Comment on Beeson and McCoy

Abstract

The manuscript by Beeson and McCoy explores the role of tilting in affecting bedrock channel profiles, a worthwhile topic, via numerical modeling and GIS analysis. Unfortunately, the main conclusions concerning the geologic history of the Sierra Nevada are refuted by previously published field evidence. The present study concludes that tilting of the northern Sierra Nevada drove incision of the American River system beginning 5 mya (or 1.9 mya); however, the presence of older sediments deep within the canyons of the American River (and other major Sierran rivers) unambiguously falsifies this conclusion (Gabet, 2014): a canyon cannot be younger than the sediments found within it. This study also concludes that the southern Sierra Nevada experienced 2.3 • of tilt over the past few million years, a result contradicted by the slope of a lava flow that C1 ESurfD Interactive commentPrinter-friendly version Discussion paper