High sinuosity bedrock channels: response to rapid incision - examples in SE Spain

Abstract

Three types of high sinuosity bedrock channels are recognised from the Almeria region of southeast Spain: (A) simple incised or ingrown meanders, (B) zones of rapid incisional migration; (C) incised meander cutoffs. Their distributions are related to gradient increases during incision in response to (i) regional tectonics, (ii) local tectonic deformation, and other causes of local base-level changes following (iii) tectonically-induced drainage ponding and breaching, (iv) river capture, (v) eustatic sea-level change. The more complex patterns of incision result from combinations of two or more causes of gradient steepening. The timing of incision, and particularly of cutoffs (Type C), has been assessed through consideration of the terrace sequence. Greatest rates of lateral erosion coincide with periods of maximum net incision. High incision rates control not only the morphology of incising bedrock channels, but also have implications for geomorphic coupling and instability, their spatial effects depending on the headwards propagation rates of incision waves. Although not totally diagnostic, the distribution and properties of incised bedrock channels can be used to infer spatial patterns of the factors causing gradient change, especially those related to tectonic deformation.