Fossil Zones of Devonian of Alberta

Abstract

Devonian strata are known to underlie the greater part of the Great Plains region of Alberta, though generally covered by a thick succession of later rocks. The Devonian rocks are exposed along the fringes of the Plains area where the later rocks have been eroded or where orogenic movements have brought them to the surface. The exposed Devonian rocks have been studied for index fossils which will be helpful in elucidating the various formations penetrated in the Plains area by oil-well operations. The following zones are suggested for the Upper Devonian in descending order: (a) Tornoceras, (b) Cyrtospirifer, (c) Coral, (d) Spirifer jasperensis (divided into two subzones), and (e) Stromatoporoid zone. Apparently the Middle Devonian is not widely spread under the Great Plains. It appears to be accompanied by salt-bearing beds in many places. A few genera and species are suggested for diagnostic purposes, such as Stringocephalus, Atrypa of different species, and Martiniopsis.