Search Textbook

Table of Contents

Chapter 3: Geologic Structure and Landforms

3.86: The Edge of the Assiniboine Delta Near Lavenham

The lakeward edge of the Assiniboine delta, seen trending northwest southeast across the photo 1, is steep, almost fault like. Here it stands 75 feet (23 m) above the flat land—the lake floor—to the northeast. Many small streams, which probably originate at a contact between clay below and sands above, flow northeast across the delta surface 2. They dissect the delta in a dendritic pattern 3 but almost all disappear soon after crossing the delta front 4, leaving the plain without surface drainage. Dendritic drainage patterns are characteristic of stream systems etched into rocks of uniform resistance to erosion such as sand, which is the case here.

Some land on the delta surface has been cleared for agriculture 5, but most of the creek valleys are still wooded—dark-toned—as is the delta face. The trees are deciduous and a few are light-toned 6 due to the aspen leaves changing colour, indicating a fall photo. In the southwest are sand dunes 7, mostly stabilized by grasses and trees but with a few patches of bare sand 8. Similarly some land on the northeastern plain is devoted to agriculture, but a surprising amount of woodland remains. In one field stubble is being burned 9, a common practice in the fall at the date the photo was taken. Smoke can be seen drifting northwards indicating a southerly wind at the time. A dark patch 10 near the northern edge of the photo probably results from burning. As is usual in southern Manitoba, sections and quarter sections of the DLS system can be seen. Roads follow section lines with some variations due to the topography 11. The CN line 12 runs across the southern edge of the photo past the small settlement of Lavenham 13.

Figure 3.86: The Edge of the Assiniboine Delta Near Lavenham

Figure 3.86: The Edge of the Assiniboine Delta Near Lavenham

Figure 3.86

Vertical air photo: A15577-66

Flight height: 20,000 feet a.s.l.; lens focal length: 153.09 mm

Date: October 11, 1956

Scale: 1:37,300 (approx.)

Location: Townships 9 and 10; Ranges 9 and 10 WI

Map sheets: 1:250,000 62G Brandon 

1:50,000 62G/15 MacGregor