North-central Alberta is a part of the Interior Plains of Western Canada, contains 1,550 square miles and is underlain by an average thickness of 7,500 feet of Paleozoic and Mesozoic sediments. Lower Cambrian, Ordovician, Silurian and Lower Devonian beds are absent.

Middle and Upper Cambrian beds are subdivided into eight lithologic units, and contain mainly epineritic stable shelf sandstones and carbonates which appear to be indicative of proximity to the Cambrian shorelines. The Cambrian strata have a maximum thickness of 1200 feet in the south and are truncated progressively northward by the pre-Devonian unconformity.

In contrast to the surface of the Precambrian unconformity, the surface of the pre-Devonian unconformity appears to have considerable relief.

The Middle Devonian Elk Point Group is subdivided into a Red Bed Unit, a Clastic and Evaporitic Unit and the Watt Mountain Formation. These units onlap westerly, are absent in the western part of the map area, and attain a thickness of 1,100 feet in the east. The depositional environment of the Elk Point Group apparently differed in the north and in the south: in the north the evaporitic facies pinch out abruptly against the land mass; in the south a broad westward facies change and thinning is indicated. Two feldspathic sandstone members of the Elk Point Group spread into the southern map area. The lower, the proposed Assineau Sandstone of this paper, forms a wedge up to 200 feet thick at the diachronic base of the Clastic and Evaporitic Unit. The upper, the Gilwood Sandstone, forms a sheet up to 60 feet thick and is developed within the Watt Mountain Formation. The sands appear to indicate transgressive periods of the Elk Point Group and both "shale-out" easterly.

The Elk Point sequence of the area discussed provides a continuous lithological correlation between the Elk Point section of central Alberta, described by Crickmay (1954) and that of northwestern Alberta, described by Law (1955).

The regional structure in north-central Alberta is homoclinal with gentle dips to the southwest.

Several prospective hydrocarbon reservoir beds are present in Cambrian sediments and in the Devonian Elk Point beds of the map area.

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