CLICK ON PICTURES TO ENLARGEYesterday, we drove to Gillette, Wyo. to help celebrate my wife's aunt's 90th birthday. On the way home as we went by Sundance mountain, I started wondering how all of that looked from the top... you know, Devils Tower, Sundance Mountain... the whole area. So this morning I was looking at Sundance on Google Earth and noticed this almost perfectly circular formation just east and a little north of the Sundance mountain. (Upper right in this screen shot.) Anybody know anything about it? Does it have a name? Is it an "intrusion," a volcano? A really, really big fossilized buffalo chip? Or what?
10 comments:
I keep noticing a boring formation just east of the first topic on Decorum Forum. Sabato something or other.
Right. That Sabato thing's getting old, huh Bob? Don't worry, I'll discuss it in good time. Meanwhile, It's not nearly as old as the "Round Mountain" formation by Sundance. I now have the complete scoop on it from a guy (geologist) who has actually surveyed it. (I'll do post on him too, as soon as I get the necessary permissions.) Suffice it for now to say that Bob Ellis and the 6,000 year old earth people ain't gonna like his answer. That thing is 40 or 50 million years old.
It looks like a similar formation to Inyan Kara, doesn't it? Even more intriguing to me than knowing what it is is knowing why I never noticed it, even having driven past it hundreds of times in my life...
Yeah, Aaron, Inyan Kara is just south of it. And not nearly as perfectly circular.
Butch says it looks pretty symmetrical at ground level too, Aaron. But yeah, like you, I've never noticed it before either.
I'll ask Uncle Joe. He used to be a geology teacher, so I think he'll know what it is.
Cool, Aaron. We'll compare answers with Butch. I really do hope Bob Ellis checks in too. That should be a hoot.
The topography of this feature is quite fetching, as well.
From Wikipedia'
"Green Mountain hogbacks
Green Mountain (Google Maps), also known as the Little Sundance Dome, is found just east of Sundance, Wyoming. It is a circular dome about 1800m across and 1400m wide surrounded by a rim of triangluar hogbacks (similar in appearance to flatirons). Green Mountain itself, much like the Black Hills, is a laccolith formed by the intrusion of magma into the Earth's crust (Cleland, 354-355). The hogbacks surrounding the mountain are steep (with dip slopes of approximately 50°) and point upward towards the center of the mountain."
The Black Hills are a giant version of Green Mountain. If you wish it, you can drive on to the old railroad right of way above the rodeo grounds in Deadwood and pick up pre-Cambrian rocks that are, perhaps, the second oldest on the surface of the planet. Geologically speaking, this is a happening place. Well it was, 6000 years ago....
Thanks, OneGuy. Have you noticed this formation before? I'm struck by its beautiful symmetry. The more I look at it the more I see. It has a delicate, mandala like quality. And it's over a mile wide.
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