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.
3.57: Drumlinized Ground Moraine South of Holland and Treherne
Nowhere in southern Manitoba are found the classic “inverted spoon” shaped drumlins described in many elementary textbooks. However, immediately south of Holland 1 and Treherne 2 is an area of drumlinized ground moraine. Ridges composed of glacial till have a northwest/southeast alignment 3. The resulting topography has a rolling form—characteristic of drumlin areas—with an amplitude of relief up to 150 feet (46 m)—substantial for southern Manitoba. Lakes are not abundant; the only one large enough to be named on the 1:250,000 map, Pinkerton Lake 4, is south of the main drumlinized area.
The land north of a line joining Holland and Treherne is flat, part of the Assiniboine Delta. Cutting across the northern edge of the drumlinized area is a deep depression 5, up to 100 feet (30.5 m) below the surrounding land. It contains two intermittent lakes 6 and 7 hardly visible on the photo because they were dry at the time. Water from these drains into the Boyne River 8 that bypasses Treherne to the northwest. This lowland is clearly superimposed upon the drumlinized area; it is therefore later in origin, probably originating as the valley of a distributary of the Assiniboine at the time its delta was formed. Near the northern edge a deep gully, Bears Paw Gulch 9, is etched into the deltaic deposits.
On this high-level, small-scale photo, the sections of the DLS system are clearly visible, especially on the flatland of the delta, which is devoted to arable agriculture. Farmsteads with surrounding shelterbelts 10 are clearly visible. A correction line of over 0.25 mile (0.4 km) exists between townships 6 and 7 11. Correction lines, which are located between townships 2 and 3, 6 and 7, 10 and 11, etc., exist to compensate for the convergence of the meridians (on which range line are based), whereas north/south section lines are always one mile apart.[i] The correction line influences the location of PTH 34 12, which runs along a section line in township 6, then jogs westward by the correction distance and the width of an additional section 13 before continuing northward. The main east/west road is PTH 2 14 that bypasses both Treherne and Holland. The CP railway line follows the same route, except that it runs through both villages 15. All the roads in Treherne 2 are parallel or at right angles to the railway, whereas in Holland 1 the older roads are oriented with respect to the railway line; but newer roads in the south follow the lines of the DLS system.
Figure 3.57: Drumlinized Ground Moraine South of Holland and Treherne
Vertical air photo: A21666-219
Flight height: 23,400 feet a.s.l.; lens focal length: 88.611 mm
Date: July 21, 1970
Scale: 1:75,400 (approx.)
Location: Townships 6 and 7; Ranges 10 and 11 WI
Map sheets: 1:250,000 62G Brandon
1:50,000 62G/10 Treherne
[i] For details see Richtik, J. M. “The Township and Range Survey System” in Welsted, Everitt, and Stadel, op cit. 1996, 102-103.