Alleghany Mountains

Alleghany Mountains, a term sometimes used as synonymous with the Appalachian system (see APPALACHIANS), but by some writers applied only to that portion of the system which extends from Pennsylvania to North Carolina, and which forms the watershed between the Atlantic and the Mississippi. It is sometimes used in a still more restricted sense. The ridges are remarkable for their parallelism and regularity, all the main valleys being longitudinal. The general direction is nearly parallel with the Atlantic coast. Their average height in Pennsylvania and Virginia is from 2000 to 2400 feet above the sea; but their original height has been greatly reduced by denudation or erosion. They are composed of stratified rocks of the Silurian, Devonian, and Carboniferous ages. They are rich in coal, iron, and limestone, and their forests supply large quantities of valuable timber.