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
3.99: Stabilized Dunes on the Assiniboine Delta Northwest of Holland
With the exception of two small areas in the northwest and southeast, virtually the whole area is covered by sand dunes developed on the Assiniboine Delta. In the northeast is a meander of the
Virtually all the dunes are stabilized, with the exception of a patch of bare sand in the west 8. This dune complex has a steep, wooded northeastern slope 9. Several dune ridges can be seen 10 with a general west-northwest/east-southeast trend in response to the prevailing wind. The stabilized dunes are covered by: 1) grasses that are light toned with smooth texture 11; 2) deciduous trees, probably aspen (Populus tremuloides) 12 that are darker toned and have a mottled texture; and 3) patches of, and individual, coniferous trees, probably white spruce (Picea glauca) 13 that are dark-toned with a triangular shadow.
Figure 3.99: Stabilized Dunes on the Assiniboine Delta Northwest of Holland
Vertical air photograph: A15577-15
Flight height: 20,000 feet a.s.l.; lens focal length: 153.09 mm
Date: October 11, 1956
Scale: 1:39,750 (approx.)
Location: Townships 7 and 8; Range 12 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62G/10 Treherne
[i] Scott, op. cit., 1996, 46.