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
3.63: The Arrow Hills From the Northeast
This oblique photograph—technically called a low oblique because the horizon is not shown–was taken looking towards the southwest. The main ridge of the hills can be seen in the middle ground 1 with the course of a small stream—dark-toned—to the west 2. In this winter image, the sun angle is very low, producing long shadows 3. There is a thin snow cover over most fields resulting in the very light tone, although part of the field in the foreground has been blown clear revealing the dark-coloured chermozenic soil of the area 4. PR 254 5 has also been kept clear by vehicular traffic.
Figure 3.63: The Arrow Hills From the Northeast
Oblique (low) air photo
Date: December 6, 1965
Scale: 1:18,600 in the foreground, decreasing to the rear
Location: Township 10; Range 24 WI
Map sheets: 1:250,000 62F Virden
1:50,000 62F/15 Virden