Strikes and dips

Gerelateerde afbeelding

From lookoffs in and around Jackson Hole, the view to the north concluded with a high and essentially level tree-covered terrain that seemed to be advancing from the direction of Yellowstone, as indeed it had done, spreading southward, concealing the earlier topography, filling every creek bed, pond, and gulch. When he first rode in that terrain, he saw with no surprise that the rock was rhyolite, which has the same chemistry as granite but not its crystalline texture, because rhyolite cools quickly as a result of coming out upon the surface of the earth. This rhyolite, in a fiery cloud rolling down from Yellowstone, had buried the north end of the Teton Range, where it split and flowed along both sides. From  zakelijke energie vergelijken one end to the other of the valley were outcrops that from a distance looked like snow. Close up, they were white limestone, white shale, and white ash. After noting strikes and dips, and compiling the data, he calculated the thickness of the deposit as approximating six thousand feet. Top to bottom, it was full of freshwater clams and snails, and some beavers, aquatic mice, and other creatures that live in shallows. So the valley had been filled with a lake. The lake was always shallow. Yet its accumulated sediments were more than a mile thick. There was no rational explanationunless the floor of the valley was steadily sinking throughout the life of the lake. Volcanic rocks around the valley were white, brown, red, purple, and numerous hues of yellow and green. Quartzite bouldersstream-rounded, and scattered far and wide-had come from a source far to the northwest, in Idaho, and could not have been transported by ice. In the Mt. Leidy Highlands and along the eastern edge of Jackson Hole he saw other zakelijke energie boulders, larger than human heads. Like the quartzites, they asked questions that, for the time being, he could not answer. He found black and gray sediments of the Cretaceous seas.

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