Arc-continent collision during the Mesozoic was a dominant tectonic process along the western margin of north America. Jurassic events associated with this process were interpreted to involve a period of short-lived deformation and metamorphism in the late Jurassic, however recent evidence suggests that deformation began in the Middle Jurassic, and that the southern part of the orogen underwent extension while the northern part underwent shortening. This project will examine the timing of orogenesis in the Black Rock Desert of northwest Nevada and the Pine Nut Range of west-central Nevada to address these details, and will employ filed, petrologic and U/Pb and Ar/Ar age dating techniques. Results should provide new data for refining the regional variations in timing of Jurassic deformation.