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发表于 2010-5-23 20:55
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[Homework]2010-05-23 黄石公园-3
On liuxiaojun686
Rocks below ground heat the water under pressure for around 90 minutes. Suddenly, some water spurts through a tiny 5-inch wide crack in the rocks. This causes a drop in the pressure within the water chamber. In an instant, thousands of gallons of water are turned to steam and blasted up into the air.
When the pressure builds up enough, steam bubbles start rising to the surface, the system depressurizes, then the follow eruption can occur.
Old Faithful shows that rocks below the surface are very hot. Scientists find clues to a violent path 34 miles southeast of the hot springs, on the shores of a circular lake called Indian ponds.
So, a field geologist, my job is to basically be a rock detective, and so I tried to determine what the origin is and what the history is of that particular rock. There we go, Ok, now, in this particular case,Let's look at this, this rock, when it started, it was just a loose sand, you could just put your fingers through it.
The solid bolder is formed from millions of individual grains of sand. Microscopic analysis reveals the grains have been cemented together by chemicals and pressure deep under the ground. But how did the rock get to the surface? Morgan has chemically dated the rocks and discovered that, 3,000 years ago, the bolder was blasted out of the ground by the hot water explosion of a gigantic geyser.
You would see boiling water, rock fragments and fine muddy material, been ejected up into the air as high as 3 to 5,000 feet, and then at some point, material would start raining down from this explosion column. Now you wouldn’t wanna be standing next to one of those.
Indian pond is the crater that the geysers are left behind.
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