Chapter 3: Geologic Structure and Landforms
Geologic interpretation of images begins with the identification of lineaments, “regional linear features caused by linear arrangement of regional morphological features such as streams, escarpments, and mountain ranges and tonal features that in many areas are the surface expressions of fractures or fault zones.”[i] The emphasis in this section is on geologic structures and landforms, both of which can be easily identified on air photographs and other images.
The sequence followed here is that often found in geomorphology books. Geologic structures and structurally controlled landforms are illustrated first, followed by images of mass wasting and of the results of the agents of erosion—running water, ground water, ice, wind and the sea. The meandering rivers of southern
3.60: The Russell Esker Near the Caribou River in Northeastern Manitoba
The water body on the right 1 is Long Lake, part of the Caribou River system that flows into Hudson Bay about 25 miles (40 km) to the east. A prominent esker 2 can be seen trending southwestward from the shore of the lake. Its total length is about 18 miles (29 km) less than half of which is shown on the photo. It is prominent enough that is has been named the Russell Esker. In common with many other eskers in northern
This area is in the shrub zone of the forest/tundra transition vegetation zone[ii] in which a “shrub tundra like community predominates.”[iii] On the photograph the shrub areas 5 are slightly darker-toned than the surrounding areas.
Figure 3.60: The Russell Esker Near the Caribou River in Northeastern Manitoba
Vertical air photo: A14678-106
Flight height: 30,000 feet a.s.l.; lens focal length: 152.7 mm
Date: July 2, 1955
Scale: 1:59,000 (approx.)
Location of centre point: 59° 26'N, 95° 31'W
Map sheets: 1:250,000 54 M Caribou River
1:50,000 54 M/5 Gross
[i] Wilson and Aykroyd, op. cit. n.d., 138.
[ii] Scott, op. cit., 1996, figure 4.2, 45.
[iii] Scott, op. cit., 1996, 53.