Contour map of the bedrock surface, Branford Quadrangle, Connecticut
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Geology topics
Publications and source records attributed to C. Erwin Brown.
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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.
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Geologic investigations were begun in Iowa to appraise; (1) the possible occurrence of zinc ore in strata that elsewhere in the Upper Mississippi Valley zinc-lead district have been the principal sites of zinc concentration; and (2) lead ore of the type known as "crevice deposits," which were mined so extensively during the 19th century in Dubuque County, Iowa, but have been mined very little since 1910.
Geologic investigations were begun in the Iowa portion of the Wisconsin-Illinois-Iowa zinc-lead district to appraise its potentialities: (1) for zinc ore in strata that elsewhere in the mining district contain large zinc ore bodies and (2) for lead and zinc deposits of the type that were mined extensively in Dubuque County, Iowa, during the 19th century.