Search Textbook

Table of Contents
Foreword
Preface
Glossary

Chapter 3: Geologic Structure and Landforms

3.68: Assiniboine Delta Edge and Lake Agassiz Strandlines Near Miami

In this high-level, small-scale photo, the lakeward edge of the Assiniboine Delta deposited into glacial Lake Agassiz at the end of the ice age can be seen trending northwest/southeast across the area 1. This relatively steep slope is wooded and hence dark-toned. Three wooded stream valleys dissect the delta edge; from north to south they are South Tobacco Creek 2, an unnamed stream 3, and Shannon Creek 4. Thornhill Coulee 5 can also be seen in the southeast corner.

Northeast of the delta edge, several Lake Agassiz strandlines can be seen 6. The neutral term “strandline” is used because it is not clear whether they were deposited as beaches or offshore bars. Lake Agassiz retreated to the northeast, so strandlines in the west are at a greater elevation and earlier in origin than those further east. The strandlines stand out because of tonal variations that represent soil and land use variations. Although they are noticeable on the photo, their relief is only a metre or so, and they can easily be missed on the ground. East of the lowest strandline is typical very flat lake floor topography 7 with the only relief being the valleys of small intermittent streams 8.

The land is divided into the one-mile squares of the DLS system, and apart from the delta edge and some stream valleys, the land is intensively farmed, especially in the east where sections are divided into many fields 9. The hamlet of Miami 10 in the north is the only settlement in the area which is crossed by the east/west trending PTH 23 12. Elsewhere gravel roads follow section lines except where they cross the delta edge 13. The CN line 14 follows PTH 23 through Miami before veering off to the north to cross a strandline at an angle.

Figure 3.68: Assiniboine Delta Edge and Lake Agassiz Strandlines Near Miami

Figure 3.68: Assiniboine Delta Edge and Lake Agassiz Strandlines Near Miami

Figure 3.68

Vertical air photograph: A21852-10

Flight height: 24,100 feet a.s.l.; lens focal length: 85.55 mm

Date: August 12, 1970

Scale: 1:84,500 (approx.)

Location: Townships 3, 4, and 5; Ranges 5, 6, and 7 WI

Map sheets: 1:250,000 62G Brandon 

1:50,000 62G/8 Miami