lithic analysis of stone tools. system to identify the type of stone tool created ~20 years ago by...

LITHic Analysis of stone tools

System to identify the type of stone tool Created ~20 years ago by Roger Grace Programmed using Macintosh’s Hyperstudio At the time it was tested by a group of

students◦ The students all came out with similar answers,

even when some of the values entered were different

LITHAN is a set way of identifying tools Also provides information on

◦ Blank type ( blade, bladelet, flake, chip, fragment or chunk)

◦ Flint knapping Technology ( blade, flake, Levallois)

◦ Hammer mode ( soft or hard )◦ Cortex

Takes 19 different attribute values Compares these values to the system rules Produces a screen with the conclusions on it

Two types of attributes used◦ Measured◦ Observed

Measured – values measured, normally using callipers

Observed – observed by the naked eye or using a low power microscope

7 measured attributes◦ Tool length◦ Tool width◦ Tool thickness◦ Mid-point width◦ Mid-point thickness◦ Platform width◦ Platform thickness

12 different observed attributes These normally have a screen with specific

options to select from These allows only certain values to be

entered

◦ Platform type◦ Lateral edges◦ Dorsal ridges◦ Cortex◦ Percussion◦ Butt◦ Bulb◦ Retouch◦ Position of retouch◦ Retouch type◦ Edge form◦ End form

If certain options are entered a screen automatically pops up to clarify observations and help with identification◦ Platform type = core◦ Retouch type = burin blow◦ Tool type = arrowhead◦ Tool type = microlith

Cards to clarify options when Platform type = Core

Cards to clarify when Retouch = Burin Blow

Card used when Type = arrowhead

Card used when type = microlith

LITHAN has ~ 30 pages of programming covering the rules in the system

Has two types of rules◦ General – applied all the time◦ Secondary – applied only if a specific conclusion is

previously reached

Rule to determine blank type If (length/width) > 2 and width < 12 mm Then Blank type = “Bladelet”

Rule to determine technology If Platform thickness < 5 and Platform type = “prepared”

and Lateral Edges = “parallel” and Dorsal ridges = “parallel”

Then Technology type = “Blade” Rule to determine hammer mode

If percussion = “no cone” and Butt = “un-lipped” and Bulb = “diffuse”

Then hammer mode = “soft”

Rule determining type of tool If (length – width) > 0 and retouch position =

“distal” Then type = “End scraper”

Secondary rule If type = “End scraper” and End form = “Round” Then type = “End scraper” Else if type = “End scraper” and End form =

“Carinated” Then type = “Carinated End Scraper

Functional Analysis of Stone Tools

Functional Analysis of Stone Tools Sister program to LITHAN LITHAN results can be used in the program FAST uses the information it gathers to

determine the wear on an artefact◦ Wear meaning what sort of material it was used

on◦ e.g.. Fish scale, hide, antler, bone, etc…

Takes in 20 different attribute values Uses fuzzy logic to calculate the best

possible answer Each attribute has allowable values which

are selected from a new card by the user

Three types of attributes◦ Measured◦ Macro Observed

Observation using low powered magnification ◦ Micro Observed

Observations made under high magnification

Edge angle Length Thickness Profile Shape

Gloss on the Edge wear Fractures – a count of them Fracture type Rounding – is the edge of tool rounded

Fractures and Fracture Type Rounding Micro topography Distribution Distribution type Invasiveness Linear features Striations Polish development

Some absent values can be used to determine use◦ E.g.. If the edge is not round, tool was probably

used on a softer material Other values, while present, are not

important for the determining of use◦ E.g.. Micro fractures are not diagnostic because

they can occur from any sort of contact motion

Once attributes are entered they are displayed on two cards◦ One for the Measured and Macro Observation◦ One for the Micro Observations

3 types◦ General ◦ Fuzzy ◦ Function

Attributes are used singlely or in combination◦ E.g.. (edge angle< 30°) then Angle = ‘cutting soft

material’◦ E.g.. (fractures = ‘absent’) and (edge angle > 30

and <60) then Angle = ‘medium material’ Conclusions reached by the rules are

Observations This Observations are then used in the

Fuzzy Rules

The fuzzy rules use the conclusions from the general rules

Each conclusion have specific numerical value placed on them according to the rules

The values are totaled to produce a score value

The score value is used in the function rules

Each variable (egg. Angle, length, profile) count as 2 (see the Macro Card)

If the surfaces’ (Ventral/Dorsal) have values the add 0.5◦ Unless “retouch”, “no polish”, or “no effect” Then

add 1 – because they are more telling ‘Non-Diagnostic’ = 0 All motion scores (except rotational) are

doubled

Use the Score values to determine◦ Function◦ Hardness of material◦ Type of Material

Function◦ E.g.. ‘cutting’ < 4 and ‘scraping’ > 8 and

‘grooving’ <2 and ‘whittling’ < 2 then function = ‘scraping’

Hardness◦ E.g.. (‘soft’ > 4 and < 8) and (‘medium’ >0 and <

2) and ‘hard = 0’ then hardness = ‘soft’ Type

◦ E.g.. ‘soft’ < 6 and ‘medium’ > 5 and ‘hard’ = 0 then type = ‘wood’

Type can also have more complex rules involving motion, and other values

Results are displayed on a single screen If unable to determine a value then

‘Insufficient Data’ is displayed Occurs in 2 cases normally

◦ Not enough use wear on tool◦ Use wear not consist with a specific use

LITHAN determines type of tool The value found by LITHAN and be put into

the FAST system FAST finds the use of the tool Both systems tested at Universities FAST has a 90% success rate during tests LITHAN tests have users coming up with the

same answers – even when some value are different for the same tool

Rules are cemented and written down Different people will still get the same

values

If rule is determined to be incorrect (e.g. Value given more weight then it should have) all findings have to be suspect

Different people will get the same result◦ Allows comparison without worry of results being

different because of the typologist LITHAN does not use Fuzzy Logic so the

answers it provides are presumed accurate◦ If not enough information is provided (i.e..

Because tool is broken or pieces are missing) then the value is designated “indeterminate”

Can update as new rules are found Records the tool type into a permanent

record

Does not provide a great deal of useful information◦ So it’s a scraper/arrowhead/other tool, big deal,

most past societies have these Most of the conclusions can be drawn from

eye sight

Runs a complex analysis quickly once values entered

Information is relevant to research◦ E.g.. Scraping hide implies hunting

Uses fuzzy logic, so have to be aware the answer is weighted

When designing the programs the creator had to think about three things◦ Facts to include◦ Rules to include◦ Storage of solutions

The facts◦ all contribute to the solution (e.g. colour of tool –

tells nothing of type or use of tool)◦ If too few – no accurate answer gained◦ If too many – spend so much time entering data,

easier to do it by hand

The rules ◦ if wrong or too vague then the system does not

provide an accurate answer◦ Have to provide for all possible cases◦ Must be updated if new information gained (e.g.

FAST has a lot of information about use wear as it is applied to fish scales because it was used in a Norwegian study that had fish scale wear on tools)

Storage ◦ Have to store answers for reference◦ Don’t want storage to be hard to search◦ Both LITHAN and FAST use Hypercard for this

LITHAN is a system that is useful in a limited area Helps with the consistency of identification of tools FAST is a system with a wider range of usefulness LITHAN while interesting is not helpful, other than in

a data gathering way – like a database FAST provides important information and shows the

reasoning behind a complicated process If the program the systems are written on was

updated the programs would be more useful

LITHAN and FAST use some of the same attributes◦ LITHAN has more in depth measurements of tool◦ FAST has micro observations

Might combine the 2 programs to run as one◦ LITHAN has a limited value, FAST is more useful

for studies◦ Would require the reworking of the rules

LITHAN Movie by Roger Grace◦ http://web.mac.com/rgrace2/ES/Movie.html

LITHAN; Grace, Roger◦ http://www.hf.uio.no/iakh/forskning/sarc/iakh/

lithic/expsys.html#anchor130219 FAST; Grace, Roger

◦ http://www.hf.uio.no/iakh/forskning/sarc/iakh/lithic/FAST.html