The Appalachian Basin
The central and part of the southern Appalachian Valley and Ridge and Plateau are underlain by an elongate basin that extends from the Great Lakes southwestward to a low broad arch that lies along the southern Tennessee border (Fig. 1). This arch, a branch of the Cincinnati Arch, separates the Appalachian Basin (sensu stricto) from the Black Warrior Basin in Alabama and Mississippi (Thomas, this volume). In its narrower dimension, the Appalachian Basin extends from an eastern edge buried beneath Piedmont thrust sheets (Cook and Oliver, 1981), westward to the crest of the Cincinnati Arch.
The basin is ovoid; its deepest part lies in eastern Pennsylvania. The strata that fill the basin are only a few thousand meters thick on the western basin margin and thicken to about 13,000 m to the north and east (Colton, 1970). Thickness variations reflect the change in composition of basin-filling strata, from strata dominated by limestone and dolomite in the south and west to strata dominated by quartz sand, silt, and clay to the north and east.
The last major synthesis of Appalachian Basin stratigraphy is that published by Colton (1970). This chapter is a generalized summary of the stratigraphic development and filling of the Appalachian Basin, from its inception in the late Precambrian to its deformation at the end of the Paleozoic. Variations in stratigraphic nomenclature reflect the multiplicity of sources used in the compilation. Supplementary tables (Tables 1-7) of stratigraphic terminology contain the names of units not discussed in the text. The
Figures & Tables
Sedimentary Cover—North American Craton
The “sedimentary cover” refers to the stratified rocks of youngest Proterozoic and Phanerozoic age that rest upon the largely crystalline basement rocks of the continental interior. The early chapters of the volume present data and interpretations of the geophysics of the craton and summarize, with sequential maps, the tectonic evolution of the craton. The main body of the text and accompanying plates and figures present the stratigraphy, structural history, and economic geology of specific sedimentary basins (e.g., Appalachian basin) and regions (e.g., Rocky Mountains). The volume concludes with a summary chapter in which the currently popular theories of cratonal tectonics are discussed and the unresolved questions are identified.