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Chapter 3: Geologic Structure and Landforms

3.65: Outwash Plateau South of the Qu’Appelle River

The photograph shows an extensive area of outwash deposits, west of the Assiniboine River and south of the Qu’Appelle Valley in the extreme west of Manitoba 1. Outwash sediments were deposited by water running from melting ice. This usually results in a surface with a rippled appearance as seen in the south 2, but in the north the surface is flat 3. Outwash deposits in Manitoba are usually too dry to be suitable for arable agriculture. Most of the surface is covered by medium-toned grass 4 but some wetter areas support trees—dark-toned 5. Circular dark patches 6 are probably clumps of creeping juniper (Juniperus horizontalis).

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 Qu’Appelle spillway. PR 545 16, a faint light-toned line, runs east/west. North of the Qu’Appelle River, the CN railway line runs along the foot of the north bank of the spillway 17 with sidings into a large light-toned gravel pit 18.

Figure 3.65: Outwash Plateau South of the Qu’Appelle River

Figure 3.65: Outwash Plateau South of the Qu’Appelle River

Figure 3.65

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