Supplement - 10Be Raw Data

Bedrock samples were pulverized to 62-250 μm at Northern Colorado University. At the University of Wyoming, magnetic and density separations were used to isolate quartz, and samples were leached with nitric and hydrofluoric acids to remove meteoric 10Be (Kohl and Nishiizumi, 1992; Whitmore et al., 2021; Corbett et al, 2021). Samples were dissolved, spiked with a 9Be carrier, Be was chemically isolated (Corbett et al., 2021), and the 10Be/9Be ratio was measured by Accelerator Mass Spectrometry at PRIMELab (Muzikar, 2003).

Topographic shielding was calculated using the approach of Dunne 1999, and erosion rates were calculated using the CRONUS calculator (version 3, wrapper script version 3.1 and 10Be production by muons version 3.1). Erosion rates reported here use the 10Be production scaling framework of Lal (1991) and Stone (2000). CRONUS inputs needed to reproduce these calculations for other scaling schemes are reported in this Zenodo repository, along with 10Be resutls from PRIMELab.