This project is directed at the processes of active mountain-building in Taiwan. As a region of young tectonic activity, Taiwan exhibits high rates of deformation, uplift and erosion. These high rates are advantageous to studies of deformation associated with the mountain-building process. This study is focused on the fold-and-thrust belt of western Taiwan where crustal material from the Asian plate is incorporated into the Taiwan orogen. The investigators are using apatite fission track dating and U-Th/He dating of apatite to determine low-temperature cooling rates of rock throughout the fold-and-thrust belt. Geologic mapping provides structural context for the dating, permitting dating of exhumation of individual thrust sheets. The cooling is related to the rates timing of fault motion and provides information on the kinematic pattern of crustal deformation. To quantify this pattern, the investigators are using structural reconstruction software combined with thermal modeling to relate cooling data, fault motion and temperature history. The use of commercial software with thermal modeling, calibrated to low temperature thermochronomety represents a new innovation in thrust belt interpretation.