Friday, December 11, 2015

Geo-challenge: hiking on (not in) a river valley

Where on Google Earth are we?
Some hints ...

Arrows point to stream deposits from roughly 20 million years ago. Obsolete names date from the late 1800s.

Stream deposits cap a ridge (inverted topography); Devils Smoke House and Gabriels Castle behind. Note spectacular unconformity.

The trail on the ridge crest passes through stream deposits turned to rock and photogenically eroded. 
Layers of sand, pebbles, cobbles record changes from about 20 million years ago.
Cemented layer, above siltstone nodules in fine matrix, above unconformity; cross-bedding near top of photo. 
Mostly siltstone nodules.
Crystalline clasts from the Rocky Mountains.

I found many puzzling weathered forms in cemented sand. Here are a few:
Happy dog for scale.

Recognize this place? Please contribute via a Comment. If the answer isn't in the Comments below, check back in a week or so.


  1. No, I don't recognize the place, but it looks fascinating. So, you don't have any snow yet, either? El Nino is making it feel like springtime around here. I can't believe Christmas is less than two weeks away! Happy Holidays!

    1. Happy Holidays to you too, PP. This was a tough one, answer below.

  2. I have no idea where this is. Somewhere in central Wyoming, perhaps?

    1. Nina, this was harder than I thought it would be. Answer below.

  3. Tough challenge apparently, only one person came close (mike n). It's Pawnee Buttes area in northeast Colorado. More to follow.