Document Type

Article

Author ORCID Identifier

Natalie M. Tanski https://orcid.org/0009-0001-9400-3063

Joel L. Pederson https://orcid.org/0000-0002-8600-4189

Journal/Book Title/Conference

AGU Advances

Volume

6

Issue

1

Publisher

John Wiley & Sons, Inc.

Publication Date

2-19-2025

Journal Article Version

Version of Record

First Page

1

Last Page

28

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Abstract

Erosion can remain active and changing in landscapes long after tectonic drivers have ceased, potentially due to local‐geologic controls, climate changes, or geodynamics. We present new fluvial incision‐ rate histories and terrain analyses of the Colorado River system through the central Colorado Plateau to understand what has caused the variable erosion across this post‐orogenic landscape. Results from new cosmogenic and luminescence dating of fluvial terrace and upland gravel deposits in Glen and Meander Canyons establish incision‐rate histories that are marked by an Early‐Middle Pleistocene erosion hiatus, followed by ∼200 m of rapid incision over the last ∼350 kyr. Projection of fluvial topography from above knickzones of the Colorado River drainage system roughly agree with the observed magnitude of recent incision and reflect a common baselevel fall from Pliocene river integration through Grand Canyon, which is still propagating through the drainage. A response‐time model indicates that baselevel fall from integration likely took 2–4 Myr to reach the central Colorado Plateau and 100s kyr to travel across the study area, potentially accounting for incision rate changes in the fluvial terrace records of Meander and Glen Canyons. The upstream‐ migrating incision has likely been partitioned into multiple waves across the landscape due to the local geologic controls of lava damming, salt tectonics, and heterogenous bedrock. As baselevel fall from Pliocene Colorado River integration diffuses upstream, it can only account for perhaps a quarter of the total ∼2 km of exhumation in the central Colorado Plateau, demanding an unknown driver for significant erosion in the Pliocene.

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