An important part of Leg 173 was the participation of geologists familiar with the Tethyan margins exposed in the Alps. During the 1990s, important new insights and supporting evidence for marine-based hypotheses of margin development were obtained by fieldwork on Alpine nappes. The sedimentary contacts of synrift or earliest postrift sediments overlying both continental (granite and gneiss) and oceanic (serpentinized peridotite) basements were recognized on the southern Briançonnais continental margin of the Early Cretaceous Valais ocean (Tasna nappe) (Florineth and Froitzheim, 1994; Froitzheim and Rubatto, 1998). Similar contacts of deep-water marine sediments overlying peridotite were recognized on the eastern Apulian continental margin of the Jurassic Piemont-Liguria ocean (Err, Malenco, and Platta nappes) (Froitzheim and Manatschal, 1996; Manatschal and Nievergelt, 1997). This work established the important contribution of low-angle normal and detachment faults to the process of continental extension and mantle exhumation at nonvolcanic rifted margins and allowed palinspastic reconstructions to be attempted. In one location, it was even possible to recognize remnants of the lower continental crust and crust/mantle boundary (Hermann et al., 1997). Later studies included the effects of channelized fluid flow along rift-related detachment faults (Manatschal, 1999; Manatschal et al., 2000). Finally, comparisons have recently been made of geological observations in the Alpine ocean-continent transition zones with geological and geophysical observations of rifted margins at sea (Manatschal and Bernoulli, 1999a, 1999b; Manatschal et al., in press; Wilson et al., in press a). The observed similarity of the sedimentary and tectonic relationships in the two cases is providing a very fruitful means of furthering our understanding of continental rifting processes.