Normal fault slip rates were determined for two graben-bounding normal faults in the Northern Elkhorn Hills in the southeastern Carrizo Plain by applying the calibrated model to determine the scarp ages. Slip rates for these faults are a few millimeters per year, and the northwestern fault is about 12 ka old while the other is about 63 ka. We infer that the normal faults form above reverse faults that accommodate increasing contraction adjacent to the SAF as the material enters the Big Bend. The slip rate determination is incorporated into a Geographic Information System that permits us to investigate the relationships between the progessive development of the normal faults, detailed geologic and geomorphic mapping, and mechanical models of the geologic structures in the SAF zone. Side looking airborne radar image of the Carrizo Plain area.
Direction is toward northeast.
The rugged topography of the Temblor Range along the northeast side of the image is a contrast to the flatter Carrizo Plain. The patchwork texture of the Carrizo Plain results from variable grazing and farming practives on different properties. Local relief along the SAF and a more westerly SAF strike increase toward the southeast. In the area of Wallace Creek in the northwest, little local relief is evident and Recent fault activity has been confined to predominantly strike-slip along a narrow zone. Toward the southeast in the Elkhorn Hills, on the other hand, local relief is evident and secondary fault activity increase, possibly the result of increased contraction across the SAF zone caused by a more westerly strike as it enters the Big Bend.