eskers and drumlins are best recorded on winter imagery because the low
sun angle accentuates the morphological forms. Lacustrine deposits,
ground moraines and organic deposits, are best seen in summer as it is
possible to recognize' vegetation patterns on these deposits, in contrast
with the structure patterns of bedrock (Figures 2a and 2b).
Satellite imagery has been essential in the planning, field work
and final mapping stages of the project, but it has not been used
independent of other data sources. The following is a brief description
of the procedure employed in the program:
Step 1: Reversing the procedure traditionally employed in such an
undertaking, satellite imagery permits one to approach the problem from
the general to the specific, thus providing a better perspective, or
overall understanding, and effecting an enormous saving in time during
the initial stage. Therefore, satellite imagery is employed first to
distinguish the major landforms and to delineate their extent (Palabek-
iroglu, 1973). When the investigator is aware of the general distrib-
ution of surficial geology features, each step from that point onward can
be a calculated step. He can fit more detailed information within the
framework to elaborate the description of the surficial features and to
confirm or modify their delineations. This is the stage at which the
strategy of the work is planned. The value of Landsat for such planning
is better appreciated if one realizes that the mapping area covers half-
a-million km^.
Step 2: Aerial photography at a scale of 1:60,000, which is available
for the mapping area, is adequate for detailed mapping of the features.
However, there are over 7,000 photographs. If the photographs alone
were used, the investigator would be in the position of missing the
forest for the trees. Today, the general locations of ground sampling
stations are determined from the satellite imagery, then aerial photo-
graphs are used to pinpoint the exact site where a stop is to be made.
From 80 to 100 sites are marked within an area covered by one map sheet;
in practice, as the similarity between sites is confirmed in the field,
the number of samples may drop to 50, or may increase if warranted by
the conditions encountered.
Step 3: As the region is inaccessible by ground transportation, a
helicopter must be used for carrying out the field survey. Navigation
in remote areas is facilitated by determining one's position on a
Landsat image rather than on topographic maps since forests, burned
and ‘regenerated areas, rock outcrops, and individual bogs and fens, can
be used as reference features as well as the rivers and lakes depicted
on the topographic maps.
During the field survey, a description of the morphology and
vegetation cover of each site is tape-recorded and ground photographs
are taken. In addition, samples of unweathered material, 1.5 meters
below the surface, are taken and a short description of the soil profile
of each sample is noted. In areas covered with bogs and fens, samples
Figur
Figu1
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Lake