Geologic/topographic map of the eastern US. The colors represent different rock units with different geologic ages. Abbreviations for physiographic provinces are: CP, Coastal Plain; Pd, Piedmont; VR, Valley & Ridge (outlined in white); and AP, Appalachian Plateau. The Coastal Plain contains outcrops of Cretaceous and younger sedimentary rocks. The Appalachian Plateau contains outcrops of middle to late Paleozoic (Devonian through Permian) sedimentary rocks. The Valley and Ridge contains outcrops of Paleozoic sedimentary rocks. The Piedmont contains outcrops of Precambrian metamorphic rocks, Paleozoic sedimentary rocks, and Triassic-Jurassic sedimentary and igneous rocks. From the USGS website Tapestry of Time and Terrain.