Devonian-Mississippian Boundary in Canadian Rocky Mountains: ABSTRACT

Abstract

Over most of the Alberta Rocky Mountain region, the Palliser formation, containing an Upper Devonian fauna, is overlain with disconformity by the Exshaw formation. The Exshaw, consisting of a lower black shale and an upper calcareous siltstone, has been considered to be Devonian but the faunal evidence of Devonian age is inconclusive. The Exshaw, though widespread, is not present throughout the region and in some sections the Mississippian Banff formation rests disconformably on the Palliser. The Exshaw occupies the same stratigraphic position and is lithologically similar to the Bakken of Saskatchewan. The Sappington of Montana which is reported to contain an early Mississippian fauna bears some lithological resemblance to the siltstone member of the Exshaw. It is sugges ed that the Devonian-Mississippian boundary be placed at the base of the Exshaw formation in the Alberta Rocky Mountains. End_of_Article - Last_Page 418------------