Friday, April 22, 2011

Falling Rock

About a week ago after several days of warming that followed our huge snow dump of April 7th and 8th, a part of a local outcrop gave way in the middle of the night, with this large rock coming to rest at a roadside pullout.
I stopped to take pictures a day or two later, pulling across the road into another pullout away from the crumbling, cliffy limestone. You can see the hole left by the chunk that fell, a chunk that then broke into small and large pieces. And notice uphill of the exposure where the hole is: it looks like the whole lower mass may have broken loose from the upper mass at some point, perhaps before the road went through, or maybe that's a small, curvilinear fault (see first photo).
The large rock and a few of the smaller chunks, were carefully protected by orange cones and Caution Tape.
The Caution Tape has since been removed, as have many of the smaller chunks, with the large rock still sitting there in reminder of the freeze-thaw action of many years. The pullout no longer looks like a good one to use, as the back half of what remains to one side of the large hole looks unstably fractured and overhung.

A "Falling Rock" sign is posted just past the downed rock for uphill travelers through the canyon; there is no companion sign on the other side of the road for the downhill approach. 'Tis the season for roadside rockfalls, so watch where you park!

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