The Southern Appalachian Ultradeep Scientific Drill Hole: Progress of Site Location Investigations and other Recent Developments

The southern Appalachian ultradeep core hole (ADCOH) is designed to test modern ideas about the formation of mountain chains along the edges of continents. The faulting, stratigraphy, lithology and out-crop patterns observed during detailed studies of the surface geology in this region have been interpreted in terms of a series of thrust sheets of diverse ages, which were transported northwestward (Fig. 1) over the Iapetan continental margin of North America (Hatcher 1978). Seismic reflection data and interpretations by Clark and others (1978), Cook and others (1979, 1983) and Harris and Bayer (1979) support this interpretation, and reveal a zone of high reflectivity which dips to the southeast beneath portions of the Blue Ridge and Piedmont physiographic provinces. This zone of reflections is correlative with a similar interval known in the sedimentary rocks of the Appalachian foreland some 150 km northwest of the ADCOH study area, and has been interpreted as a regional decollement, serving as the root zone for major thrust faults such as the Brevard.