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Table of Contents
Foreword
Preface
Glossary

Chapter 3: Geologic Structure and Landforms

3.16: Slumping in the Souris Valley Below Wawanesa

In the area of Wawanesa, the meandering Souris River has incised itself down through surficial glaciofluvial and glacial deposits into the underlying Cretaceous shales. These two photographs illustrate the value of sequential air photos (photos taken of the same area at different times) in documenting changes even in the case of relatively slow changes such as those caused by geomorphological processes.

a)  1945 photo: Incised meanders of the Souris River can be seen with river cliffs on the outside 1 and slip-off slopes on the inside 2 of bends. Lateral erosion by the river has resulted in slumping at two locations 3, but east of Wawanesa the south bank 4 appears to be stabilized by thick woodland.

b)  1981 photo: This photo shows the course of the Souris 1 and a very clearly defined abandoned meander 2 still with some water in it but now well above the river level. Slumping has occurred on the south side of the river 3 since the 1945 photo was taken. The slump has a steep back wall 4 and an irregular main body 5 that causes a slight northward bulge of the river channel. 

Figure 3.16.a: Slumping in the Souris Valley Below Wawanesa, 1945 photo

Figure 3.16.a: Slumping in the Souris Valley Below Wawanesa, 1945 photo

Vertical air photo: A11123-309

Flight height: 12,400 feet a.s.l.; lens focal length: 8 inches

Scale: 1:17,000 (approx.)

Date: 1945

Location: Township 7, Range 17 WI

Map sheets: 1:250,000 62G Brandon

1:50,000 62G/12 Wawanesa


Figure 3.16.b: Slumping in the Souris Valley Below Wawanesa, 1981 photo

Figure 3.16.b: Slumping in the Souris Valley Below Wawanesa, 1981 photo

Vertical air photo: 8123 00-295

Flight height:  lens focal length:

Scale: 1:9,600 (approx.)

Date: 1981

Location: Township 7, Range 17 WI

Map sheets: 1:250,000 62G Brandon

1:50,000 62G/12 Wawanesa