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Chapter 3: Geologic Structure and Landforms

3.8: Joint Zones South of Lamb Lake

Often vegetation obscures the bedrock geology, but in some cases the vegetation is a reflection of the geology. The photo shows an area of flat, mainly wooded land between South Moose Lake and Cedar Lake in central Manitoba. “Lines of trees disclose the location of joint zones (joint zones are numerous closely-spaced individual parallel and on echelon joint planes, which, because of their number and close spacing are accentuated by longtime weathering and erosion). Because the closely spaced joints weather and erode differentially in flat-lying Silurian dolomite terrain, they offer a better environment for growing trees than nearby areas where the joints are widely spaced.”[i] Two prominent lines of joint zones trend west-northwest/east-southeast 1 and northeast/southwest 2 intersecting at a 45° degree angle 3. Part of the south shore of Lamb Lake 4 coincides with the west-northwest/east-southeast trend. In the northwest is Ranchers Creek 5.

Figure 3.8: Joint Zones South of Lamb Lake

Figure 3.8: Joint Zones South of Lamb Lake

Figure 3.8

Vertical air photograph: A19767-87

Flight height: 8,920 feet a.s.l.; lens focal length: 152.16 mm

Date: September 16, 1966

Scale: 1:16,500 (approx.)

Location: Township 54, Range 19 WI

Map sheets: 1:250,000 63F The Pas

1:50,000 63F/9 Lamb Lake


[i] Mollard, op. cit., plate 10.19a