Type Locality:

Type well Union Red Earth, in Lsd. 3, Sec. 13, Twp. 87, Rge. 8W5M, between cored interval 1,472.3 and 1,486.8 (4,829 and 4,877 ft).

Distribution:

It is zero to 182 m (597 ft) in thickness and is distributed for a great distance to the north and east of the Peace River Arch and a lesser distance south of the arch. In the Red Earth area the Granite Wash reaches over 76 m (289 ft).

Lithology:

The Granite Wash in the type well is subdivided into three members, in ascending order as follows: Granite Wash A, Granite Wash B and Granite Wash Shale Members. Granite Wash A Member, 1,480.3 to 1,486.8 m (4,855 to 4,877 ft): Arkosic sandstones and conglomerates of coalescing alluvial fans. Sands are poorly sorted, grain size grading from fine to very coarse, with granules common and occasional small cobbles. Sediments are oxidized, lack organic matter and contain only rare fossils. Among common sedimentary structures are medium to large scale cross-bedding and planar stratification. Thickness of the unit may exceed 30 m (98 ft). Sands are massive, and their geometry varies from lenticular to wedge-shaped. The sands are mainly composed of quartz and feldspar with mafic minerals, e.g., biotite and muscovite. Granite Wash B Member, 1476.3 to 1480.3 m (4842 to 4855 ft): Very similar to Granite Wash A, with the exception that sands are cleaner, well sorted and are composed of orthoquartzites. Granite Wash Shale Member, 1472.3 to 1476.3 m (4829 to 4842 ft): A shale unit of playa-lake origin. The lower unit is composed of mottled red-brown shales that are slightly anhydritic. The upper unit is a clean grey-green shale, non-fissile, sometimes containing fresh water limestone stringers.

Relationship:

The Granite Wash is the basal sand of a Middle to Upper Devonian Sea transgressive on the Peace River Arch, and flanks the arch at various stratigraphic levels. It is overlain disconformably by Middle to Upper Devonian beds in an onlap relationship progressively toward the arch. The Precambrian is overlain nonconformably by Granite Wash B.

Other Citations:

Baillie, 1956; de Mille, 1958; Goodman, 1956; Greenwalt, 1956; Guthrie, 1956; Newland, 1950; Sabry, 1989; Sproule, 1956.