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
3.97: Epinette Creek and Sand Dunes East of Shilo
In the western half of this panchromatic photo are two dune complexes 1 2; the northern one is completely stabilized, but the southern one is less so. The latter shows areas of very light-toned bare sand 3, but it is mostly grass-covered (light grey) 4 with an area of dark-toned coniferous trees, probably white spruce (Picea glauca), to the west 5. The northern complex is mainly grass-covered 6 with patches of deciduous trees, probably aspen (Populus tremuloides) 7, and isolated white spruce (Picea glauca) 8 identified by their dark tone and triangular shadow shape. Dune ridges bound the dune complexes 9, 10, 11. The central of the three shows an interesting variation in vegetation cover: the south side, with a dry microclimate, is bare or grass covered 12; the north, wetter side, is grass or tree-covered 13. A similar arrangement is seen on the northern ridge 11. Other indefinite stabilized dune ridges occur in the northwest 14.
East of the dunes Epinette Creek 15 occupies a dark-toned area 16—the path of a former distributary of the
In the northeast is a small patch of agricultural land 18. The CN line crosses the area in the north 19, and a light-toned path 20 can be seen in the east. This is probably used only by military vehicles as the area lies within the Shilo range and training area. A circular depressed area 21 east of the northern dune complex defies easy explanation. Less clearly defined circular features occur further south 22.
Figure 3.97: Epinette Creek and Sand Dunes East of Shilo
Vertical air photograph: A23692-116
Flight height: 13,700 feet a.s.l.; lens focal length: 153.22 mm
Date: May 12, 1974
Scale: 1:25,000 (approx.)
Location: Townships 9 and 10; Range 15 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62 G/14 Carberry