At high temperature

Gerelateerde afbeelding

“The sea lilies grew in clear, shallow water a little offshore,” Anita said. “It was a coast like Fiji’s, or the Philippines’, or Guatemala’s. The coral and the thick shells tell you the water was warm. The rock is dark because it is full of dead oil, which came in later-much later. Oil migrated into these rocks and was cooked at high temperature. The conodonts will tell me the temperature.” In the deformed, sedimentary Appalachians, the rock not only had been compressed like a carpet shoved across a floor but in places ┬áhad been squeezed and shoved until the folds tumbled forward into recumbent positions. Some folds had broken. Some entire regions had been picked up and thrust many miles northwest. Dozem of other complexing events had locally co-working space rotterdam affected the structures of the Ridge and Valley Province. One therefore could not know what to expect next. Whole sequences might suddenly be upside down, or repeat themselves, or stand on end reading backwards. Among such rocks, time moves in and out and up and down as well as by. “It’s a real schlemazel,” Anita said. “Not by accident is geology called geology. It’s named for Gaea, the daughter of Chaos.” Among the west-dipping Silurian formations of the Delaware Water Gap, one might project but could not reasonably expect Devonian rock to westward. It would be there if the stratigraphic package was intact and had not been overturned. The rock of that first big Pennsylvania roadcut was early Devonian in age. Leaving it, we moved seven miles west along the interstate and twenty million years up the co-working space utrecht time scale, where we stopped at a roadcut of middle Devonian marine siltstones and shales, so rich in organic residues that it was black as carbon, with corals that had been sliced by dynamite and resembled sections of citrus. Cambrian, Ordovician, Silurian, Devonian-for this crunched and shuffled country we were experiencing remarkable consistency in an upward voyage through time. And now in the silken muds of these Devonian seafloors we were seeing the final stages in the long tranquil interval between the Taconic and Acadian revolutions.

Geef een reactie

Het e-mailadres wordt niet gepubliceerd. Verplichte velden zijn gemarkeerd met *