Incorporating lateral variability and extent of paleosols into proxy uncertainty

Abstract

Paleosols (fossil soils) are valuable records of terrestrial climate and environments, and paleosol-based proxies are commonly used to reconstruct past climates and ecosystems. Results from relatively small outcrops or transects or from single vertical sections are frequently scaled up to represent basin-scale processes and conditions, and reconstructions are relied on for temporal changes in those basins. However, uncertainty arising from limited outcrop extent is not currently considered in the standard application of paleosol-based proxies. To explore uncertainty arising from lateral paleosol heterogeneity, we performed a random subsampling analysis on a newly-collected 2.9 km paleosol transect from SW Wyoming, along with two previously-published paleosols. We demonstrate the importance of sampling multiple paleosol profiles, considering lateral geochemical variability, and focusing on relative rather than absolute changes when outcrop-based uncertainty may require it. • Paleosol-based proxies provide unique records of terrestrial climate. • However, outcrop extent and lateral variability are not typically considered. • We statistically resample 3 paleosol transects (1, 1.5, and 3 km). • Sampling >3 profiles from a paleosol decreases proxy uncertainty. • Relative rather than absolute changes in proxy should be commonly used.