The Black Mountains turtlebacks: Rosetta stones of Death Valley tectonics

The turtleback shear zones can constrain models for crustal extension from map-view as well as cross-sectional perspectives. In map view, the presence of basement-involved thrust faults in the turtlebacks suggest the Black Mountains were a basement high prior to late Tertiary extension. In cross-section, the turtleback geometries and histories are most compatible with models that call on multiple faults rather than a single detachment to drive post-11 Ma extension.