Episodic forward prolongation of trunk channels in the Western United States

摘要

Neither the concepts of antecedence nor superposition from an overlying sedimentary surface can explain many drainage networks that traverse ranges in the Basin and Range geomorphic province of the western U.S. Rather, much of the regional drainage network growth has resulted from pluvial lake overflows and basin breaching, causing episodic extensions of the trunk streams in a downstream direction.In this model, the primary role of sediment is to reduce basin volumes, thus increasing the chances of basin breaching by overflow. After basin breaching, a significant base-level drop often results, which leads to the erosion and recycling of sediments, and drainage network permanency. Therefore, remnants of basin fills reaching rim elevations, and other evidence of superposition are unlikely.Drainage network evolution appears to be closely tied to the large Plio-Pleistocene climatic shifts, suggesting that regional drainage integration in the Basin and Range is most likely a Pliocene or Quaternary phenomenon. (C) 2019 Elsevier B.V. All rights reserved.