Grand Canyon -- Day 6

September 30 -- Into the Precambrian
After a quick float from camp we eddied and explored the mouth of the Little Colorado which was muddy from the storm that hit northern Arizona a couple of days before we started the trip. In Andy's blog he speculates about the water level, this chart shows that Andy's estimate was just about right:

From Grand Canyon Storm

I clambered around on the bluff between the confluence, a classic shelving outcrop of Tapeats Sandstone, poorly sorted and lots of cross bedding. At point on the bluff there was a large ring and a big bolt to tie off boats, this ring must predate the dam, as it is quite a way above the river. Others played in the mud and watched the mixing of muddy and clear water.

From Grand Canyon Day 6

After the LCR confluence the riffle at Crash canyon was pretty exciting at this water level, the Grabner flipped, Marshall and I made the eddy and tried to help corral swimmers and boat but think that we hindered the self rescue more than we helped. The eddy was very active and unpredictable.
After that we crossed the "Great Unconformity" and the Canyon opened up.

From Grand Canyon Day 6

For the rest of the day we kept company with ruddy rocks of the Dox Sandtone and could see much of the rest of the Unkar Group around us after we crossed the Temple Butte Fault at Carbon Creek.

From Grand Canyon Day 6

Lots of active riffles in this part of the river and sharing the oars with Marshall made for fun rowing. Tanner Rapid was pretty easy and had a great exposure of a fault contact between the Dox Formation and the Cardenas Lava.

From Grand Canyon Day 6

After lunch we took a hike (map form Dan's blog) to some hilltop ruins and an overlook of the Unkar Rapids and Unkar Delta where there are ruins of an Anasazi agricultural settlement.

From Grand Canyon Day 6

At the overlook of Unkar Rapid and later at the gravel bar on the rapid there was much gnashing of teeth, discussing of routes, holes, rocks, and so on. It looked really intimidating without many options for an easy run. This was our first real major rapid since House Rock some of us were a little jittery. The kayakers and one raft took a bony right sneak, while the other three rafts took the center of the main tongue but powering to right...a fairly dry and uneventful run.
That night we camped at Rattlesnake, a nice spot, shelving sandy platforms on Proterozoic sandstone. Tomorrow will be exciting! We'll drop into Granite Gorge, the Archean heart of the canyon, and first day of multiple big rapids. YeeHA!