canada mapping report
DESCRIPTION
A bit of information about what I was up to this summer.TRANSCRIPT
G E O L O G I C A L M A P P I N G
O F
T I B B I T TT I B B I T T
L A K E L A K E
R E G I O NR E G I O N
JAC K R O B I N S O N
TIBBITT LAKE
1km
Area mapped
Ingraham Trail
LOCATION
Great Slave Lake
Ingraham Trail
Tibbitt Lake
30km
Great Slave Lake
1000km
INTRODUCTION
AND AIMS
I am a third year student at Queens’ college Cam-
bridge studying Natural Sciences and during the
summer I carried out a geological mapping project
as part of my course for the coming academic
year. The aim of the project was to map an area of
15-20 square kilometres of bedrock at a scale of
1:10,000 over 28 days. I was part of a four person
group made up of Cathy Smith, Max Winchester
and Sophie Lawson.
The area was within the Archean Slave province in
the Northwestern Canadian shield, approximately
65km Northeast of Yellowknife, where the Ingra-
ham Trail terminates at Tibbitt Lake (62.554 deg.
N 113.350 deg W). We stayed at Reid Lake camp-
site which was a modern camp ground with
shower and toilet facilities and was run by a very
friendly old Welsh couple.
Before the project began we knew some informa-
tion about what type of rocks to expect and we
had some contacts in the Geoscience office in Yel-
lowknife who had advised us on where to map.
Apart from that and a campsite reservation, we
didn’t know what to expect from the area or the
project. It was exciting!
Team Tibbitt in Yellowknife
Our camp-site with a sleepy Sophie taking a break.
Amphibolite on the right lies next to a layer of pale, baked sandy sediments. We believe the amphibolites here originally in-
truded the sediments as an igneus sill.
2013
OCT NOV DEC JAN
2012
FEB
JUL
Canada decided as target
country for mapping
project.
Valerie Jackson from GeoScience
office replied to email offering
advice about mapping in NWT.
Province decided. Further
planning and research required.
Tibbitt lake region decided as mapping area.
Begun to apply for grant money
July 10th- Flight leaves
Heathrow 11:05am arrives at Yellowknife at 23:02pm (but feels like 6am next day due to 7 hour time difference). Car hired and B&B found thanks to a friendly local.
First car hired, a sporty number
July 13th
Drive to
Campsite,
check in and
pitch tents.
Gravel sites…
July 14th- Day 1
of 28 mapping
days
Some spectacular views whilst mapping
July 18th
Encounter with a
black bear in the
field!
July 30th
Borrowed a canoe
to improve access
to remote
locations
TIMELINE
FEB MAR APR MAY JUN
AUG SEP
Begun to apply for grant money
Flights booked- trip beginning to feel like reality.
Campsite booked from 13th July until 18th August
2 week preparation mapping trip to the isle of Skye with university
August 16th - Last day
of mapping
August 19th – Return car and depart
Yellowknife
Aug 7th - Mapping
interrupted by punctured tire.
After a cautious journey back
to Yellowknife we got a new
car!
The spare tire was a bit thinner than the old one.
A hardened mapping team by the end.
TIMELINE
GEOLOGICAL
FINDINGS
Starting with the basics, geological mapping is the
process where you go into an area with a copy of
a topographic map (like an ordinance survey map
in the UK), locate your position on that map, using
a hand held GPS then identify the rock type that
you can see and mark it on the map. Additionally I
would make a note in my notebook about
interesting details of the rock and make a sketch if
it is particularly interesting. At every location I
would try to take the strike and dip of the rocks, if
they were sedimentary and were well exposed.
These measurements tell you what the strata or
sedimentary beds look like in 3D space and are
extremely useful for understanding any
deformation that has happened on a larger scale.
The red lines here
show the top of the
sedimentary beds.
Decreasing grain
size produces a
gradual colour
change in the beds.
The topographic
maps for our area
were digitally
available online so
we printed them out
on to card and took them out in to the field with
us every day. They were our field slips and for
each ‘locality’ that I made, there is a precise dot
on my field slip with a number next to it.
The number corresponds to the same number in
my notebook that has a greater description of the
rocks that I could see and any other interesting
features, as well as the important data and
labelled diagrams of relevance.
The area that I studied has been mapped before at
a very large scale of 1:250,000. I have mapped at
1:10,000 and will be able to produce a more
detailed map than anything available so far.
Classic turbidite beds of the
Burwash formation.
My field slips and notebooks at the end of the project.
An example page from
my notebook: The top
page is reserved for
labelled diagrams of
interesting features.
The bottom page
contains data on the
left, observations in
the middle and
interpretations of the
observations on the
right.
Over the course of 28 days
mapping (usually 9am-5pm) in the
field I managed to map an area of
roughly 10km2. One aspect of the
environment that made things
surprisingly difficult was the high
level of exposure. Because a lot of
the rocks were so excellently
exposed I initially found it difficult
to map at the right scale because
previous work has been in
Scotland where rocks might only
be exposed once every 100m or
so.
Rock Types
We found three major rock types
in our area, all of which had their
interesting features and
intricacies which made them
fascinating to map. There was the
Burwash formation, comprised of
Archaen meta-sediments,
including some pristine turbidite
sequences with flame structures,
graded bedding and cross bedding
preserved nicely in places. This
presented a challenge because it
has been greatly deformed, by
two major deformation events
that have led to both small and
large scale folding. Measuring the
strikes and dips of this unit was
thus of crucial importance.
The second major rock type was
the amphibolite- a dark, more
resistant unit composed of
amphibole and plagioclase
crystals that was sometimes
foliated, sometimes not and had
varying crystal sizes. Often it was
‘sill-like’, following the strike of
the surrounding Burwash
sediments and has been
interpreted as an intrusive
igneous rocks that has been
metamorphosed in a similar way
to the sediments around it.
Plotting the contacts of the
amphibole with the surrounding
sediments was challenging
because often it did not display
classic sill-like contacts but often
emerged, disappeared then re-
emerged at the surface. A
successful technique found
towards the end of the project to
map this well exposed but
complex unit was ‘traverse
mapping’ where I would traverse
across the whole unit, marking
contacts and which way the
contacts were going, then move
south 100m then traverse again.
Then at the end I could easily
connect the contacts measured
during the different traverses.
The final unit was a small area of
white granite that was exposed in
a sporadic way within the
Burwash formation,
uncharacteristic of granite which
is usually found in large plutons.
This exposure pattern suggested
to me that this could be the top of
a much larger body of granite that
lies beneath the surface. This
hypothesis however would need
more research to confirm or
refute.
CONCLUSIONS
Overall I thoroughly enjoyed the trip and I
believe I have developed a few skills along
the way:
Planning: We had to find an area by
ourselves, get there, get accommodation,
find topographic maps and all of the
equipment we would need.
Teamwork: In a group of four you have to
work together, especially with organisation in
order to make all of the different aspects
work. It is also important to get along well
which can be difficult when living in such
close quarters. Luckily there were no punch
ups!
Geological mapping skills: with only 2 weeks
of mapping experience before I have mapped
10km2 independently and will be able to
contribute new scientific information to the
world.
I loved camping and working in such a remote
part of the world. During the whole of our
mapping time, we did not see a single person
out in the field when we were working. The
worst part of being in the Northwest
Territories at that time of year were the
mosquitoes, especially just after it had rained
- they were everywhere so a combination of
bug spray and full body bug jacket were
needed to help reduce the number of bites.
I would highly recommend this type of
project to anybody doing geology, the more
remote and wild the better!
Max crosses the river using the bridge we built. Dedication.
Canoeing to the other side of the lake saved a lot of walking!