The floodplains

Gerelateerde afbeelding

With a microscope, you can see wood and bark, leaves and roots, seed coats and spores in bituminous coal-and even identify the plants they came from. Buried deeper and folded severely under pressure, it becomes anthracite. Anthracite is roughly ninetyfive per cent carbon and is so hard that it fractures conchoidally, like an arrowhead. Anthracite is iridescent, and burns with a clear blue flame. Coal is a record of tectonics. In late Pennsylvanian time, when the third set of mountains came up in the east and shed still another wedge of debris, kneading it into what had gone before, the great pressure, deep burial, and severe folding co-working space amsterdam produced the anthracites of eastern Pennsylvania, the pod-shaped coalfields of the folded-andfaulted mountains, which erosion and isostasy have lifted from the depths. Anthracite seams are often upside down or standing on end. Here in the Allegheny Plateau, burial was reasonably deep but tectonic pressures were minor, and the result is a lesser grade of coal. We stopped and tried to .collect some but had difficulty finding a sample that would not break up in the hand. “This is very flaky, high-ash coal,” Anita said. “People take it anyway. They come out to these roadcuts with buckets and take it home to burn.” We moved on through miles of coal-streaked roadcuts, and topographically to somewhat higher ground, where the coal seams were thicker. “As you go westward and upsection, you get more coal, because the rivers, growing older, became more co-working space eindhoven sluggish,” Anita said. “The floodplains became broader. There was more ponded water. There was more area for vegetation to grow and accumulatelike the lower Mississippi Valley today.” About five miles east of Clearfield, we stopped at a long, high throughcut full of coal. Draglines were working on both sides of the road. We chipped out some samples with rock hammers. The samples had integrity. “This is a hell of a coal,” Anita remarked. “Good commercial coal. To make it, there would have been about three thousand feet of Pennsylvanian stuff on top of it, which has been removed by erosion. Three thousand feet is the amount of overburden that will produce coal of this rank.” Stirred within by all these free B.t.u.s (twelve thousand per pound), I flailed at the cut with my rock hammer and filled a bag with good commercial coal, to take home and bum in my stove. Anita commented that coal dust was blacking my face. I wiped at it with a bandanna, and asked her, “Did I get it all?” She said, “Good enough for government work.” And we headed up the road.

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