Mile 77-118 - Upper Granite Gorge

River runners enter the Upper Granite Gorge immediately below Hance Rapid. The “gorge” is defined by the basement layers of Grand Canyon, igneous and metamorphic rocks that have been bent, twisted, and thrust upwards during mountain building events. In the gorge the river has exposed 1.7 billion year old Zoroaster Granite and Vishnu Schist. Because the rock in the gorge does not easily erode, the river becomes swifter and the rapids grow larger. The Upper Granite Gorge is considered to be 41 miles long, spanning from below Hance Rapid to Elves Chasm.