Huge boulders on the bottom, which the Green would have turned over only once or twice, here were rolled along, when they started, for many yards sensible to not the eye but to the ear.

This was a distinct feature of Cataract Canyon and shows the declivity to be very great and the boulders to be well worn.

The declivity for a few miles is greater than in Lodore, perhaps the greatest on the river.

Sometimes in Cataract the rumble of these boulders was mistaken for distant thunder.

At one rapid I remember that a rock many feet square was swaying from the current.