Caribou County has the forested mountains of the Idaho-Wyoming thrust belt on its eastern side, and the wide Bear Lake and Gem valleys on its west, part of the Basin and Range province. Pleistocene volcanic rocks, mainly basalts, fill the Blackfoot Lava field and much of Gem Valley to the west. China Hat and China Cap are Pleistocene rhyolite domes. Phosphate mining still controls the economy of Caribou County, with active mines operated by Simplot, FMC, Monsanto, and Agrium between Soda Springs and Afton, Wyoming.
For more information see geology text from Rocks, Rails and Trails. Also see the Fortsch and Link field trip from "Geologic Guidebook to Eastern Idaho".
P.K. Link, 10/02
Rocks Rails and Trails: pages
Introduction to the Geology of South & East Idaho
Introduction to Geologic Diagrams
Geologic cross sections
Relations between Geology, Topography and Drainage Systems in Idaho
Drainage and mountain range map for eastern Idaho
Table of Geologic Events in Southern Idaho
Drainage Systems, Rails and Trails
Geologic Provinces along the Oregon Trail
Rocks of the Eastern Idaho Mountains
Southeast Idaho Phosphate Mining
The Thrust Belt of Southeastern Idaho
Views of Thrust Faults
References on Idaho Geology
Section 3, History of Eastern Idaho
Section 3, Chapter 8 -"Famous Potatoes" Agriculture & Irrigation
Geology of the Soda Springs Area
Section 4, Chapter 11 -Caribou Mountain Area
Section 4, Chapter 12 -Gem Valley & Chesterfield
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