Skip to main content
U.S. flag

An official website of the United States government

Late Cenozoic climate change paces landscape adjustments to Yukon River capture

July 20, 2020

Late Cenozoic cooling and changes in glacial–interglacial cycle tempo are thought to increase global rates of erosion starting ~3 million years ago (Ma). Bedrock rivers set rates and patterns of erosion in most landscapes, but constraints on river response to late Cenozoic climate change remain elusive. Here, we determine cosmogenic isotope and luminescence ages of well-preserved bedrock terraces along the Fortymile River (Yukon River basin) to reconstruct an ~5 Myr history of fluvial adjustment to late Cenozoic climate and Yukon River headwater capture at 2.6 Ma. Post-capture Yukon River downcutting lowered the Fortymile River outlet, forcing subsequent bedrock incision throughout the Fortymile basin in two pulses, from 2.4 to 1.8 Ma and at ~1 Ma. These pulses of incision disrupted longer intervals of slow river channel sedimentation under near-consistent climate forcing from 4.8 to 2.4 Ma and from 1.8 to ~1 Ma. The Fortymile River delivers sediment to the Bering Sea, where provenance and accumulation rate changes since 4.3 Ma match observed variations in incision. Our results link alluviation and incision to late Cenozoic climate steadiness and change, respectively, and support the hypothesis that climate-forced changes in precipitation and runoff fundamentally control the pace of river incision and landscape erosion.

Publication Year 2020
Title Late Cenozoic climate change paces landscape adjustments to Yukon River capture
DOI 10.1038/s41561-020-0611-4
Authors Adrian Bender, Richard O. Lease, Lee B. Corbett, Paul R. Bierman, Marc Caffee, Tammy M. Rittenour
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Geoscience
Index ID 70237320
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center Geology Minerals