Geologic History of Idaho
Precambrian I
2.5 billion year old xenoliths at Craters of the Moon
2.0 billion year old zircons in Mesozoic batholith
Precambrian II: Belt Sedimentary Rocks
1400 to 800 million years
Thick succession of shallow-water sedimentary rocks
Intracontinental sea? Rift margin?
Paleozoic: passive margin
Island arcs offshore at 200 million years
Arcs dock at 120 million years
Western Idaho suture zone
Subduction zone changes polarity and shifts to central Oregon
Idaho Batholith: 90 to 70 million years
Accompanied by thrust faulting
Followed by up to 30 km of uplift
Cenozoic Extension: 50 million years to today
Challis volcanic field
Columbia River Basalts: 15 million years
Snake River Plain: Yellowstone Hotspot
Ice age (20,000 years ago): glaciers, giant floods, deposition of loess