Bass to Randy's Rock, Blacktail Canyon, Oct 17

In Blacktail Canyon, where there is a very visible contact between the Precambrian Vishnu Schist and the Cambrian Tapeats Sandstone. It must have been a high energy contact between the older rock and the advancing sandstone as a sea moved farther and farther. Large pebbles were broken off and remain there today, having been covered over before they had a chance to round off. These seashore pebbles are in several specific layers, as seen below.

Blacktail Canyon is on the north side of the river at mile 120. It's a wonderful little canyon very near the river. Among other things, it's just at the level where the Precambrian Vishnu Schist contacts the Tapeats Sandstone. The contact is near eye level and can't be missed. We camped here in 1997 and made a stop in 2006.

Our camp at Randy's Rock. That rock is just out of sight downstream. It's a large mass of rock in the river with several logs stranded on top. We would guess that someone named Randy had an unhappy experience upon that rock.

Note that the flatter rocks tend to be tilted downstream. This is typical of rocks along rivers. Future geologists, if they see just these rocks, will know which way the river flowed.