Steamboat Rock

by Cedonia Williams

Steamboat Rock is located twelve miles west of Grand Coulee Dam. It was made by lava flows 20 million years ago. Then twenty thousand years ago, the north side of Steamboat Rock was knocked off by the great flash flood from glacial Lake Missoula. Many floods split around Steamboat Rock because the base is granite and harder to erode than the basalt rock of the lava flows.back to menu