This photo below shows layers of Quaternary sediment over sandstone bedrock (St. Peter Sandstone) at Wedron Quarry. The Quaternary sediments represent three glacial sequences of the last glaciation and include proglacial river and lake sediments intertongued with diamicton units (tills and ice-marginal sediments). The latter are classified in the Wedron Group, which is named for Wedron Quarry where these till units are well exposed in pits above the sandstone. Photo by A.K. Hansel.