The Derby-Doerun Dolomite is a

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

exposed in southeast

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

. Originally the Derby and Doerun were originally considered separate formations, but now considered a single unit.Thompson, Thomas L., 2001, ''Lexicon of Stratigraphic Nomenclature in Missouri,'' Missouri Department of Natural Resources, Division of Geology and Land Survey, Report of Investigation Number 73, p 83-4
/ref> The combined name is from the Derby Mine and the Doe Run Lead Company of the Old Lead Belt.

References

* Cambrian Missouri Dolomite formations Geography of St. Francois County, Missouri Cambrian System of North America Geologic formations of Missouri {{US-geologic-formation-stub

See also

References