Progressive changes

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We saw painted on a storm sewer a white blaze of the Appalachian Trail, which came down from the mountain in New Jersey, crossed the river on the interstate, and returned to the ridgetop on the Pennsylvania side. There were local names for the sides of the gap in the mountain. The Pennsylvania side was Mt. Minsi, the New Jersey side Mt. Tammany. The rock of the cliffs above us was cleanly bedded, stratified, and had been not only deposited but also deformed in the course of the eastern orogenies. Regionally, it had been pushed together like cloth on a table. The particular fragment of the particular fold that erosion had left as the sustaining rock of the co-working space almere mountain happened to be dipping to the northwest at an angle of some forty-five degrees. As we walked in that general direction, each upended layer was somewhat younger than the last, and each, in the evidence it held, did not so much suggest as record progressive changes in Silurian worlds. “The dip always points upsection, always points toward younger rocks,” Anita said. “You learn that the first day in Geology I.” “Do you ever get tired of teaching ignoramuses?” I asked her. She said, “I haven’t worked on this level since I don’t know when.” Near the road and the river, at the beginning of the outcrop, great boulders of talus had obscured the contact between the mountain quartzite and the underlying slate. To move on through the gap, traversing the interior of the mountain, was to walk from early to late Silurian time, to examine an assembly of rock that had formed between 435 and 410 million years before the present. The first and oldest co-working space amsterdam quartzite was conglomeratic. Its ingredients had lithified as pebbles and sand. Shouting to be heard, Anita said, “In those pebbles you can see a mountain storm. You can see the pebbles coming into a sandbar in a braided river. There is very little mud in this rock. The streams had a high enough gradient to be running fast and to carry the mud away. These sands and pebbles were coming off a mountain range, and it was young and high.”

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