Central Montana Geology

by David Baker

Central Montana contains a "showcase" of geologic features, some of which are "world-class" in character. I conducted a series of 7 geology field trips/workshops in the spring and summer of 1999 covering many of these features. The workshops were specifically designed for teachers and the general public so that they can identify major geologic features in the area and the plate tectonic motions that caused them. Plate tectonics revolutionized the earth sciences 35 years ago and it is now time to bring local examples into the classroom and into public awareness.

Highlights from these field trips include the large waterfalls on the Missouri River, a 450 foot deep pre-glacial gorge on the south side of Great Falls, a large lake dammed by a continental glacier and its outlet at Shonkin Sag, thrust sheets stacked like shingles, magmas from depths exceeding 100 miles, diatremes, and the type-locality for shonkinite. The Square Butte shown in the image on the right is located between Geraldine and Stanford. Geologists come from many parts of the world to see the shonkinite and learn why it has so much potassium.

An eighth field trip/seminar/workshop focused on the precious gemstones and precious metals found in Montana. It provided an in-depth coverage of these unusual deposits. Montana is the only state in the U.S. with producing mines for sapphire, platinum and palladium.

An extensive guidebook was prepared for each field trip.

Contents

Regional Stratigraphy Field Trip

Caves and Karst Field Trip

Water Flows Underground from Central Montana to Manitoba

Rocky Mountain Front Field Trip

White Cliffs of the Missouri Field Trip

Shonkin Sag and Square Butte Field Trip

Little Belt Mountains Field Trip

Great Falls Area Field Trip

Precious Gemstones and Precious Metals Field Trip/Seminar/Workshop

Plate Tectonics of Montana and the Northern Rockies

Professional Information for David W. Baker

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