Table of Contents
2: Location, Borders, and Lakes
3: Geologic Structure and Landforms
6: Pre-historic and Early Historic Settlements
7: Survey Systems
8: Southern Hamlets, Villages, and Towns
9: Mennonite and Hutterite Settlements
10: First Nations Settlements
11: Northern Settlements
12: The Southern Cities
13: Mining and Oil Extraction
15: Industry / Manufacturing
16: Water Resources
17: Parks, Recreation, Sports
18: Transport and Communications: Past and Present
19: Legal Issues and Law Enforcement
3: Geologic Structure and Landforms
Click for chapter introduction
Geologic interpretation of images begins with the identification of lineaments, “regional linear features caused by linear arrangement of regional morphological features such as streams, escarpments, and mountain ranges and tonal features that in many areas are the surface expressions of fractures or fault zones.”[i] The emphasis in this section is on geologic structures and landforms, both of which can be easily identified on air photographs and other images.
The sequence followed here is that often found in geomorphology books. Geologic structures and structurally controlled landforms are illustrated first, followed by images of mass wasting and of the results of the agents of erosion—running water, ground water, ice, wind and the sea. The meandering rivers of southern Manitoba are excellent examples of that river form. Several of them have deposited deltas into lakes. The effects of ground water are less easily illustrated, but examples of spring sapping and artesian erosion exist in the south. As all of Manitoba was covered by ice during the latest glaciation, examples of glacial erosion, and especially of glacial deposition, are widespread. Equally impressive are the suite of landforms created by the large glacial lakes that appeared as the ice melted. Glacial spillways, glacial lake deltas, strandlines and flat lake floors are found in many places. Wind action has created dunes on some of the deltas and on glacial outwash deposits. The Hudson Bay coast is rising as a result of isostatic rebound, recovery from the weight of the ice. One result is the existence of strandlines many metres above the level at which they were created. Finally Manitoba’s great lakes are large enough to illustrate many of the landforms normally associated with sea coasts.
[i] Lillesand, T. M. and Kiefer, R. W. Remote Sensing and Image Interpretation (Third Edition). New York: Wiley, 1994, 179.
3.78: Souris Spillways South of Melita
In this area, just north of that shown in figure 3.77, the Souris spillway splits into a series of channels. The present-day Souris 1 occupies one of them; another to the east 2 known locally as Blind River Valley, is occupied by a small intermittent stream—Blind River 3. The higher land between the main channel and Blind River Valley 4 is known as “The Peninsula.” A similar piece of land 5 between Blind River Valley and another spillway channel 6 is “Granite Hill.” Clearly at one time water occupied all the spillway channels—probably simultaneously—but it eventually concentrated into what is now the Souris Valley, the floor of which is at a slightly lower level than the others. The main Souris spillway is steep-sided (7 and 8) and flat-floored with the river meandering freely across the floor. Several cutoffs 9 can be seen and another is imminent. Recent satellite images show that the river has now cut through this narrow meander neck 10. One cutoff 11 is peculiar in that it “faces the wrong way”—it was abandoned when the Souris flowed on the west side of the spillway rather than on the east side as it does today. The Souris is joined from the southwest by the Antler River 12 which has a more nearly v-shaped valley.
Most of the area has been cleared for agriculture with little natural vegetation remaining except patches of deciduous woodland in some meander loops on the spillway floor 13, in the Antler River Valley 14, and in bluffs on the spillway sides 15. It is noticeable that arable agriculture tends to avoid Blind River Valley; it is probably used for pasture, hence the dugouts 16 located in it. In this windy dry area of southwestern Manitoba, dugouts—small black rectangles on the photo—for water supply are ubiquitous 17, and in two locations 18, field shelterbelts planted to reduce wind erosion, can be seen. Farms, almost always with shelterbelts are distributed throughout the area 19.
Aspects of the DLS system are printed on to the landscape. The border between township 2 and 3 20 runs through the area. It is a correction line and in this western location (ranges 26 and 27) is about 1.25 miles (2 km) 21. The correction accounts for the bend in PTH 83 22. Note that the jog is only 0.25 mile 23 rather than the whole 1.25 miles. PTH 83 is joined by PTH 3 24 from the west. In the north PTH 83 veers northeast to parallel the pre-existing CP line 25.
Figure 3.78: Souris Spillways South of Melita
Vertical air photo: A24966-09
Flight height: 16,783 feet a.s.l.; lens focal length: 85.32 mm
Date: June 28, 1978
Scale: 1:54,200 (approx.)
Location: Townships 2 and 3; Ranges 26 and 27 WI
Map sheets: 1:250,000 62F Virden
1:50,000 62F/3 Gainsborough