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Owyhee
Plateau Bruneau-Jarbidge Eruptive Center Twin Falls & Picabo Volcanic Fields Heise Eruptive Center Yellowstone Volcanic Plateau Current Location of the Hot Spot |
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| Click on the map to learn more about the Yellowstone Hot Spot across the Snake River Plain. |
The Snake River drains southwestward, fed by drainage off the Yellowstone Plateau, located above the Yellowstone-Snake River.
Through the last 12 million years, a dome-shaped topographic high moved northeastward ahead of the hot spot. This elevated bulge was inflated by hot-spot derived thermal energy. As the highland moved northeastward, drainage flowed radially away from it, mainly to the south, north, and east. As the bulge subsided, the west-flowing Snake River captured drainages like the Portneuf and Big Lost Rivers, and the Snake River Plain formed. The movement of the bulge also caused the continental divide to migrate eastward.
The western Snake River Plain is a north - northwest - trending 10 million year old basin bounded by normal faults. It is filled with thick sequences of basalt lava, sediments of Lake Idaho, and stream deposits derived from the Idaho batholith to the north and the Owyhee Mountains to the south. Both arms of the Plain appear to have been strongly shaped by extension of the crust on the North American Plate during the past 17 million years.
