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
3.65: Outwash Plateau South of the Qu’Appelle River
The photograph shows an extensive area of outwash deposits, west of the
The outwash forms a plateau with abrupt edges 7. To the north and southwest, trees are more abundant in a wetter environment probably resulting from water reaching the surface at the contact between permeable sands and gravels above with less permeable clay below. The Qu’Appelle River 8 runs west to east across the north of the area, occupying a steep-sided 9, flat-floored spillway. It meanders freely across the spillway floor leaving behind six clearly defined oxbows 10 as well as one abandoned river segment 11 and numerous less distinct older abandoned channels.
In contrast to many previous photos the DLS system is not obvious but several faint section lines 12 and quarter section lines can be seen. The fifth base line of the DLS 13 separates townships 16 and 17. PTH 41 14 between McAuley (off the photo to the south) and St. Lazare (off the photo to the north) runs across the area. Light-toned areas 15 are road cuts where PTH 41 descends the steep south bank of the
Figure 3.65: Outwash Plateau South of the Qu’Appelle River
Vertical air photograph: A15530-13
Flight height: 20,000 feet a.s.l.; lens focal length: 152.26 mm
Date: October 9, 1952
Scale: 1:39,700 (approx.)
Location: Townships 16 and 17; Range 29WI
Map sheets: 1:250,000 62K Riding Mountain
1:50,000 62 K/6 Birtle