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Chapter 3: Geologic Structure and Landforms

3.81: The Souris-Pembina Spillway South of Darlingford

The spillway can be seen trending northwest/southeast and deeply entrenched (300 feet, 91.4 m) into the surrounding landscape. It differs from spillways shown previously in that although it is steep-sided, it has a narrow floor into which the Pembina River 1 is incised. In the northwest the spillway has migrated northwards, leaving behind a wide terrace 2. Land here has been cleared for agriculture, whereas both the north side 3 and south side 4 of the spillway are covered by dark-toned deciduous woodland. The Pembina River meanders but is not freely meandering from side to side of a flat spillway floor. It is joined from the north by the Little Pembina River 5 which is also in a steep-sided, wooded valley; several minor creeks 6 join from the south. Land both north and south of the spillway is typical hummocky ground moraine topography.

This photograph shows the Canada/U.S.A. border 7 with North Dakota south of the line. Similar, but different, land division systems exist in the two countries. Many different baselines are used in the U.S.A., whereas only one—the 49th parallel—is used in Canada. The baseline used for this part of North Dakota results in only partial sections in the northern tier south of the Canadian border 8. The principal meridians used in the U.S.A. are also different from those in Canada resulting in sections in Canada being offset from those in the U.S.A. 9. This accounts for the bend on a north/south road (PTH 31 in Canada) as it crosses the border 10. In Canada roads follow section lines except where they cross the Pembina Valley (11 and 12).

Figure 3.81: The Souris-Pembina Spillway South of Darlingford

Figure 3.81: The Souris-Pembina Spillway South of Darlingford

Figure 3.81

Vertical air photograph: A21821-61

Flight height: 24,000 feet a.s.l.; lens focal length 85.55 mm

Date: August 10, 1970

Scale: 1:79,200 (approx.)

Location (in Canada): Townships 1 and 2; Ranges 7 and 8 WI

Map sheets: 1:250,000 62G Brandon

1:50,000 62G/1 Morden