Stratigraphy of the lower volcanic rocks in the southern part of the Absaroka Range, Wyoming / Стратиграфия нижних вулканических пород в южной части хребта Абсарока, штат Вайоминг

The present study is a report on the volcanic deposits which form the southern part of the Absaroka Range and which occur in the adjoining region in northwestern T/yoraing* This investigation has been undertaken with the object of eliminating discrepancies in correlation within the lower subdivisions of the Absaroka Range, chiefly between the Bighorn and Wind River basins. The results seem to demonstrate that the volcanic deposits which occur in the Lower Eocene Wind River formation of the 7/ind River Basin are probably equivalent in age and similar in composition to the Early Acid Breccia of Yellowstone Park. Analogous deposits sire apparently absent in strata of the same age in the Bighorn Basin. The Middle Eocene Early Basic Breccia, which is the basal volcanic subdivision of the Absaroka Range bordering the Bighorn Basin, is very probably equivalent to the Middle Eocene Aycross formation of the northwestern corner of the Wind River Basin. The Late Basic Breccia, which borders the Bighorn Basin, is here essentially correlated with the Upper Eocene Tepee Trail formation of the southern margin of the Absaroka Range. The Oligocene Wiggins formation of the southern margin of the Absaroka Range is probably not represented as a whole by any of the v/ell-known breccia subdivisions of Yellowstone Fark and the northern part of the Absaroka Range. <...>