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workmanflock wrote:Collbran was fast, like less than five minutes and killed a couple people. I'm not a geologist but I think its volcanic ash in the underlying clay that makes it so damn slippery when it gets wet out here. I think the base of the Mesa is this stuff https://en.wikipedia.org/wiki/Mancos_Shale which is horrendous when wet. A guy named Rex Cole will eventually release a book detailing the geology of the Mesa and the events that caused the big slide in Collbran.
The Mancos (90 million years old) forms the base of the Grand Valley, up the Gunnison and Uncompahgre rivers through Delta, Paonia, Montrose, etc. However, this is different from the northern side of Grand Mesa. The basal unit on the northern side is the Wasatch Formation (60-50 million years old). Mudstone and shale. On top of that is the Green River Formation (45 million years old). Sediments of the ancient Green River Lake. More mudstone, shale, marlstone. Yes, fine grained sediments and clay = slicker than snot.
Out of curiosity, where'd you do your geology work? I'm a lousy armchair geologist but I've got a few of the books you mentioned and have been toying with the idea of writing a book on the Colorado National Monument.
A guy named Rex Cole will eventually release a book detailing the geology of the Mesa and the events that caused the big slide in Collbran.
That would be an interesting book to read, and maybe I will check out some of the other books referenced in this thread! I took Geology 101 & 102 a 100 years ago, so I might pick-up a plaid shirt and a pocket protector when I get the books, maybe update my glasses to black rim too!
A guy named Rex Cole will eventually release a book detailing the geology of the Mesa and the events that caused the big slide in Collbran.
That would be an interesting book to read, and maybe I will check out some of the other books referenced in this thread! I took Geology 101 & 102 a 100 years ago, so I might pick-up a plaid shirt and a pocket protector when I get the books, maybe update my glasses to black rim too!
