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Yosemite Nature Notes - 9 - Frazil Ice

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[Music]
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We're on Yosemite Creek
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below Lower Yosemite Falls,
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it's a cold early April morning,
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and we're watching the frazil ice formation.
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Frazil ice are these small crystals of frozen mist
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that forms in Upper Yosemite Falls and Lower Yosemite Falls.
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The particles of ice wash down the stream with the liquid water
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in a flurry, a slushy, slurpee, goopy mass
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that in many cases flows like lava.
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So if you can imagine in your mind a giant slurpee machine
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that is putting out millions of gallons of slurpee
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into Yosemite Creek,
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it's amazing;
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it's not snow, it's not ice,
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it's something in the middle
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and to watch it move underneath Yosemite Creek Bridge
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is pretty incredible.
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This is one of the more unique phenomenon
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that you'll see in Yosemite,
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if you're lucky enough to be here in March and April,
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which is the prime season for this,
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but it's an amazing thing
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to watch something this dynamic in Yosemite Creek.
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You see something that the millions of visitors
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who come in the summertime
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never imagine something like this.
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It behaves a little bit like cement in some ways,
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where it stops and it forms kind of a stationary piece
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and then the flowing pieces go past that stationary piece.
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The ice will surge into place
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and with enough thickness it stops
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and the creek will flow a different direction.
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The water will drain out of where it has just deposited it,
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leaving this, what looks like snow,
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but again, it's soft, it's unconsolidated,
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you would plunge right into that.
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Now we see this dynamic change
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as the frazil ice has built up its own levy
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and caused the channel to clog up and it's coming toward us,
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we're going to have to be ready to move here,
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as the Yosemite Creek in all of its might is coming toward us.
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But you'll see this lava flow effect,
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where the ice is going to accumulate
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and build up blockages
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that stop it from coming in a certain direction.
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It's the full force of Yosemite Creek,
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which can be up to say a 100 cubic feet per second,
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when that is moving along in a place where we don't expect it,
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where engineering of building roads and trails and bridges
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