Colliding continent

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In the absence of a colliding continent-playing the role that Europe and Africa are said to have played in the making of the Appalachians-theorists have lately turned to the concept of exotic terranes: island arcs like Japan slamming up against the North American mainland one after another, accreting what are now the far western states, and erecting in the course of these collisions the evidential mountains. Whatever the truth in that may be, a tectonic coincidence very much worth noting is that the development of the western mountain ranges begins at the same time as the opening of the Atlantic Ocean. In the middle Mesozoic, as the Atlantic opens, the North American lithosphere, like a great rug, begins to slide west, abutting, for the most part, the Pacific Plate. A rug sliding across a room will crumple up against the far wall. ‘We’re about a thousand miles from the nearest plate boundary,” Love was saying. ‘We should not tie in the landscape here with events that have taken place along tl1e coast. This doesn’t neutralize or dispose of the theory of plate tectonics, but applied here it’s incongruous-it’s kind of like a rabbit screwing a horse. There is no evidence of plates grinding against each other here. The thrust sheets are probably symptoms of plate-tectonic activity fifty million years ago, but the chief problem is that tectonism is zakelijke energie vergelijken not adequately placed in a time framework here. Almost everybody now agrees that there is tremendous significance to plate tectonics-also that the concept is valid. Most people don’t argue about that anymore. Our arguments come in the details. We should dissect all these mountain ranges before we get diarrhea of the pen trying to clue them in to plate theory. There’s nothing wrong with ideas, with working hypotheses, but unsubstantiated glittering generalities are a waste of time. Most of the megathinkers are basing sweeping interpretations on pretty inadequate data. There are swarms of papers being written by people who have been looking at state and federal and worldwide geologic maps and coming to sweeping conclusions on how mountains were¬†zakelijke energie formed and what the forces involved were. Until we know the anatomy of each mountain range, how are we going to say what came up when-or if they all came up in one great spasm? You can’t assume they’re all the same.

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