Posted by: Rose | May 1, 2009

Recesses of the Mind

I eddied out below Clavey Falls on the Tuolomne and looked at the rock in front of me. “Boundinage”, I exclaimed!

Where did this come from? Why had I been hiding this term in the recesses of my mind, for it suddenly to leap out when I was least expecting it? My memory appears to have a geology locker that I didn’t know existed.

Boudins on the Tuolumne. No scale, tut tut.

Boudins on the Tuolumne. No scale, tut tut.

Boundins are formed during extension of the rock. In this example the beds of the sediment are orientated vertically and composed of muddy and sandy beds. Because the sandy beds contain more quartz, they are ‘strong’ or ‘competent’. So when they are stretched, these beds break apart and form the sausage shape boudins, whilst the muddier beds can quite happily be elastic (fantastic).

We paddled 18 miles of the Tuolumne and that’s a lot of miles of big bouncy grade III and IV. I can happily say that there was a distinct lack of rocks in the river, just how I like it. We were supposed to overnight on the river, but when the shuttle took 3 hours (miles of switch-back dirt tracks and LA stylee ghetto bridges – don’t ask), we didn’t manage to get on until 6pm. With darkness only around the corner, we paddled the first rapid and got off! It turned out to be a good choice; there were no good camping spots for miles after this…

Much respect and gratitude to Mrs R for the provision of the marshmallows. Heather really knows how to make a perfect camping spot even betterer.

Tony's Rapid, Tuolumne. Photo by Dave Hodgkinson.

Clavey Falls, Tuolumne. Photo by Dave Hodgkinson.

Yours truly on the Tuolumne. Photo by Mark Rainsley.

Yours truly on the Tuolumne. Photo by Mark Rainsley.

Kit carnage at the get off. Don't look too closely at the graffiti!

Kit carnage at the get off. Don't look too closely at the graffiti!

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