Geology on the East Side of the Sandias

My girlfriend is taking a geology class and had to travel to the east side of the Sandias to do some strike and dip measurements, as well as do some geologic mapping. I wandered around and took photos of things I thought were neat.

One neat thing along this stretch were the vast number of dikes cutting through the granite. A dike is a place where there is an igneous intrusion along a crack in the rocks. The most obvious one is shown here:

but there were others as well.

The granite itself was interesting, as it was very crumbly. It resembled sandstone but was actually a granite that weathered really easily. It had a large percentage of biotite, which oxidized easily and caused the other constituents to fall out.

There was a few layers of black shale. Apparently, this area was once on the edge of a vast sea, and its depth varied at different times throughout history. I guess that is obvious, seeing as it is on the backside of a mountain, today.

There was a layer of limestone that contained many exposed fossils as well. You can see several shells visible in this photograph.

More evidence of this was a layer of larger rocks wedged in a sandstone. These larger rocks deposited in an area with a higher flow rate (perhaps a river) or wave action.

Thank you for reading my post!

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One Response to Geology on the East Side of the Sandias

  1. Pingback: 9/21/14, 9/22/14: Daily Post | An Engineer in the World

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