Re: How Earth was Made-History Channel tonight

How the Earth was Made: New, HD, "Yosemite," The formation of Yosemite Valley in the Sierra Nevada mountain range in California is explored.

9 p.m. on History Channel tonight (6 Pacific if you can get the east coast feed). They'll look at why the granite comes off the valley's steep sides, among other things.

Link to History Channel

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Vince
why the granite comes off the valley's steep sides

This explains it:

LOL something like that...the big G constant (ignore the rest)

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Vince
LOL something like that...the big G constant (ignore the rest)

Constant?

Very excited about this episode! Geology is what brought me to the Sierra Nevada and I wrote a research paper on this very topic they are discussing....lets hope they are accurate

I watched it and I thought it was well done. No mention of anthropogenic GW in it. It's au natural

I watched it and thought it was terrific. Most of it was familiar but I had not previously seen it explained why Yosemite granite is so much harder than many other locations. The give and go between Muir and the state geologist regarding why the Canyon bottom is squared off was also interesting. Of course, Muir's observation proved correct. Little things often jump out like the fact that the glacial moraine at the lower end of the canyon has numerous types of rocks in it such as one found from the Cathedral Peak area that would have required glacial transport. I thought this repoert was very well done.

So how did the river cut a deep valley through super-hard Yosemite granite in the first place?

The old Merced was pretty steep. Simular to the way it is on the way down 140. A little here, a little there, and you've got a V shaped valley.

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Old Dude

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mrcondron
The old Merced was pretty steep. Simular to the way it is on the way down 140. A little here, a little there, and you've got a V shaped valley.

Down 140 isn't the same rock.

The power of downhill water containing bits of sand and rock cuts quite a groove over millions of years. That made the V shaped valley. Subsequent glaciers hollowed it out into a U shape. "Lake Yosemite", formed by the last glacial moraine, filled in the V with silt to make it a box shaped valley. Then the state drained the lake to provide water for San Francisco.





Edited 1 time(s). Last edit at 12/23/2009 04:53PM by tomdisco.

It was also because there was a massive amount of uplift due to a piece of the lower mantle that fell off thereby buoying up the spine of the Sierra....This much steeper grade allows gravity to work much more to the waters advantage with erosion...

I would agree this special really was pretty well done....It went much deeper into the Geology than any documentary I have watched thus far on Yosemite/Sierra Nevada...

Watched this show a couple of times now...
It's true you just don't see the glacial polish on the canyon walls like places
such as Grand Canyon Tuol, HH, or Cherry Creek Canyon to name a few.
However, this sure looks like it...

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Oops... guess I should have said that that is Washington Column.

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