We employ nonlinear optimization to obtain shallow velocity structure from COCORP seismic reflection profiles in the highly extended Death Valley region, California. We also use group-velocity analysis of regional earthquake surface waves that have traversed in and near the extended domain. When compared with regional models for surrounding provinces, our results show no evidence for significant uplift of the middle crust or removal of the upper crust. We do not find fundamental upper-crustal variations between regions proposed to have widely varying extensional histories. These observations constrain previously proposed extensional mechanisms toward less than extreme amounts of extension.¿ 1997 American Geophysical Union