Formation of Longitudinal River Valleys and the Fixing of Drainage Divides in Response to Exhumation of Crystalline Basement

Thomas Bernard, Hugh D. Sinclair, Boris Gailleton, Matthew Fox

Research output: Contribution to journalArticlepeer-review

Abstract

Variations in rock strength act as a first‐order control on mountain landscapes. However, the transient topographic signal of basement exhumation has not been explored. We use model outputs to demonstrate the mobility of drainage divides in mountain ranges in response to the exhumation of basement rocks and the implications for the morphology of river catchments. The exhumation of harder rocks within a catchment reduces upstream channel steepness and erosion rates in contrast to neighbouring catchments. The results are a shift in the orogen‐scale drainage divide towards the harder rocks, and the formation of range parallel longitudinal valleys as neighbouring river networks capture the headwaters of catchments impacted by the harder lithology. Our model outputs provide a process explanation for the initiation of many longitudinal valleys in mountain ranges, and for the pinning of drainage divides on rocks of higher strength as seen the Central Pyrenees, Western Alps or High Atlas.
Original languageEnglish
Article numbere2020GL092210
JournalGeophysical Research Letters
Volume48
Issue number8
Early online date6 Apr 2021
DOIs
Publication statusPublished - 28 Apr 2021

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