The Adel Mountains Volcanic Field (also known as the Adel Mountains, Adel Volcanics, and Adel Mountain Volcanics) is an ancient volcanic field of heavily eroded 75-million-year-old[1][2][3] igneous rocks about 40 miles long and 20 miles wide (800 square miles, or 2,071 square kilometers)[1][4][5] in west-central Montana about 30 miles southwest of the city of Great Falls. The area was named by geologist John Bartholomew Lyons,[6] who first described the general geology of the region in 1944.[7] The Adel Mountains Volcanic Field is a significant and abundant source of shonkinite, a very uncommon type of intrusive igneous rock found primarily in Montana, Ontario, and Timor.[1][2][8][9] Because of its geologic structure, the Adel Mountains Volcanic Field has drawn the attention of geologists for more than 100 years.[10]
- ^ a b c Merrill-Maker, Andrea. Montana Almanac. 2d ed. Guilford, Conn.: Globe Pequot, 2005. ISBN 0-7627-3655-0
- ^ a b Gunderson, Jay A. and Sheriff, Steven D. "A New Late Cretaceous Paleomagnetic Pole from the Adel Mountains, West Central Montana." Journal of Geophysical Research. 96:B1 (January 10, 1991).
- ^ Harlan, Stephen S.; Geissman, John W.; Snee, Lawrence W.; and Reynolds, Richard L. "Late Cretaceous Remagnetization of Proterozoic Mafic Dikes, Southern Highland Mountains, Southwestern Montana: A Paleomagnetic and 40Ar/39Ar Study." Geological Society of America Bulletin. 108:6 (June 1996).
- ^ "Cliffs High and Steep" - The Adel Mountain Volcanics. Montana Department of Transportation. No date. Accessed 2009-09-30.
- ^ Sheriff, Steven D. and Gunderson, Jay A. "Age of the Adel Mountain Volcanic Field, West-Central Montana." Isochron/West: A Bulletin of Isotopic Geochronology. December 1990.
- ^ Lyons, J.B. "Igneous Rocks of the Northern Big Belt Range, Montana." Geological Society of American Bulletin. 55:4 (April 1944).
- ^ Beall, Joseph J. "Pseudo-Rhythmic Layering in the Square Butte Alkali-Gabbro Laccolith." American Mineralogist. 57:7-8 (July–August 1972).
- ^ Roberts, Eric M. and Hendrix, Marc S. "Taphonomy of a Petrified Forest in the Two Medicine Formation (Campanian), Northwest Montana: Implications for Palinspastic Restoration of the Boulder Batholith and Elkhorn Mountains Volcanics." Palaios. 15:5 (October 2000).
- ^ Hyndman, Donald W., and Alt, David. "Radial Dikes, Laccoliths and Gelatin Models." Journal of Geology. (1987).
- ^ Hearn, Jr., B. Carter. "The Homestead Kimberlite, Central Montana, USA: Mineralogy, Xenocrysts, and Upper-Mantle Xenoliths." In 8th International Kimberlite Conference: The J. Barry Hawthorn Volume. Vol. 2. T. Stachel, ed. Maryland Heights, Mo.: Gulf Professional Publishing, 2004. ISBN 0-444-51777-4