Our Favorite Hot Springs of Idaho
Ninety percent of Idaho's 340 hot springs are the result of leftover energy heating water near fault lines. This energy is essentially leftover from a 17 million-year-old meteorite collision that occurred in present-day southeast Oregon. The collision dramatically altered the once lush, forested environment into the high desert landscape that is familiar today.
The impact of the meteorite was deep, in fact so deep that it remains stationary while the North American tectonic plate shifts above it. As the plate slowly moves, the hot spot periodically erupts volcanic lava - leaving a traceable path of volcanic activity behind.
This path of volcanic activity is not only responsible for Yellowstone, but for almost all of the activity of the hot springs in Idaho. Other evidence the hot spot has left behind include Craters of the Moon and the basalt lava flows visible throughout southeast Idaho, most notably off Interstate 84.
As the earth above the hot spot continues to shift, Yellowstone will eventually look like Craters of the Moon does now. Which means Craters once looked like present-day Yellowstone.
Also worth noting: The meteorite that hit southeast Oregon 17 million years ago had an impact so great that it wiped out all life in the Pacific Northwest; lava blasted out of the impact crater for hundreds of miles and sent a river of lava to the west coast, creating the Columbia Plateau in its wake (Source: Roadside Geology of Idaho, Mountain Press Publishing Company, 1995).