Here we're coming into the brownish cliff area on Highway 317, which I mentioned in my last post about Meadow Valley Wash - these are the rocks below the dark basalt flows.
They show a columnar fracture pattern...
...and tower over my truck.
I wonder what these rocks are? The short weed-like plants (less than a foot high) are offered for scale - that's all you get for now!
5 comments:
Love the fractures of columnar basalt. Would love to build a house from it someday. Looking forward to more.
Looking at rocks is like looking at wood - one bit should look like another - but never does.
Lucy
We'll get back to these rocks in a few days - but I don't think they are basalt!
Didn't realize we were supposed to guess! I'm thinking an ash flow tuff, intermediate to felsic in composition. The fairly fresh surface where the weathered rind has spalled off in the last picture shows that it's light, but not as light as if were a straight up rhyolite. There's also some weak horizontal bedding, and I think I'm seeing some angular pyroclasts in there.
Yes - the answer is in the next post in this series! :)
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