An Autogenic Cycle of Fluvial Transience in Dipping, Layered Rocks

Abstract

AbstractWe describe an autogenic process by which steady fluvial incision through dipping, layered rocks of different erodibilities cyclically generates migrating drainage divides. We develop an analytical expression for calculating the autogenic periodicity, test it by simulating the incision of idealized strike valleys with a landscape evolution model, and apply our models to estimate the autogenic periodicity within two strike valleys in central Utah. Our analysis suggests that depending on the long‐term incision rate of the San Rafael River network, the autogenic periodicity within the two valleys can overlap with the ∼100 kyr glacial‐interglacial period of climatic forcing, in which case the two different signals would be difficult to separate. Our method should apply to other regions of dipping layered rocks and can be used as a preliminary test to assess whether autogenic or exogenic forcings are more likely to have created a given set of transient features.