An extensive early proterozoic glaciation in North America?

Abstract

The Early Proterozoic Gowganda Formation of Ontario has long been considered to be a glacial. Similar deposits of similar age occur in the Northern Peninsula of Michigan, at Fern Creek and on the north side of the Dead River Storage Basin, in the Medicine Bow Mountains of Wyoming and at Chibougamau in northern Quebec. The wide separation of these areas indicates as extensive glaciation in Early Proterozoic times. The chemical composition of tillite matrix materials and laminated argillites from most of these areas shows a remarkable homogeneity which may reflect the homogeneous nature of a large part of the Superior craton.