Middle Devonian (Givetian) Silica Formation of Northwest Ohio - Description and Road Log

Abstract

Middle Devonian marine strata are examined in this field trip to the former Medusa South-South Quarry (now the property of the France Stone Company) at the famous Silica locality of Lucas County in northwest Ohio. The formations exposed are the Dundee Limestone, Silica Formation, and Ten Mile Creek Dolomite. Lithologies and profuse fossil content of the Silica Formation suggest an open marine depositional setting contiguous with seas in Ontario and New York. Biostratigraphy indicates correlation of the Silica Formation with part of the Hamilton Group of New York, Pennsylvania, and West Virginia; with the Plum Brook Shale of north-central Ohio; with the Bell Shale of Michigan; and, with the Hungry Hollow Formation of southwestern Ontario.