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
3.59: An Esker in Northeastern Manitoba
The main esker 1 traversing the area on this photo trends north-northeast/south-southwest and is 9 miles (14.5 km) long, but the 1:250,000 map of the area (64P
The Gordon River 7 flows in a general west to east direction across the area that is dotted by numerous lakes, variable in tone.
This area lies within the shrub sub-zone of the forest/tundra transition vegetation zone[i] in which “a shrub tundra like community dominates, together with small open clumps of white or black spruce in more sheltered sites.”[ii] On the photograph the wooded areas are the dark-toned patches lying mainly along the watercourses 14.
Figure 3.59: An Esker in Northeastern Manitoba
Vertical air photograph: A15460-17
Flight height: 30,000 feet a.s.l.; lens focal length: 154.3 mm
Date: August 21, 1956
Scale: 1:58,000 (approx.)
Location of centre point: 59° 28'N, 97° 06'W
Map sheets: 1:250,000 64 P Nejanilini
1:50,000 64 P/6 Fallis