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Chapter 3: Geologic Structure and Landforms

3.23: Dissection of a Till Plain Near Foxwarren

In geological terms much of the land surface of southern Manitoba is very new, dating from the retreat of the last ice sheet no more that about 10,000 years ago. In the area shown, river channels are etching valleys in a till plain deposited during the Wisconsinan ice age. Snake Creek, a tributary of the Assiniboine—just off the photograph to the southwest—has already created a deep well-defined valley 1 wandering through the western side of this area. The steep-sided, flat-floored nature of the valley in the north 2 suggests that it used to carry much more water. Small creeks, tributary to Snake Creek, are gradually dissecting the till plain by headward erosion 3, and in at least two places, 4 small dams have been built either to prevent erosion or to catch water for agricultural use, or both. Several dark-toned lakes and sloughs have not been integrated into the drainage system 5. Much of the land in the south and west is still covered by deciduous forest, but in the north and east more land has been cleared for agriculture. Because of the irregular topography, fields are smaller than is often the case in southwestern Manitoba. The land is subdivided according to the DLS system, but roads do not follow all section lines, and the direction of some roads is clearly topographically determined 6. The CPR 7 line connects Birtle, just off the photo to the south and Foxwarren 8 in the north. As is commonly the case in small Manitoba settlements, the roads in the latter are parallel and at right angles to the railway line.

Figure 3.23: Dissection of a Till Plain Near Foxwarren

Figure 3.23: Dissection of a Till Plain Near Foxwarren

Figure 3.23

Vertical air photograph: A15530-50

Flight height: 20,000 feet a.s.l.; lens focal length: 152.26 mm

Date: October 9, 1956

Scale: 1:36,800 (approx.)

Location: Townships 17 and 18, Range 27 WI

Map sheets: 1:250,000 62K Riding Mountain

1:50,000 62K/6 Birtle