Data of a refraction and a reflection seismic survey in the Black Forest of Southwest Germany are used for extensive one- and two-dimensional modeling. The data are available along approximately the same line, and therefore the same piece of crust is probed by two seismic methods. We utilize this favorable circumstance for detailed model calculations concerning both data sets. In this paper we focus on the lower crust. Its properties vary on the scale of a wavelength, and thus full solutions of the elastic equations are required. We use the reflectivity method for the evaluation of refraction seismograms and numerical solutions of the acoustic wave equation for the reflection response. The lamellae of the lower crust appear as reflecting elements of several hundred meters length randomly distributed in space. Rocks with extremely low velocities (5.6 km/s) must be present, indicating that anisotropy and/or fluids play an important role in the lower crust. Ideas concerning lower crustal formation, evolution, and extinction of lamellaetion are developed. ¿ American Geophysical Union 1987