Compressional wave velocities and densities measured from samples collected along a 5-km-thick, well-exposed, thoroughly studied section of the Valley and Ridge sedimentary sequence of the southern Appalachians are used to generate a synthetic seismogram, which is compared with a reflection profile obtained directly over the stratigraphic section. The excellent agreement between the laboratory synthetic seismogram and the field data clearly demonstrate the usefulness of synthetics generated from laboratory measurements where the geology is known in detail. Seismic modeling indicates that laterally continuous, high-amplitude reflections often originate from the interior of formations, rather than at formation boundaries. High-amplitude, multicyclic reflections often arise from constructive interference of reflections from alternating shales and siltstones or limestones, whereas thick carbonate sequences are generally transparent. The clastic and carbonate rocks of this section are typical of lithologies occurring in sedimentary basins worldwide, and hence the velocity and density data of this study provide a data base for future interpretations of reflection and refraction studies in sedimentary strata of similar age. At elevated pressures, velocities range from 3.6 km/sec for propagation normal to bedding in shale to over 7.0 km/sec in dolostone. Mean densities range from 2,339 kg/m3 for Chattanooga Shale to 2,838 kg/m3 for Knox dolostone. The high anisotropies characteristic of shales are of major importance in modeling the reflection characteristics of sedimentary basins. Surprisingly, anisotropy is also significant in many carbonate rocks and siltstones. A useful diagram relating velocity with composition is presented for various percentages of dolostone, limestone, shale, and sandstone.

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