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slgwv

slgwv club

Posted: 15 Feb 2009

Taken: 01 Nov 1980

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Silver Surfers Silver Surfers

Nevada Nevada

Geology Geology

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reservoir •
Virgin Canyon •
Clark County •
faulting •
faults •
Lake Mead •
Colorado River •
Nevada •
Arizona •
USA •
geology •
fault scarp •

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Fault Scarps in Virgin Canyon

Fault Scarps in Virgin Canyon
Lake Mead, USA, looking toward the Nevada side. As the reservoir filled, here and there the slopes of the surrounding canyon failed as they got soaked. I don't know the timescale offhand--I suspect they're still slowly sliding, but that most of the motion happened soon after the ground first got saturated. It's an example of geologic consequences from human activity! ;) Btw, with the current drought the lake in this area has pretty much returned to the original river channel.
Comments
 tiabunna
tiabunna club
That's fascinating. Not long ago there was a major land slip into a dam with huge damage, is the speed of the land slippage a function of the rock type?
10 years ago.
 slgwv
slgwv club
It's certainly a major factor. Rock types containing minerals that swell as they absorb water are particularly bad news--that was probably a major reason for the collapse of St. Francis Dam in southern California in 1928, an almost forgotten man-made disaster now.
Here we're dealing with highly fractured metamorphic rocks, and I suspect what's happened is that the water has lubricated fractures that are oriented so they can slide under gravity.
And this pic was deemed inappropriate for a group about human-caused alterations to landscapes--go figure!
10 years ago.

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