variety of activities and skills associated with the proper study

of things outdoors. They highlighted the problems of young people growing up in urban surroundings without access to and facilities for spontaneous recreation and outlets for "aggressive and exploring instincts." They heralded the need to cater for the increase of mobility and leisure time amongst adults. They found that it was not possible to assess the value to the community of universal and well-run field studies in terms of prevention of delinquency and damage to property, but they quoted the favourable evidence of the Albermarle Report (1960). They noted that the heavy burdens of modern life were mitigated by the perennial refreshment provided by outdoor pursuits and nature study. They remarked on the early ventures into space: "The more man thinks in terms of outer space the more important it is to understand the earth and life sciences, and to develop an intelligent perspective ... as a result of a very much more integrated and critical view of the conditions of our own planet.

The group proposed five criteria by which high quality in fieldwork could be recognised. These related to courses which encouraged:

1. A spirit of enquiry relating to original observations and the exploration of unknown material;

2. A means to an end, wherein students could recognise that the methodology of their fieldwork was related to a defined problem and its solution;

3. Students' initiatives in planning their own projects either individually or in teams, so that they wished spon­taneously to return to a site or tackle related problems in another area;

4. Accurate recording, using a variety of approaches and techniques;

5. Experimental confirmation (sic) of hypotheses.

Sinker in Herbert et al (1972), p. 657) recognised that field studies served five interrelated functions; to promote:

1. "Experience of the material world . .. an infinitely richer source of first-hand data than the classroom or the laboratory; excursions ... wider horizons beyond the home and school ... the bricks and mortar from which the edifice of learning is built";

2. "Logical thought, through the use of reasoning processes ( ... unconscious and formal) fed by first hand data easily cheaply and selectively ... by the student himself ... he develops the capacity to manipulate facts in increasingly sophisticated ways, the engineering tech­nology by which the edifice ... is built"

3. "Enthusiasm for learning, spontaneously generated in unfamiliar and stimulating surroundings by releasing ... natural curiosity ... and harnessing it purposefully, rather than pushing the unwilling mind up a gradient of boredom ... "firelighting" rather than "potfilling". This, in part, is the aesthetic and emotional vehicle, the architectural style of the edifice ... "

4. Citizenship training (through 1-3) leading to " ... better understanding of our environment, its ... parts and ... problems ... a critical awareness of ... conservation and a basis for responsible political jUdgement."

5. "Technical training of the important minority who will be in the land-linked professions, agriculture, extractive and constructional industries ... future officers of local government. .. teachers and field scientists in the making"

Sinker notes that while these functions taken singly are shared with other modes of education, he claimed that their collective role is unique to field studies. Here attention is drawn to how

60

well these functions relate to the general purposes of edu­cation cited earlier.

Sinker (1979, p. 7) adds that whereas the frontiers of science are remote from students and teachers in many parts of the sciences, in the field sciences they still overlap our own scale of magnitude; "the unknown is surprisingly close and access­ible at many points and can often be explored with the un­aided human senses". The size, scale, richness, diversity and complexity of things, the rates at which natural processes work, have to be felt to be believed and understood. Further­more he suggests that a week of intensive fieldwork creates more interest in, and understanding of a subject than a term in the classroom, a view widely shared by ATG members.

This last theme has been taken up by a host of geologists who have written less philosophically about these matters. Quota­tions may suffice to give an indication of the high regard in which fieldwork has been held:

British Association for Advancement of Science (1937, p. 283) "Geology taught without proper regard to the phenomena which the pupil can observe and study for himself must become dull and unreal."

J. Platt (1946, p.20) "Any attempt to neglect the practical and out-door aspects and to teach the subject in any other way will be doomed to failure ... Moreover, it will follow that his scholars, being likewise obliged to depend upon the obser­vations of others, will soon become quite content to do so, and thus the teaching will fail in its object to train the powers of observation, the whole value of its training in scientific method will be lost and the chief objects of its inclusion in the curriculum will be frustrated."

(p. 18) "The subject supplies ample scope for true scientific training, training in observation, in the investigation of observed facts, in the testing and applying of inferences, and in their interpretation and classification."

v. Wilson (1947, p. 4) "Secondly, I cannot plead too strongly that any programme of instruction in geology in schools must at all times stress the pupil's experience in both the subject matter and method of science. Early everyday experiences if not rationalised into knowledge soon become evanescent as the child grows older. His restless observation should be encouraged and made as accurate and complete as possible, and only when his acquintance with geological phenomena is becoming tolerably exhaustive should he be introduced to the new sources of information which our textbooks supply. In teaching geology we must not put theories, definitions, rules and principles first, but disclose them as they come in the order of nature through the study of examples."

Greensmith (1965, p. 482: re C.S.E.) "The basis of the syllabus, and its attendant examination, is as far as possible the immediate school area. The pupils should be encouraged to inspect the local rocks and scenery as much as possible despite timetable disorganisation."

George et al. (1967, p. 65: re Secondary Modern schools) " ... geology only comes to life when the pupil himself be­comes a geologist ... Geology then is an intrinsic part of field study and the end of the teaching exercise is to give the pupil some understanding of the geological processes and products he himself has seen. Excursions, therefore, should form an accepted, central part of the teaching of geology, and should indeed be the peg upon which geology hangs .... insufficient concern with processes may result in the pupil's

failing to understand the significance of the products as he sees them in the actual rocks and in the specimens he collects in his own neighbourhood."

Bradshaw et al. (1970, p. 77: re 0 level) "Geology should therefore provide the student with training and experience in observation, measurement and interpretation; ... The em­phasis placed on a scientific approach to geology is important . . . Fieldwork is the only way in which the full evidence avail­able can be appreciated, and should form an important component of the course."

Bassett (1971, p. 73) "it is much easier for a child to learn geology by behaving like a geologist than by doing something else. That something else usually involves what ... Bruner ... describes as "middle language" - classroom discussions and text books that talk about the conclusions in a field of inquiry rather than centering upon the inquiry itself".

GEOLOGICAL FIELDWORK IN RELATION TO SCIENCE EDUCATION It might be argued that geological fieldwork should take account of the overall contexts within which scientific know­ledge can be deployed. The Association for Science Education (ASE 1979 p. 38-9) have suggested that these contexts can be classified thus:

1. Science as science; the pursuit of knowledge as an end in itself, as an intellectual activity, seeking to establish the essential foundations upon which higher education would build to equip an individual to undertake research and development;

2. Science as a cultural activity; the generalised pursuit of knowledge; of the history, philosophy, literature and sociology of science; the contribution of science 'to society and the world of ideas;

3. Science and citizenship; the understanding of scientific and technological matters so as to be able to participate in an informed way in the democratic process of decision-making, especially in areas relating to appli­cations of knowledge;

4. Science in the world of work; the study of the ways in which scientific and technological ideas are used to make an economic surplus, their use in industrial, commercial and social situations;

5. Science and leisure; understanding that science and technology provide the basis fora wide range of hobbies;

6. Science and survival; understanding that the role of science and technology relates to human survival, self-sufficiency, the careful use of resources, the develop­ment of alternative technologies.

The ASE further believes that education through science should enable the individual, by the end of the period of compulsory education, to have studied a kind of science which has embodied the following aims (ASE 1981, pp.11-12):

1. The understanding of basic scientific concepts, generali­sations, principles and laws;

2. The acquisition of a range of cognitive and psychomotor skills and processes as a result of direct involvement in scientific activities and procedures in the laboratory and the field;

3. The utilisation of knowledge and processes in the pursuit of deeper understanding and the ability to function autonomously in order to solve practical problems and to communicate that experience to others;

4. The attainment of a perspective or way of looking at the world;

61

5. The attainment of a basic understanding of advanced technological societies, the interaction of science and society and the contribution of science to our cultural heritage;

6. The realisation that scientific knowledge and experience is of value in the process of establishing a sense of personal and social identify.

Consideration of these contexts and aims might induce teachers to plan fieldwork which would have students "being a geologist for a day" (George et al 1967, Bassett 1971), serving an academic apprenticeship context 1; aim 1) and exercising a range of skills, abilities, techniques and attitudes which had been carefully defined beforehand (context 1; aim 2). Field­work areas might be chosen because they are currently at the frontiers of geological research ego areas like the Southern Uplands and the Lake District on either side of the hypo­thetical lapetus suture (context 1; aim 1). Care would be taken to relate fieldwork to the basic concepts, generalisations, principles and laws of science and to have students elucidate and utilise the many principles to do with the materials, processes and space-time thinking which are unique to geology (eg in igneous, metamorphic or stratigraphic studies) (context 1; aim 1). Field areas might be chosen so as to go over ground where seminal ideas were generated: the Huttonian uncon­formities and the granite margins of the south and north of Scotland respectively; the Moine Thrust Zone; the Barrovian zones of the Highland Border; the Somerset Canal Cuts; the lower palaeozoic Welsh Basin etc. (context 2; aim 5). Students would be encouraged to recognise and solve problems them­selves and communicate their findings orally and in writing to others (context 1; aim 3). Field areas would be carefully chosen so as to include the industrial applications of science: sites for the storage of gas or nuclear waste underground; for geothermal power; for dams; and for sand and gravel, coal, ironstone, copper and salt extraction. Study of such sites would very quickly highlight conflicts of exploitation and amenity and raise issues of conservation and preservation (contexts 3,4,5,6; aims 4, 5 6, 7). Students would be en­couraged to join local geological societies and staff would wish to set them an example (context 5; aims 5, 6). Finally, how­ever, there would be no doubt in the minds of those whose experience of taking students in the field is extensive, that aims 4 and 6, to do with gaining a perspective and a sense of personal and social identity, are uniquely fulfilled by well­planned field weeks and camps. Indeed the virtues of organising field weeks and camps compared with seven separate field days might be considered to be overwhelming.

THE PURPOSE OF PRACTICAL WORK IN SCIENCE EDUCATION Fieldwork is a form of practical work, and much has been written in general about the purposes of practical work in science education. Here attention is draw to only a few of the salient statements which have found a measure of agree­ment in the teaching community in the last 15 years.

For 11-12 year olds the following statements, in rank order of importance were considered to be the most salient by a large sample of science teachers in primary, middle and in­dependent schools (Assessment of Performance Unit 1981, p.37).

TABLE 1 The goals of science based activities for 11 year old pupils in rank order according to a large sample of teachers in Junior, Middle and Independent Schools.

1. A questioning attitude towards the surroundings 2. Ability to observe carefully 3. Enjoyment of science·based work 4. Knowledge of the natural and physical world 5. Ability to carry out simple experiments carefully and

safely 6. Recognition of patterns in observations of data 7. Problem solving skills 8. Ability to find information from reference books 9. Understanding of basic science concepts

10. Familiarity with correct use of simple science equipment 11. Appreciation of relevance of mathematics to real

problems 12. Ability to plan experiments

For older secondary school pupils, the purposes discerned were comparable but the rank order was somewhat different (Table 2; Kerr 1963, see also Eggleston and Newbould 1969).

TABLE 2 The purposes of practical work in science in years 3-5 (13-16) of secondary grammar, modern and comprehensive schools.

1. To encourage accurate observation and accurate recording 2. To promote simple commonsense scientific methods of

thought 3. To be an integral part of the process of finding facts by

investigation and arriving at principles 4. To elucidate theoretical work so as to aid comprehension 5. To arouse and maintain interest in the subject 6. To make scientific phenomena more real through actual

experience

~ SUBJECT ORDER 1 2 3 4 5= ORDER

BIOLOGY 1 4 2 3 (5,7)

7

9

CHEMISTRY 1 2 3 7 (4,6) 4=

PHYSICS 1 2 4 3 (5,9)

Members of ATG and the ATG Fieldwork Working Group are invited to write their own statements of purpose, first for practical work generally, then for fieldwork, before reading, this article any further. Separate lists will probably be needed for each age and ability group.

THE SEARCH FOR STATEMENTS OF THE PURPOSES OF FIELDWORK

6

If we search the literature for statements concerning the purposes of geological fieldwork, we find that we have to infer any aims and objectives from the context of discussions in which proposals are often exemplified but not explicitly stated in a clear way. The statements many be sought in textbooks

62

&&

7. To fit the requirement of practical examination regulations

8. To develop manipulative skils 9. To give training in problem solving

10. To verify facts and principles already taught

B

11

8

8

With respect to 16-19 year old Advanced level students, the following twenty statements of purpose (Table 3) were distilled from the replies of a very large sample of practising biology, chemistry, physics teachers (Thompson, J.J. 1975). The results have been placed in an overall rank order by the present author. The rank order favoured by the separate groups of subject specialists is cited below the table.

TABLE 3 The aims of practical work in science at Advanced Level

1. To encourage accurate observation and description 2. To make phenomena more real through experience 3. To promote a logical, reasoning method of thought 4. To develop a critical attitude 5. To become able to comprehend and carry out instructions 5. To arouse and maintain interest 7. To develop specific manipulative skills 8. To help remember facts and principles 9. To develop certain disciplined attitudes

10. To develop self-reliance 11. To practice seeing problems and seeking ways to solve

them 11. To elucidate theoretical work as an aid to comprehension 13. To give experience in standard techniques 14. To develop an ability to communicate 14. For finding facts and arriving at new principles 16; To prepare the student for practical examinations 17. To verify facts and principles already taught 17. To develop an ability to cooperate 19. To be a creative activity 20. To indicate the industrial aspects of science

9 10 11 = 13 14 = 16 17 = 19

8 9= (14=,6) 12 (14,16) 13 (18,19) 17

9 11 (12,13) 10 (14,15) 13 (1B,19) 17

11 10 (12,13) 13 (12,15) 15 (18,19) 17

20

20

20

20

and pamphlets (for example Alum 1966, Barnes 1981, Bates and Kirkaldy 1976, Compton 1962, Enson 1979, Geikie 1900, Geologists Association 1978, Greenly and Williams 1930, Kottlowski 1965, Lahee 1961, Lattmann and Ray 1965, Moseley 1981, Simpson 1977); or in articles (for example Greensmith 1958, Crossley and Mordue 1972, Harpum 1973, Kennett 1979, Lusty 1973, Thompson 1974,1975, 1979); or in syllabuses and notes of guidance published by the boards (see an early summary in Thompson 1974, but also for example Associated Examining Board 1974, Joint Marticu­lation Board 1978, Welsh Joint Education Committee 1979, West Midlands Regional Examining Board 1979, Northern Ireland Examining Board 1980, North Western Regional Examinations Board 1975.)

Rather than attempt to summarise these accounts, the author commends their study to the Working Group, and here prefers to distil the wisdom provided by their varied approaches in order to present lists of possible objectives of geological fieldwork in the hope that they can be discussed and, with emphasis for different age groups, adapted to varying degrees, both by the membership and the Working Group.

A STATEMENT ON THE PURPOSES OF GEOLOGICAL FIELDWORK The general aims of geological fieldwork are:

1. To have fieldwork contribute to the fulfilment of as many as possible of the aims of general education and science education which have been set down recently in the course of the curriculcum debate (1976-present). (See earlier sections).

2. To have students gain an interest in recognising and solving field problems, so that they may be motivated to do so after they have left school or college, perhaps when they are at home or travelling on business or on holiday, as an amateur or a professional.

It is most important philosophically that the fieldwork experiences should include the monitoring of present day geological processes in both natural environment and the laboratory. Alas! experimental work in the field or the lab­oratory is not encouraged by any CSE 0 or A level syllabus known to the author, and this is a constant source of friction when the virtues of geology for an education through science are discussed with science educators from other disciplines. They merely point out that the geologists pay but lip-service to the uniformitarian doctrines which they trumpet so loudly: present day ecological, volcanic, glacial fluvial, aeolian, lacustrine, intertidal and marine processes and environments are rarely investigated experimentally by undergraduates, never mind school students. How can students study the ancient rock record retrodictively and critical!y if they have no experience of, or feel for, the processes of erosion, transport, sedimentation, crystallisation, deformation etc?

Specific aims and objectives of fieldwork may be classified with the help of educational taxonomies, and may best be stated in terms of what the students should be able to do at the end of their courses which they could not do at the beginning (Table 4).

TABLE 4 Possible purposes of geological fieldwork without regard to constraints relating to age, ability, resources, equipment, finance

1. To develop intellectual skills and abilities

(a) to display knowledge of the procedures, apparatus and techniques commonly used in the field;

(b) to display knowledge of the terminology, symbols and conventions appropriate to fieldwork;

(c) to recognise potentially worthwhile field problems; (d) to research appropriate literature prior to going in the

field (including air photographs); (e) to understand and follow instructions relating to

fieldwork; (f) to plan, organise and administrate one's own and

others' fieldwork; (g) to search for patterns in data; (h) to think inductively and hypothetico-deductively; to

make hypotheses and predictions 63

2.

3.

(i) to analyse data in the field and later in the labora-tory, in part alone, in part by discussion with others;

(j) to devise ways of testing hypotheses; (k) to rank hypotheses in order of priority; (I) to draw reasoned conclusions; (m) to write concise reports in which problems are

explained, and data synthesised and evaluated.

To develop practical skills and abilities

(a) to locate and recognise practical field problems; (b) to observe as accurately as possible in a methodical

and disciplined way; (c) to record observations as accurately and methodically

as possible at the outcrop; (d) to locate and reference localities in conventional

ways, in such a manner that an observer could locate the exact spot many years later;

(e) to collect and reference materials in conventional ways, the reference system used in the field to stand equally well in the laboratory;

(f) to conduct experiments in a natural setting (e.g. using streams crossing a beach to produce sedimentary structures) ;

(g) to follow up field work and field identification by making laboratory tests/identifications and by pro-cessing samples brought in from the field;

(h) to follow up fieldwork by devising and carrying out experiments in the laboratory;

(i) to think three-dimensionally and spatially; (j) to think four-dimensionally and in terms of constant

change in space and geological time; (k) to solve practical geological problems through the

development of skills (a) to (j) and techniques (I) to (0);

(I) to report observations, hypotheses, predictions and conclusions orally in a clear manner to colleagues.

To master practical techniques

(a) to manipulate and use relevant tools skilfully and safely (clinometer, compass, spirit level, tape, rule, dilute acid dropper bottle, penknife, coin, grain size comparator, etc, and on occasions, with permission, a chisel and hammer).

(b) to read, use and make geological maps. (c) to develop the habits and techniques associated with

measuring quantatively in SI units (dips, strikes, azimuths, bed thicknesses, sizes of grains, numbers and orientations of fossils, joints, cleavages, cross­beds, cross-bed thicknesses, shapes (roundness and sphericity) of pebbles, successions etc.)

(d) to practise a variety of techniques of recording using conventional symbols and scales: on loose paper, in a field notebook, by a graphic log, by camera.

4. To develop interests and attitudes

(a) to work methodically in a disciplined way; (b) to work independently; (c) to work as part of a team; (d) to lead a team; (e) to conserve geological data and the beauty of the

countryside and coastline by reducing, hammering and collecting, and by following codes produced by geologists, botanists, entomologists, the countryside commission, the national parks, the National Trust and others;

(f) to contribute to the health and safety of oneself and others by adoPting sound practices and using approved equipment;

(g) to be interested in researching problems of access to geological sites thoroughly in a way that befriends rather than alienates landowners and country people;

(h) to pursue scientific knowledge as an end in itself; (i) to pursue scientific knowledge as a springboard for

interesting oneself in its applications for the good of mankind and its relationship to other interrelated cultural activities;

(j) to be sceptical of consensus hypotheses and theories; to be keen to test them and substitute new hypo­theses;

(k) to empathise with the presentation of new ideas by others, and be willing to articulate ones' own.

CONCLUSIONS In order to develop a sound rationale for the writing of hand­books of advice, it is necessary to consider how the aims related to one area of work, in this case geological fieldwork can contribute to and complement those of a wider nature, for example the general purposes of education as expressed in the work of schools, colleges and universities, the needs of the students, the contexts in which scientific knowledge is de­ployed, the aims of science education and the purp~ses of practical work in science. Equal emphasis should be given to utilising the approaches, techniques, generalisation, principles, and theories of the basic sciences as well as those unique to the geological sciences. An important emphasis should be given to having pupils monitor present-day geological processes experimentally, so that the uniformitarian method is made explicit and is criticised. Traditional ways of organising and prosecuting fieldwork need to be scrutinised with a view to discerning what the student, at any age or ability level, ought to be able to accomplish at the end of the course which he or she could not do at the beginning. The lists of the possible purposes of fieldwork are provided in order to help raise the process of selection of suitable tasks and skills to a conscious level. In view of the many constraints which operate in individual schools, colleges and universities, the purposes to be achieved may vary widely from institution to institution, even for the same age and ability level.

ACKNOWLEDGEMENTS The editor wishes to thank lan Hunter for his kindness in criticising early drafts of the manuscript.

REFERENCES Albermarle, D.C. 1960 The youth service in Englan~ ~nd Wales; a report of the committee appointed by the Minister of Education in November 1958 (Chairman The Countess of Albermarle (Cmnd 929). London, HMSO for the Ministry of Education. Alum, J.A.E. 1966 Photogeology and regional mapping. Oxford, Pergamon. Assessment of Performance Unit 1981 Science in Schools Age 11 Report No. 1. London, HMSO for Department of Education and Science. Associated Examining Board 1974. Suggestions on the organisation of Fieldwork (Geology 0 and A level (1974). Aldershot, AEB 8 pp. Association for Science Education 1979 Alternatives for Science Education, Hatfield, ASE, 61 pp. Association for Science Education 1981 Education Through Science. Hatfield, ASE, 56 pp.

64

Barnes, J.W. 1981 Basic geological mapping. London, Open Univ. Press for Geol.Soc. Lond. 112 pp. Bassett, D.A. 1971 Geology in education today. (Presidential Address). Geology 3,65-80. Bates, H.E. & Kirkaldy, J.F. 1976 Field Geology in Colour. London, Blanford Press. 215 pp. British Association for Advancement of Science 1937 Teaching Geology in Schools. Brit.Ass.Advt.Sci.Rept., 281-90. Bradshaw, M.J. et al. 1970 The syllabus requirements of Ordinary Level geology courses. A report by a committee of the Association (of Teachers of Geology). Geology 2, 77-80. Compton, R.R. 1962 Manual of Field Geology. New York, Wiley. . Crossley, J.D. & Mordue, C.G. 1972 Geological Research In

. Schools. Geology 4,30-37. Department of Education and Science 1977 Curriculum 11-16. London, HMSO. Department of Education and Science 1979 Aspects of Secondary Education in England. London, HMSO. Eggleston, J.F. and Kerr, J.F. 1969 Studies in Assessment, London, English Universities Press. 226 pp. Eggleston, J.F. and Newbould, C.A. 1969 Assessing Attainment in Science at CSE level. pp. 15-76 in Eggleston, J.F. and Kerr, J.F. 1969 (see above). Ensom, P.C. 1979 The geological field notebook. Dorchester, Dorchester County Museum. 6 pp. Geikie, A. 1900 Outlines of field geology (5th edition) London, Macmillan 260 pp. Geologists Association 1978 Codes for Geological Fieldwork. London (leaflet). George, T.N. et. al. 1967 Geology in Primary and Secondary Modern Schools. Geological Society of London Education SUb-committee & British Association Committee on teaching geology in schools. Proc. Geol. Soc. Lond. 1638, 61-73. Greenly, E. and Williams, H. 1930 Methods in geological Surveying. London, Murby, 420 pp. Greensmith, J.T. 1958 The introduction of geology into the Secondary Modern School Curriculum. School Science Review 40,104-108. Greensmith, J.T. 1965 Geology and the CSE School Science Review 46, 481-483. Harpum, J. 1973 Geological Mapping: Part 1. Philosophy. Amateur Geologist 6, 15-28. Herbert, A.T., Oswald, P.H. & Sinker, C.A. 1972 Centres for Field Studies in England and Wales: the results of a question­naire survey in 1969. Fld. Studies 4, 655-79. Joint Matriculation Board 1978 Geology Advanced. Pilot Scheme investigation of the assessment of practical skills. Notes for guidance of teachers. Manchester, JMB 22 pp. Kennett, P. 1979 A field excursion of the Carboniferous Limestone for A level students. Geology Teaching 4 (4), 154-8. Kerr, J.F. 1963 Practical work in school science. An account of an enquiry sponsored by the Gulbenkian Foundation into the nature and purposes of practical work in school science teaching in England and Wales. Leicester, Leicester University Press. Lusty, M.G.F. 1973 The place of fieldwork in geology. Geology 5, 85-86. Mager, R.F. 1962 Preparing Objectives for Programmed Instruction. Fearon, San Francisco. Northern Ireland Examinations Board 1980 (Supplementary notes on the A level geology syllabus). North Western Secondary Schools Examination Board 1975 (Notes for guidance of teachers carrying out fieldwork at CSE level) Manchester, NWSSEB. Kottlows,ki, F .E. 1965 Measuring Stratigraphic sections. New York. London, McGraw Hill, 256 pp.

Lahee, F.H. 1961 Field Geology (6th Edition) New York, McGraw Hill. 926 pp. Lattman, L.H. and Ray, R.G. 1965 Aerial photographs in field geology. New York, Reinhart and Winston. Moseley, F. 1981 Methods in Field Geology, Oxford, Freeman & Co. 211 pp. Platt, J.I. 1946 The teaching of geology in schools - I. Geology a teaching subject. School Science Review 28.17-22. Schools Council Geology Curriculum Working Group (R.C.L. Wilson Editor) 1977 Geology in the School Curriculum (SC Working Paper 58). London, SC Evans/Methuen 96 pp. Schools Council 1981 The Practical Curriculum. Working Paper 70. London, Schools Council 71 pp. Simpson, I.M. 1977 Fieldwork in Geology. London, Alien and Unwin. 72 pp. Sinker, C.A. 1979 The aims of fieldwork. Review of environ­mental education developments (REED) 7 (2),6-11. Stevenson, R. and England, A. 1981 Draft outline of a pro­posed handbook on the organisation and methods of geo­logical fieldwork. Norwich, Norfolk College of Art and Tech­nology (for Association of Teachers of Geology) 4 pp. Study Group on Education and Field Biology 1963 Science out of doors. London, Longmans 240 pp. Thompson, D.B. 1974 The nature and assessment of fieldwork in geology. Bull. geol. Soc. Norfolk 26,3-46. Thompson, D.B. 1975 Types of geological fieldwork in relation to the objectives of teaching sdence. Geology 6, 52-61.

Thompson, D.B. 1979 Advanced level fieldwork Assessment. The JMB Scheme. Geology Teaching 4 (3), 92-107. Thompson, J.J. (Ed). 1975 Practical Work in Sixth Form Science. Oxford, Science Centre, Department of Educational Studies. 88 pp. Warnock, H.M. & Others 1978 Special educational needs; report of the committee of enquiry into the education of handicapped children and young people. London, Department of Education and Science (Cmnd 7212). 416 pp. Welsh Joint Education Committee 1969 General Certificate of Education. Fieldwork in Advanced Level Syllabuses in Geo­graphy, Geology, Biology, Cardiff, WJEC. 9 pp. West Midlands Regional Examining Board 1979 Notes of Guidance on the Organisation and Marketing of Fieldwork and Practical Work for candidates taking Geology in the CSE examinations 1978 and subsequent years. Birmingham, WMREB 12 pp. Wilson, V. 1974 The teaching of geology in schools. Proc. Geol. Ass. Lond. 58, 1-44.

D.B. Thompson, Department of Education, University, Keele, Staffs. ST5 5BG.

65

A NEW CONCEPT IN GEOLOGICAL STUDY

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THE SPECIMEN PROBLEM; ANOTHER SUPPLIER'S REPLY

Dear Editor,

It was with interest that I read Christopher Parkes' letter in Geology Teaching, September 1981 and Richard Tayler's reply in the subsequent issue. I also noted with interest an advert in that latter issue for South West Minerals Resources. My interest turned to wry amusement when I received a copy of their catalogue, and I cannot help but feel Christopher Parkes is regretting some of his earlier comments.

During nineteen years in the rock and mineral supply business, I have been asked by teachers unnumerable times how I justify charging x pence for a piece of rock which cost me nothing to collect. The answer is simple; it did not cost nothing to collect - it cost time, petrol and other expenses.

Mr. Parkes accused the suppliers of charging the earth for specimens. I don't know whose catalogue he looked at but I'm sure he didn't consult those of the half dozen or so specialist British suppliers. His letter impled that he was about to undercut everybody and hence my amusement on receiving his catalogue to discover that the majority of his prices are higher than mine.

I have seen a lot of people climb on to the geological band wagon only to fall off again when hit by the economic facts of life. I am all in favour of ATG members' taking the initia· tive because I rely on the initiative of several members in supplying me with further flung materials, but when a member takes the initiative to set up in business and then charges more than the established suppliers, does this help the "specimen problem"? Who is "charging the Earth(!?)" now?

Yours faithfu lIy,

Roger S. Harker, 2 Wellsic Lane, Rothley, Leicestershire LE770B

A STAFFORDSHIRE BLUE?

Dear Editor,

re Geology Teaching 7(1) 1982 p. 6

Seismometers in Gower Street detected a slight tremor recently, consistent with the dropping of a modest sized brick somewhere in Staffordshire.

Andrew Ramsay was our third Professor at University College, and as you quote, his year was divided between teaching in London (November to February), and mapping in North Wales. His biography (Geikie, 1895) lets us know that he rehearsed his lectures with some trepidation while completing

66

the mapping of Cader Idris. We also know that, however nervous he was at the prospect of facing students, at the end of his first year in teaching, he wrote,

"Got the composing steam well·up and finished the lecture by eleven. Got through it unusually well, and had a round of applause when it was all over."

Clearly, from the story you quote concerning the brick (one of which we heartily approve in Gower Street), he quickly learned what was expected of a Lecturer in radical and free· thinking University where students were no respecters of persons. We for our part, however, like to remember that Edward's name was GREENLY, and that no LAND, but rather a friendly 'HAND through Time', was the title of his plaintif autobiography. While History may be a Jade, the truth in this case rates a bit higher on the scale of hardness.

Best wishes,

Eric Robinson, Dept. of Geology, University College London, Gower Street, London WC1 E 6BT

(The Editor regrets that the proof·reading of this item was not what it might have been).

PRACTICAL WORK IN EARTH SCIENCES

Dear Editor,

I am at present making a compilation of practical activities which may be used for teaching Earth Science in the sec· ondary school, and I would be grateful for the opportunity to ask for suggestions via Geology Teaching.

I am especially interested in the less sophisticated techniques and activities which can be carried out by either pupils or teachers in a non'specialist classroom. Many of the simple but effective Earth Science practical activities have been published in a wide variety of journals, curriculum packages, textbooks and booklets and are not readily available to the hard pressed teacher. I hope to be able to remedy the situation somewhat, so I would be very grateful if readers of Geology Teaching could send me any ideas they may have.

Needless to say, due acknowledgement will be made in any subsequent publication. If a low cost duplicated booklet is produced, I would be only to pleased to send copies to con· tributors whose ideas have been included.

Many thanks.

Yours sincerely,

Roger Trend, Lecturer in Education, Division of Education, Floor 12, Arts Tower, University of Sheffield, Sheffield, S102TN.

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AN EARTH SCIENCE COURSE PART OF AN INITIATION INTO PHYSICAL SCI ENCE

Recently the Editor of ATG received a letter which appeared to include a belated desire to join the Association. The in­tending member apologised for his lack of appropriate qual­ifications - indeed he revealed that he had been trained as a doctor, had served as a ship's surgeon for a time, and had unsuccessfully sought jobs as a teacher for several years - but he explained that by chance he had been offered a job as a palaeontologist. He included a copy of an article which he had written and suggested that this might show that, in relation to ATG's objects as an Association, his heart was in the right place. His submission is reproduced very nearly verbatim:

INTRODUCTION "Nearly nine years ago, I was invited, ... to take part in a series of courses of Educational Lectures; which were intended to initiate young people in the elements of Physical Science.

My course was to be the first of the series; and I made use of the opportunity, thus afforded me, to put into practical shape the ideas, which I had long entertained and advocated, respecting the proper method of approaching the study of Nature.

It appeared to me to be plainly dictated by common sense, that the teacher, who wishes to lead his pupil to form a clear mental picture of the order which pervades the multiform and endlessly shifting phenomena of nature, should commence with the familiar facts of the scholar's daily experience; and that, from the firm ground of such experience, he should lead the beginner, step by step, to remoter objects and to the less readily comprehensible relations of things. In short, that the knowledge of the child should, of set purpose, be made to grow, in the same manner as that of the human race has spontaneously grown.

I conceived that a vast amount of knowledge respecting natural phenomena and their interdependence, and even some practical experience of scientific method, could be conveyed, with all the precision of statement, which is what distinguishes science from common information; and, yet, without over­stepping the comprehension of learners who possessed no further share of preliminary educational discipline, than that which falls to the lot of the boys and girls who pass through an ordinary primary school. And I thought, that, if my plan could be properly carried out, it would not only yield results of value in themselves, but would facilitate the subequent entrance of the learners into the portals of the special sciences.

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I undertook, therefore, to deliver twelve lectures, not on any particular branch of natural knowledge, but on natural phenomena in general; and I borrowed the title of "Physio­graphy", which had already been long applied, in a different sense, to a department of mineralogy, for my subject; inas­much as I wished to draw a clear line of demarcation, both as to matter and method, between it and what is commonly understood by "Physical Geography'~

Many highly valuable compendia of Physical Geography, for the use of scientific students of that subject, are extant; but, in my judgement, most of the elementary works I have seen, begin at the wrong end, and too often terminate in an omnium gatherum of scraps of a/l sorts of undigested and unconnected information; thereby entirely destroying the educational value of that study which Kant justly termed the "proplBdeutic of natural knowledge. "

I do not think that a description of the earth, which commences, by telling a child that is is an oblate spheroid, moving round the sun in an elliptical orbit; and ends, without giving him the slightest hint towards understanding the ordnance map of his own county; or any suggestion as to the meaning of the phenomena offered by the brook which runs through his village, or the gravel pit whence the roads are mended; is calculated either to interest or to instruct. And the attempt to convey scientific conceptions, without the appeal to observation, which can alone give such conceptions firmness and reality, appears to me to be in direct antagonism to the fundamental principles of scientific education.

"Physiography" has very little to do with this sort of "Physical Geography. " My hearers were not troubled with much about latitudes and longitudes; the heights of mountains, depth of seas; or the geographical distribution of kangaroos and Compositc!!. Neglecting such pieces of information-of the importance of which, in their proper places, I entertain no dOUbt-I endeavoured to give them, in very broad but, I hope, accurate, outlines, a view of the "place in nature" of a particular district in England, the basin of the Thames; and, to leave upon their minds the impression, that the muddy waters of our metropolitan river; the hills between which it flows; the breezes which blow over it; are not isolated phenomena, to be taken as understood because thev are familiar. On the

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contrary, I endeavoured to show that the application of the plainest and simplest processes of reasoning to anyone of these phenomena, suffices to show, lying behind it, a cause, which again suggests another; until, step by step, the con­viction dawns upon the learner that, to attain to even an elementary conception of what goes on in his parish, he must know something about the universe; that the pebble he kicks aside would not be what it is and where it is, unless a particular chapter of the earth's history, finished untold ages ago, had been exactly what it was.

It was necessary to illustrate my method by a concrete case; and, as a Londoner, addressing Londoners, I selected the Thames, and its basin, for my text. But any intelligent teacher will have no difficulty in making use of the river and river basin of the district, in which his own school is situated, for the same purpose . ..

I trust therefore that the book may be useful to both learners and teachers; but, I am most concerned, that the latter should find in it the ground-work of an introduction to the study of nature, on which their practical experience will enable them to erect a far better superstructure than that which I have been able to raise. "

THE CONTENTS OF THE BOOK

Chapter 1 2 3 4 5 6 7 8

The Thames Springs Rain and dew The crystallization of water; Snow and ice Evaporation The Atmosphere The Chemical Composition of pure water The chemical composition of natural waters

9 The work of rain and rivers 10 Ice and its work 11 The sea and its work 12 Earthquakes and volcanoes 13 Slow movements of the land 14 Living matter and the effects of its activity on

the distribution of terrestrial solids, fluids and gases - deposits formed by the remains of plants

15 The formation of land by animal agencies -coral land

16 The formation of land by animal agencies -foraminiferal land

17 The geological structure of the basin of the Thames; and the interpretation of that structure

18 The distribution of land and water 19 The figure of the earth - construction of maps 20 The movements of the earth 21 The sun

T.H. Huxley F.R.S. Professor of Palaeontology and Natural History, Royal School of Mines, Jermyn Street, London, 1877.

[Taken from the Preface (pp iii-ix) to: Huxley, T.H. 1877 Physiography - An introduction to the study of Nature. London, Macmillan, 384 pp. The book was reprinted nearly every year until c. 1900. The lecture course was first delivered at the London Institution in 1869 and repeated at South Kensington in 1870. The book was compiled from verbatim reports by an editor, Mr. F.W. Rudler, and corrected and rewritten by the Huxley himself.J

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69

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(COMMENT continued from page 71)

Association of Teachers of Geology 1977. The status of A level Geology. Geology Teaching 4(2), p. 49 only. Department of Education and Science 1982. Science Edu­cation in Schools. A consultative document. London, HMSO for DES and the Welsh Office, 12 PP.

CROSSWORD SOLUTION

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70

(COMMENT continued from back cover) the revision of curricula and examinations in geology at CSE and 0 level were very varied and far from satisfactory. Four CSE boards and one GCE board did not respond to the ATG enquiry and several replied defensively, giving little useful information. Both these postures provided a great contrast to the openness and sense of cooperation displayed by the best of the boards. Several CSE boards revealed that they had devel­oped no syllabuses between 1965 and 1977, others that they favoured only mode 1 or mode 3 syllabuses. Some boards had only the sketchiest of committees to vet the syllabuses and one board relied on its geography panel to do the job. It was disappointing that so few of the named examiners and committee members appeared to have participated very fully in furthering the interests of geological education beyond the confines of the boards' work. In some boards' committees, ATG and ASE members appeared to form a small minority. Added to this was the knowledge that some sketchily defined CSE and GCE syllabuses were easily 'got through' in one year without recourse to the use of many resources, the develop-. ment of many practical, experimental or field experiences, or the employment of fully qualified teachers (see ATG 1979, p. 49 for a definition of a fully qualified geology teacher). Moderators who vetted some mode 3 syllabuses spoke privately of the enormous difference between well presented, geologically competent, even novel, syllabuses, and those which consisted solely of a list of contents which related to an obsolescent kind of physical geography.

ATG has generally taken the view that if something is worth doing, then it is worth doing well, according to the most up-to-date criteria available. The advent of the GCSE allows each consortium to make a new start and to avoid the weak­nesses which geology has inherited. One wonders, however, whether the boards' administrators who are to be in charge of

any GCSE geology development exercises will have sufficient personal awareness and experience of the field to improve significantly upon past failings, for much has happened in geological education since 1977. One wonders whether the boards will have antannae pointing in the right directions and receivers tuned to the appropriate range of frequencies. Since only a few boards subscribe to ATG, we have a very con­siderable communications problem, which the Syllabus and Examinations Committee and the Council must tackle as a matter of urgency.

Meanwhile, is it too much to expect that the members of the GCSE geology working parties of each consortium will have been chosen because they have full geological and pedagogic qualifications, considerable experience of teaching geology and other science subjects, proven abil ity to stock and manage a laboratory and run a department, experience of planning science curricula according to modern principles, and a willing­ness to explain the decisions of committees to their colleagues in their local areas? Is it too much to hope that the chair­persons of such working parties will have worked regionally, and preferably nationally, and have taken steps to further the progress of geological education in the public arena? Is it too much to expect that most of those who are selected to sit on such committees will be longstanding members of ATG and ASE, and will have been vocal and active within local, regional or national teachers meetings for much of their careers? The ATG 1977 survey showed most emphatically that most of these criteria were not being met.

REFERENCES Anon 1982. Draft national criteria for science co-ordinating. Science coordinating working party report. Cambridge, Cambridge Local Examinations Syndicate for the GCE and CSE Board's Joint Council for 16+ national criteria. 7 pp.

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GEOLOGY GCSE 16+

The decision to implement a single system of examining at 16+ - the GCSE - was taken by government in February 1980. In choosing not to designate a national co-ordinating body to develop the new examination, the government placed' the responsibility in the hands of six examining consortia, four of which, apart from the Boards in Wales and Northern Ireland, were newly formed from an amalgamation of the existing GCE and CSE boards. The role of DES was to provide guid­ance and define areas of decision-making (see Phillips 1981). Late in 1980 the Joint GCE and CSE Boards established a Council for the development of National Criteria in order to guide curriculum development in each subject area, initially from December 1980 in eight subjects, later from May 1981 in a further 14 subjects.

As a minority subject geology was naturally enough not amongst the first or second 'wave' subjects and no national working party to establish criteria of guidance in geology is ever likely to be formed. Nevertheless the application of the criteria appropriate to general or integrated science may provide some guidelines to curriculum developers (Anon 1982). In addition the report of the initial explorations of one consortium, the Midland Group, may prove to be helpful (see Dutton 1982).

Notwithstanding these moves, however, GCSE geology must be seen in a wider context. Although the Secretaries of State for Education have recently welcomed the inclusion of geology in the 11-14 curriculum (DES 1982, p.2 and p.5).

EDITORIAL SUBCOMMITTEE

David Thompson (Editor) Geoffrey Brown (Assistant Editor) Bob Standley (Deputy Editor) Stephen Hannath (Primary School Geology) Dick Mayhew (Reviews) Robin Stevenson (Fieldwork) Frank Spode (Primary School Geology, Teacher Training) David Thompson (News, Shopfloor) Ray Harris (Advertising)

Opinions and comments in this issue are the personal views of the authc.rs and do not necessarily represent the views of the Association.

Advertising enquiries to: Ray Harris, 17 Caroline Buildings, Widcombe, Bath BA2 4JH.

Contributions for the next issue of GEOLOGY teaching will be welcome, and should be sent to the Editor, from whom notes for contributions are available.

Volume 7 Number 2 June 1982

72

tney are less forthcoming on the virtues of minority sciences in years 14-16. They are grappling with the problems of encouraging 'science for all' and providing both a balanced curriculum and a balanced science curriculum. At the moment 9% of boys and 17% of girls study no science in the 4th and 5th years; 50% and 60% respectively study one subject, leaving themselves unbalanced in other areas of science; 31% and 18% study two subjects leaving themselves a little less balanced with respect to the rest; 10% and 5% study three science subjects at the expense of missing out on a host of worthwhile educational opportunities outside the field of science. There is widespread agreement that all pupils should study some form of science for 10-20% (4 to 8 periods) of their time in the 4th and 5th years, but the problem of incor­porating experiences from all the sciences, without becoming superficial, is daunting. Possible solutions - physical science, unified science, core science and options science - are only at the discussion stage, and are likely to founder on the reefs of traditional attitudes. Whilst these matters are unsettled, ATG must continue to support the interests of those pupils and teachers for whom geology provides a great many exciting experiences relating to the understanding of a rapidly changing world in the late 20th century.

In the absence of national criteria to guide the development o. geology curricula at 16+, it is open to a subject association such as ours to comment on the arrangements which consortia make for both syllabuses and examinations, for in some regions in the past 20 years the encouragement of geology as a vehicle for a sound education for 14-16 year olds has not been taken very seriously. The ATG survey of 1977 (Geology teaching 2(3). p.150-155) revealed that the procedures for

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Published quarterly by the Association of Teachers of Geology.