The north and east

Gerelateerde afbeelding

New volcanoes rise to the north and east. Fissures spread open. Materials ranging from viscous lavas to flying ash obliterate tl1e existing topography. Streams disintegrate these materials and rearrange them in layers a few miles away. So far, these scenes-each one of which is preserved in the rock of Jackson Hole-have advanced to a point that is 99.8 per cent of the way through the history of the earth, yet nothing is in sight that even vaguely resembles the Tetons. The Precambrian rock remains buried under younger sediments. At the surface is a country of undramatic hills. The movements that brought the Overthrust Belt to western Wyoming-and caused the more easterly ranges to leap up out of the ground-have all been compressional: crust driven against crust, folded, faulted, and otherwise deformed. Now the crust extends, the earth stretches, the land pulls apart-and one result is a north-south-trending normal fault, fifty miles long. On the two sides of this fault, blocks of country swing on zakelijke energie vergelijken distant hinges like a facing pair of trapdoors-one rising, one sagging. The rising side is the rock of the nascent Tetons, carrying upward on its back the stratified deposits of half a billion years. One after another, erosion shucks them off Even more rapidly, the east side falls-into a growing void. Magma, in motion below, is continually being drawn toward volcanoes, vents, and fissures to the north. Just as magma moving under Idaho is causing land to collapse and form the Snake River Plain, magma drawn north from this place is increasing the vacuity of Jackson Hole. As the magma reaches Yellowstone, it rises to the surface, spreads out in all directions, and in a fiery cloud rolls down from Yellowstone to bury the north end of the Tetons, where it splits and flows along both sides. The descending zakelijke energie valley floor breaks into blocks, like ice cubes in a bucket of water. Some of them stick up as buttes. A lake now fills the valley-shallow, forty miles long-and in it forms a limestone so white it looks like snow.