The Aguo Blanca Fault is a major transverse fault of Baja C.Olifornia. Geothermal activity is associated with this fault in the Punta Banda area along the Pacific Coast. The gravity survey described in this paper covers the area I extent of the Valle de Maneadero and port of the Todos Santos Plain north of the northern extension of the fault. Two gravity lows occur in the vicinity of the fault. One low occurs ot the east end of the Volle de Maneadero along the Agua Blanca Fault, and the other occurs north of the fault in the Todos Santos Plain. In oil probability, the eastern low is due to lithologic changes in the basement rock. The gravity low in the Todos Santos Plain is most likely due to a thick sequence of sediments overlying the basement rock. A general east-west trending linearity of the gravity onoma ly occurs in the locality of the fault. The exact location of the Agua Blanca Fault as determined by interpretation of the gravity data coincides with the fault location specified by previous geophysica I investigations. In addition, from the gravity data, the depth to basement rock is calculated to be approximately 6000 feet, assuming a density contrast of 0.3 gm/cm3 • The thick sedimentary fill of the Todos Santos Plain may be acting as a heat resevoir.
