Figure 1
A) Location of study area. B) Sample collection sites. C) Rendered 87Sr/86Sr surface, with profile locations. D) Surface geology of the Des Moines Lobe as expressed in Hancock and Cerro Gordo counties, northern Iowa (USA) showing variability in parent material of surface sediments (Miller et al., 2008).
Figure 2
Profiles of surface 87Sr/86Sr values along well-sampled transects. See Figure 1C for profile locations.
Figure 3
Residual analysis of observed 87Sr/86Sr (grass) and isoscapes derived from A) bedrock, and B) local water models (Bataille and Bowen, 2012).