Alleghanian orogeny 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. 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
San Rafael orogeny the San Rafael orogeny. San Rafael orogeny The San Rafael orogeny was an orogeny that affected parts of western Argentina and Chile during the Late Paleozoic. The resulting orogenic belt has a NW-NNW curved form. The San Rafael orogeny might have been linked with the roughly contemporary Gondwanide orogeny of eastern Argentina. Parts of the Choiyoi Group sediments were deformed by the San Rafael orogeny. During the Neogene ancient faults related to the San Rafael orogeny conditioned the geometry of the blocks affected by the Andean orogeny. Some of the plutons of the Elqui-Limarí Batholith were emplaced a context of