RI-02 Geology of Clay Deposits Red Wing Area, Goodhue and Wabasha Counties, Minnesota

Abstract

Clay deposits that have been used in the ceramic industry occur sporadically over an area of about 50 square miles in eastern Goodhue County, southeastern Minnesota. The deposits are in the Ostrander Member of the Cretaceous Windrow Formation and to a lesser extent in Pleistocene lake deposits. Currently they are being used in the manufacture of vitreous drain pipe and related products. The Windrow Formation in the area overlies gently folded Cambrian and Ordovician strata. It consists of a lower Iron Hill Member, a ferruginous weathered residuum, and an upper Ostrander Member, a clastic unit. The Iron Hill Member was developed on a mature topographic surface; it formed through residual accumulation of limonite, clay, and chert, the relatively insoluble weathering products of the underlying carbonate rocks. The Ostrander Member formed as floodplain deposits, which were derived from a mixed Precambrian and Paleozoic source. The clay deposits in the Ostrander Member are lenses or tabular bodies as much as a few feet thick and several tens of acres in areal extent that are intercalated with ferruginous sands. The only l known deposit of Pleistocene age is laminated and is as much as 30 feet thick. It is interpreted to have been formed in a glacial lake.