One of the few rapids Powell had to run becuase the sides of the canyon are so tall. It is also in the Vishnu Schist - hard rock. The rapids are a 5-7 on the Grand Canyon Scale. III to IV- on the international scale. They ran the rapids on Aug. 14, 1869.
The following is a list of major rapids and other notable features on the Colorado River through Marble Canyon and Grand Canyon below Glen Canyon Dam, in order of their position downstream of Lee's Ferry. Ratings are given for how difficult the rapid is to navigate by whitewater raft or other water craft. The Grand Canyon section of the Colorado River, like several other big-water Western rivers, uses a scale of 1-10 for rapids, 10 being the most difficult. (The Class I-VI classification of rapids is more common elsewhere in the US and internationally.)