The Swift Current Creek Beds, the Cypress Hills Formation, and the Wood Mountain Formation, all comprising fluvial deposits of Tertiary age, occur in southern Saskatchewan. They reveal in their primary directional structures, their changes in grain size, and their stream gradients, a northeasterly direction of stream flow for the ancient streams that transported and deposited the sediments.

The units consist of varying amounts of gravels and sands. The gravel component comprises mainly quartzites and chert, and in addition, pebbles of porphyritic rocks are present. The sands consist mainly of quartz, with some feldspar and ferromagnesian minerals. The most likely source for the sediments is the Rocky Mountains in northwestern Montana. This source accounts, in addition to the quartzites and cherts, for the presence of porphyritic pebbles.

The sediments of the three units are the only remaining evidence of deposition during a general period of erosion in southern Saskatchewan.

Two informal stratigraphic units, the "Redeposited Cypress Hills Formation" and the "Redeposited Wood Mountain Formation," are established to describe

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those deposits of gravel and sand, which are lithologically similar to the Cypress Hills and Wood Mountain Formations, but which occur at lower elevations. Their steep gradients towards the south, and the presence of directional structures indicating southerly flow, support the contention that they represent reworked material. These deposits, overlain by Pleistocene deposits, are regarded as Middle Oligocene to Late Pliocene in the Cypress area, and Late Miocene to Late Pliocene in the Wood Mountain and Willow Bunch Lake areas.

Local cementation of the formations is post-depositional, and is believed to be due to hydrologic conditions.

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