A revision of the stratigraphy of the Lea Park formation in west central Saskatchewan

The Lea Park formation is an equivalent of the Upper Cretaceous Milk River and Pakowki formations of southern Alberta. Upper Cretaceous sediments of the Prairie Provinces are derived from land masses which bordered the Western geosyncline. Redistribution of Upper Cretaceous non-marine sediments from the seaward margin of deltas by epeiric sea currents resulted in the deposition of marine sand lenses within the mud-bottomed basin. Palaeontological criteria are the most helpful for distinguishing these marine from other non-marine environments. The Lea Park formation consists, between Lloydminster and Battleford, of four stratigraphic units. The basal shale unit contains the Epistomina caracolla microfauna. Overlying it is a shale characterized by Verneuilina bearpawensis. This is followed by a sand and sandstone facies with a marine megafauna. The fourth and highest member in the Lea Park formation is of marine shale. Upward the Lea Park formation passes into the Ribstone Creek, a brackish water arenite formation.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofGraduat