Geology Along the Lewis & Clark Trail

Geologic Points of Interest

Three Forks–Logan Type Sections

Three Forks represents the end of the Missouri River. It is here that the Gallatin, Madison, and Jefferson Rivers converge to make up the Missouri River. At Logan, on the Gallatin River, Peale, in 1898, identified and named the Devonian Three Forks Formation and the Mississippian Madison Formation (now group). Scientists from the Section of Invertebrate Paleontology have been making collections from this outcrop for more than a century. (Lewis and Clark, 7/25/1805, Clark, 7/13/1806)

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