been tectonically warped or tilted, the basalts may record irregularities, anomalous gradients, or gradient reversals. Classic examples of basalt-filled channels being used as long-term tiltmeters can be found in studies of late Cenozoic tectonism in the Sierra Nevada Mountains of California (Bateman and Wahrhaftig, 1966). Use of volcanic ashes to date erosional or depositional surfaces are also abundant (Young and Brennan, 1974). Field relations using dated basalts have supported tectonic geomorphologic inference regarding classical geomorphic problems including the development of the western margin of the Colorado Plateau and the evolution of the Grand Canyon (McKee and McKee, 1972; Hamblin et al., 1981).
The tectonic geomorphology of fault-generated topographic fronts can be used to describe long-term tectonic