The Black Mountains, Death Valley, CA, present an opportunity to characterize a magmatic system developed during large-scale intracontinental extension. The goals of this project are to: 1) determine the relationship of magma sources and magma evolution to the geometry and stages of extension, 2) determine the chemical and isotopic signature of new additions to the crust in extensional provinces, 3) determine the crust-mantle mass balance for the southern Basin and Range Province, 4) determine whether or not the geochemistry of the intrusive series is reflected in the eruptive sequence. The PI hopes to: 1) determine the ages of various plutonic bodies through U-Pb, Rb-Sr and fission track studies, 2) measure the Nd, Sr, and Pb isotope, and trace element composition, and 3) apply geobarometry studies. All this wil be done following careful field work.