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Manitoba from the Air
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Sand/Gravel Pit on the Assiniboine Delta

The Assiniboine Delta deposited into the west side of glacial Lake Agassiz is a massive accumulation of sand and gravel.[i] Coarse gravel near the apex east of Brandon gradually gives way to sand further east. The present-day Assiniboine River has etched a steep-sided meandering valley into the sands as it adjusted to a new base level with the retreat of Lake Agassiz. Here are two meander loops of the eastward-flowing Assiniboine River 1 eroded into sands which are exploited at a large pit 2 with two smaller ones to the north 3. In the large pit excavation has reached the water table resulting in flooding (dark-tone) of the bottom 4.

Other points to note on this photo are a) PTH 34 5 between Holland (to the south) and Austin (to the north) is cut into the sands of the delta 6; b) delta sands have been blown into dunes north of the river 7; these are now stabilized by a mixture of grasses (light-toned) 8, deciduous woodland (dark-toned) 9 and coniferous trees (identified by their triangular shadow) 10; c) the south side (north-facing side) of the Assiniboine Valley is heavily wooded by deciduous trees (dark-toned with rounded crowns) 11; d) fields that have been cleared for agriculture are medium-dark toned 12, indicating that the crops in them are still green and that the date of the photo is pre-harvest; and e) one field is in the process of being cultivated 13; the cultivated part of the field is darker-toned 14, and by using a magnifying glass with the original photo, the machine doing the cultivating can be seen 15.


[i] For a map of the location of the Assiniboine Delta see Corkery M. T. “Geology and Landforms of Manitoba” in Welsted, Everitt and Stadel op. cit.. 1996, figure 2.4, 18.

Figure 13.5

Sand/Gravel Pit on the Assiniboine Delta