The purpose of this research is to estimate the possible range of temperature and pressure of slip plane during faulting and to realize the characteristics and activities of fault by studying the occurrence and petrology of fault rocks. Furthermore, the characteristic and mechanism of structural styles can also be figured out in studying area. The materials in this study come from the drilled core, where located in the riverbank of Wenshuichi in Miaoli area, west Taiwan. They are characterized by the black and well-polished shearing planes and zones and veins, which may be formed by the faulting. Therefore, the characteristics and mechanism of faulting in Miaoli area, the foothills of western Taiwan can be understood by studying these fault rocks.
