U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
Areas of Critical Environmental Concern
|Bruneau Field Office|
The Big Picture
Extending across southwestern Idaho between the Owyhee Mountains and the Boise Front is the broad valley of the western Snake River Plain, which evidence indicates began as a continental rift about 12 million years ago. The earth's crust began to be pulled apart, northeast to southwest, stretched thin like taffy. The Owyhee Mountains and the Boise Front rose along faults bordering the rift, reaching their present heights between 9 and 11 million years ago.