large belts of rock bounded by thrust faults piled one on top of another, shortening the crust along the eastern edge of North America in the North Carolina and Tennessee region by as much as . The relative amount of deformation gradually diminishes northward. The fold belt extends northward through Pennsylvania and gradually fades in the vicinity of the New York border. The Kittatinny Mountains in northwestern New Jersey mark the northeasternmost extension of the high ridges of the Valley and Ridge Province. The influence of Alleghanian deformation on the regions east of the Valley and Ridge Province must have been even more intense; however, there is little evidence preserved. Rocks of Mississippian, Pennsylvanian, and Permian age are missing along the Eastern Seaboard. Subsequent erosion The mountains formed by the Alleghanian orogeny were once rugged and high but in our time are now eroded into only a small remnant: the heavily eroded hills of the Piedmont. Sediments that were carried eastward formed the coastal plain and part of the continental shelf. Thus, the coastal plain and Piedmont are largely the byproducts of erosion that took place from 150+ million years ago to the present. Sediments that were carried westward formed the Allegheny and Cumberland Plateau, which in some areas are popularly called mountains but are actually simply uplifted and eroded plateaus. A portion of the Alleghanian mountain system departed with Africa when Pangaea broke up and the Atlantic Ocean began to form. Today, this forms the Anti-Atlas mountains of Morocco. The Anti-Atlas have been geologically uplifted in relatively recent times and are today much more rugged than their Alleghanian relatives. See also Geology of the Appalachians Central Pangean Mountains Mauritanide Belt Inliers and outliers (geology) References Orogenies of North America Carboniferous orogenies Permian orogenies Carboniferous North America Permian North America Geology of North America Appalachian Mountains Allegheny Mountains