Shallow or deep

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The conodont types differed as a result of water temperatures, not as a result of their geographic origins. Shallow or deep, conodonts of northern Europe were the same, because the water was cool at all depths. But here in America, with the equator running through the ocean where San Francisco would someday be, Ordovician water temperatures varied according to depth. Those apparently Scandinavian fossils were forming in deep cool water, the American ones in warm shallows. Moving east from the Toiyabe Range and into Utah, Anita had gone from outcrop to outcrop through the Ordovician world, from ocean deeps to the rising shelf into waist-deep limestone seas. She could see now that the thrusting conference room haarlem involved in the eastern orogenies had shoved the cool-water conodonts and their matrix rock from the deep edge of the continental rise into what would be Pennsylvania. They had travelled, to be sure-but they had more likely come from Asbury Park than from Stockholm. In the thrusting and telescoping of the strata, the transition rocks of the American continent’s eastern slope had been deeply buried. In them, almost surely, would be a mixture of cool-water and warm-water conodont types. To the east of the Toiyabe Range, there had been less telescoping, and the full sequence was traceable-from the cool deep continental edge up the slope to the  conference room breda warm far-reaching platform. “The change had nothing to do with moving plates,” Anita concluded. “Nothing to do with plate tectonics. I blew it. It was an environmental change, an environmental sequence.”

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