The Gulf of Mexico

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The Gulf of Mexico was a good example of a geosyncline, with a large part of the Rocky Mountains sitting in it as more than twenty-five thousand feet of silt, sand, and mud, siltstone, sandstone, and shale. “The South will rise again!” Deffeyes used to say. The huge body of sediment would one day be lifted far above sea level and dissected by weather and wrinkled into mountains in the way that the skin of an apple wrinkles as the apple grows old and dry. The steady rhythm of these orogenies was known as “the symphony of the earth”-the Avalonian Orogeny in latest Precambrian time, the flexplek huren haarlem Taconic Orogeny in late Ordovician time, the Acadian Orogeny in late Devonian time, the Antler Orogeny in Mississippian time, the Alleghenian Orogeny in Pennsylvanian-Permian time, the Laramide Orogeny in Cretaceous-Tertiary time. It was a slow march of global uplifting effects-predictableproceeding through history in stately order. By the end of the nineteen-sixties, the symphony had come to the last groove, and was up in the attic with the old Aeolian. Mountain building had become a story of random collisions, unpredictable, whims of the motions of the plates, which, when continents collided or trenches otherwise jammed, could give up going one way and move in another. The Avalonian, Taconic, Acadian, and Alleghenian orogenies were now seen, in plate theory, not as distinct events but as successive parts of the same event, which involved the closing of an ocean called Iapetus that existed more or less where the Atlantic is today. The continents on either side of Iapetus came together not head-on but like scissors closing from the north, folding and faulting their conjoining boundaries to make the Atlas Mountains and the Appalachian chain. It was a Paleozoic story, and flexplek huren breda tl1e motions finally stopped. In the Mesozoic, an entirely new dynamic developed and the crust in the same region began to pull apart, to break into blocks tlrnt formed a new province, a Eurafrican-American basin and range. The blocks kept on separating until a new plate boundary formed, and eventually a new marine basin, which looked for a while like the Red Sea before widening to become an ocean.

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