Late Miocene Colorado River arrival in the Bidahochi basin supports spillover origin of Grand Canyon

Science
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Abstract

The timing and mechanism of the integration of the Colorado River and incision of the Grand Canyon remain among geology’s enduring controversies. A key question is the configuration of the upper Colorado River watershed between 11 and 6 million years ago. In this study, we present new evidence from zircon uranium-lead geochronology for the arrival of distinctive Colorado–Green River sediment in the Bidahochi basin by 6.6 million years ago derived from the Browns Park Formation. This is coeval with an order-of-magnitude increase in depositional rate, an increase in carbonate strontium isotope (87Sr/86Sr) ratios, the appearance of large fish species characteristic of fast-flowing waters, and other sedimentological changes. This evidence is consistent with the Colorado River supplying water and sediment to the Bidahochi basin before spillover integration of the river through the Grand Canyon.

Suggested Citation

He, J.J., Crow, R.S., Douglass, J.R., Holm-Denoma, C., Vazquez, J.A., Gootee, B.F., Lidzbarski, M.I., Pianowski, L., Gray, H., Heitmann, E., Pearthree, P., House, K., and Dulin, S., 2026, Late Miocene Colorado River arrival in the Bidahochi basin supports spillover origin of Grand Canyon: Science, v. 395, no. 6795, p. 285-295, https://doi.org/10.1126/science.adz6826.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Late Miocene Colorado River arrival in the Bidahochi basin supports spillover origin of Grand Canyon
Series title Science
DOI 10.1126/science.adz6826
Volume 395
Issue 6795
Publication Date April 16, 2026
Year Published 2026
Language English
Publisher AAAS
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 11 p.
First page 285
Last page 295
Country United States
State Arizona, Nevada, Utah
Other Geospatial Bidahochi basin, Colorado River, Grand Canyon
Additional publication details