We collected six samples of exposed streambed sand (250-850 μm) from the lower section of the Colorado River, along a ~450km distance starting south of Hoover Dam and ending near Yuma (see exact locations in data table). All samples collected were prepared at the Cosmogenic Laboratory, Institute of Earth Sciences, Hebrew University of Jerusalem, following standard procedures (Bierman & Caffee, 2001 (doi:10.2475/ajs.301.4-5.326); Kohl & Nishiizumi, 1992 (doi:10.1016/0016-7037(92)90401-4)). Be and Al isotopic ratios were measured at the accelerator mass spectrometry (AMS) facility (ASTER) at CEREGE, Aix-en-Provence, France, and normalized to accepted AMS standards.

This dataset has been carefully reviewed and curated in accordance with PANGAEA's exceptionally high quality standards. However, due to discontinued communication from the authors' side, it did not receive the usual formal approval by the authors and therefore lacks final scientific validation.