Map courtesy of Mountain Press Publishing of Missoula, Montana
This weeks picture is a map that has been borrowed from Northwest Exposures, a book about the geologic past of the Northwest. The following paragraphs are excerpts from Roadside Geology of Montana. Both books were written by David Alt and Donald W. Hyndman.
It didn't make sense. . .
A Hand-Me-Down Valley . . .
The grossly oversized valley of Big Sandy Creek south of Havre is probably part of the abandoned segment of the Missouri River, now filled with glacial sediments. These sediments are the gravels, etc. that were brought here by the glacier and then transported again by water from the melting ice as the ice age came to a close. Another segment of the abandoned valley lies just north of Havre, and is also partly filled with glacial sediments.
Terms: bedrock, stream channel
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Earth Science Teacher at Helena High School