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
3.13: Slumping: Souris Gorge Between Souris and Wawanesa
East of Souris the southeastward flowing
The valley sides and the hummocky land 14 of the Tiger Hills are covered by deciduous woodland except for some areas cleared for cattle grazing 15. This contrasts with the flat land south 16 and north 17 of the valley that has been cleared for agriculture. These areas are underlain by glacial deposits, and to the north very minor northeast/southwest trending ridges 18 are picked out by the rain splash effect: rain splashes small-sized, dark-coloured fragments from crests, leaving behind coarse light-toned materials. To the west water-filled hollows 19 emphasize this topographic pattern.
Figure 3.13: Slumping: Souris Gorge Between Souris and Wawanesa
Vertical air photograph: A11046-57
Flight height: 9,520 feet a.s.l.; lens focal length: 6 inches
Date: May 21, 1947
Scale: 1:15,800 (approx.)
Location: Township 6, Range 18 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62G/12 Wawanesa