The best general date

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In earth history, that was not long ago. He said the best general date for it was ten million years-when the central Rocky Mountains, which had long since taken form as we know them, were bur-‘ ied up to their chins. Only the highest peaks remained uncovered, like nunataks protruding through continental ice, or scattered islands in a sea. The summits of the Wind River Range were hills above that Miocene plain. The highest of the Bighorns stuck out, too-as did the crests of other ranges. Forty million years before that, in Eocene time, most parts of the Rocky Mountains seem to have looked much as zakelijke energie vergelijken they do today, and so did the broad basins among them. The region as a whole was closer to sea level, but its relief was essentially the same. It was a bizarre story, full of odd detail. Limestone, for example, is ordinarily a marine rock, derived from corals and shells. What so1t of limestone would form on a surface that came sloping down like a tent roof from the ridgelines of buried mountains? The surface had been laced with streams, Love said, and in the rumpled topography east of the buried ranges the streams filled countless lakes. Old carbonates dissolved and were carried by the streams to the lakes. Lime also leached out of the granite in the mountain core. Freshwater limestones formed in the lakes, self-certified by the fossils of freshwater snails. There were other fossils as well-discovered in dense compilations in confined areas that have been described as concentration camps and fossil graveyards. They suggest a modem plain in south-central Brazil where heavy seasonal rains so elevate the waters of innumerable lakes that animals crowd up on small islands and perish. Limestone, being soluble in water, formsĀ zakelijke energie fertile valleys in eastern North America but in the dry West remains largely undissolved. Its inherent ruggedness holds it high, while weaker rock around it falls away. Limestone is the protective caprock of Pine Bluffs. Junipers were flourishing in it, as were ponderosa pines and Spanish bayonets.

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