Analysis of data from the COCORP southern Appalachian seismic reflection survey in the Blue Ridge and Inner Piedmont of northeast Georgia indicates that an unusual seismic discontinuity at relatively shallow depth (about 7.0 km) produces a series of three distinct events arriving with increasing move out at increasing travel times. The events are most easily interpreted as P--P, P--SVk (or SV--P), and SV--SV reflections. Hence the discontinuity, which has previously been interpreted as layered sedimentary or meta-sedimentary strata beneath the crystalline Blue Ridge-Inner Piedmont allochthon, is apparently a prominent shear wave reflector. The results further suggest that additional studies of shear wave propagation in the area may provide valuable information on the lithologic characteristics of the crust. |