Friday, May 27, 2011
The Allegheny Mountains - Geology
It is easy to find fossils of early molluscs from the Cambrian period of the Paleozoic era (525 Ma) in limestone deposits on our property. The newer rocks that would have held fossils of higher animals have been eroded. We have found a nice specimen of a fossilized Lepidodendron tree, common during the Carboniferous period (305 Ma). Lepidodendron provided more than 90% of the carbon of coal deposits, and was part of what is known as the coal forest flora. They were not truly trees, but are classified as club mosses.
Perhaps the best visual evidence of these collisions can be seen in the road cut-through for the newest portion of US-33 north of Elkins, WV. The layers of rock from the North American plate have been pushed up from their original horizontal orientation by as much as 45-60°. Most of the Allegheny Mountains have eroded from heights greater than the Rocky Mountains to their present 4000-6000' heights, and virtually all seismic activity from mountain formation and plate tectonics has subsided. The largest earthquake recorded in West Virginia was in 1969, and it measured a measly 4.3 on the Richter Scale. It cracked some plaster in a few houses.
Posted by Rob