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Table of Contents
Foreword
Preface
Glossary

Chapter 3: Geologic Structure and Landforms

3.43: Spring Sapping Along the Banks of the Assiniboine River in Canadian Forces Base (CFB) Shilo

In this area, below Brandon, the Assiniboine River 1 has incised itself into the sands and clays of the Assiniboine Delta. The light tone of the river, caused by reflection from suspended sediment, contrasts with the dark tone of a cutoff with no suspended sediment 2. Spring sapping, where ground water comes to the surface at the junction of permeable sands above with impermeable clay below, has resulted in the retreat of the river’s north bank producing a scalloped edge 3 with occasional deeper embayments 4. On the river’s south side, scroll bars 5—some emphasized by trees 6—can be seen. Trees in the river valley are mainly deciduous with occasional patches of coniferous trees—mainly white spruce (Picea glauca)—identified by their dark tone 7 and conical shadow shape 8.

North of the river is a light-toned, grass-covered plain 9 with scattered dark-toned patches 10; these are clumps of creeping juniper (Juniperus horizontalis), a species that grows well on the thin sandy soil. Further north are stabilized sand dunes 11 with some poorly defined longitudinal dunes 12 that support dark-toned coniferous trees, mainly white spruce (Picea glauca). Other areas are covered by light-toned grasses 13 and medium-toned woodland 14, mainly trembling aspen (Populus tremuloides).[i]

Within the river bend land is used for agriculture, and a large gravel pit exists 15 that exploits gravel and sand left behind in scroll bars as the river migrated northwards. Land north of the river is part of Canadian Forces Base (CFB) Shilo and is used for military training. Two sand/gravel roads exist 16 as well as many light-toned paths 17 used to transport vehicles during military exercises.

Figure 3.43: Spring Sapping Along the Banks of the Assiniboine River in Canadian Forces Base (CFB) Shilo

Figure 3.43: Spring Sapping Along the Banks of the Assiniboine River in Canadian Forces Base (CFB) Shilo

Figure 3.43

Vertical air photo: A23692-29

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 7 and 8; Range 15 WI

Map sheets: 1:250,000 62G Brandon 

1:50,000 62G/11 Glenboro

Notes

[i] For details see Kerr, Rounds, and Welsted, op. cit. 1978, 408-414.