Geology and zinc-lead deposits in the Catfish Creek area, Dubuque County, Iowa

A detailed geologic study was begun in 1951 by the U.S. Geological Survey in cooperation with the Iowa Geological Survey to appraise the potentialities of the Iowa part of the Wisconsin-Illinois-Iowa zinc-lead district for (1) zinc ore in rock strata that contain pitch-and-flat zinc ore bodies elsewhere in the mining district and (2) joint-controlled lead and zinc ore like that mined extensively during the 19th century in Dubuque County, Iowa.  This investigation is an outgrowth of a geologic study of the entire district, begun in 1942 by the U.S. Geological Survey.