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
3.27: The Assiniboine Spillway, Assiniboine River, and a Cutoff
This low oblique photo, so called because no horizon is showing, is of one of the cutoffs 4 on the vertical air photo of Figure 3.26. The view is from the east, looking west across the
The wooded west wall of the spillway is seen in the foreground 1. The spillway runs across the photo with the river channel on the valley floor 2. The cutoff is in the centre 3, and another one is imminent 4. Meander scrolls emphasized by the woodland and snow cover are evident within the meander loop 5. The east side of the spillway is in the background, dissected by two steep-sided wooded gullies 6.
Figure 3.27: The Assiniboine Spillway, Assiniboine River, and a Cutoff
Low oblique air photo
Date: December 6, 1965
Scale: Variable-- larger in foreground, smaller in background.
Location: Township 12, Range 25 WI
Map sheets: 1:250,000 62F Virden
1:50,000 62F/15 Virden