Rising from the Plains

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In the middle Precambrian, not long after the end of the Archean Eon, lava ran down the sides of big volcanoes and far out onto a seafloor that is now a part of Wyoming. It is impossible to say where the volcanoes stood, but the fact that they existed is stated by the lava. Somewhat later, the lava was folded and faulted, apparently in the making of mountains. Still more Precambrian ranges, of vast dimension, came up in the region, and shed twenty-five thousand feet of sediment into seas that covered parts of Wyoming. After the sediment formed into rock, even more episodes of mountain building heated and changed the rock: the limestone to marble, the sandstone to quartzite, the zakelijke energie vergelijken shale to slate. Meanwhile, coming into the crust at depths on the order of six miles were vast bodies of fiery-hot magma, much of which happened to have the chemistry of granite. Under eastern Wyoming, where Interstate 80 now cro5ses the Laramie Range, the magma contained enough iron to tint the feldspar and make the granite pink. It is axiomatic that big crystals grow slowly. Slowly, the magma cooled, forming quartz and feldspar crystals of exceptional size. All of that occurred in Precambrian time-during the first eighty-eight per cent of the history of the world. Often, Precambrian rock is collectively mentioned as “the basement” -the basement of continents-as if that is all there is to say about it before setting up on top of it the wonders of the world. This scientific metaphor is at best ambiguous-connoting, as it does, in one sense a firm foundation, in another an obscure cellar. In either case, it dismisses four billion years. It attempts to compress the uncompressible. It foreshortens a regional history wherein numerous zakelijke energie ancestral mountain ranges developed and were annihilated-where a minor string of Pennsylvanian ridges could scarcely be said to represent the incunabular genealogy of the Rockies. In late Cretaceous and early Tertiary time, mountains began to rise beneath the wide seas and marsh flats of Wyoming. The seawater drained away to the Gulf of Mexico, to the Arctic Ocean. And, in David Love’s summary description, “all hell broke loose.” In westernmost Wyoming, detached crustal sheets came planing eastward -rode fifty, sixty, and seventy-five miles over younger rock-and piled up like shingles, one overlapping another. In the four hundred miles east of these overthrust mountains, other mountains began to appear, and in a very different way.

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