The Altiplano-Puna of the Central Andes is one of the foremost continental plateaus of the world, and it makes an ideal laboratory for studying the relationship between topography and orogenesis. Prior studies have produced an extensive data base on brittle fault orientations and slip directions that show an apparent regional counter-clockwise rotation of shortening during the last 10 Ma and a change from a thrust regime to a strike-slip regime. This project will continue regional studies northward to assess the possible causes of these changes and to develop further faulting analysis methods.