A transect of sites has been established in North America and England as part of the Critical Zone Exploration Network (CZEN) to investigate the rates of soil formation across a climate gradient. Sites reported here are all underlain by an organic-poor, iron-rich Silurian-age shale, providing a constant parent material lithology from which soil is forming. This climosequence includes relatively cold and wet sites in Wales, New York and Pennsylvania, with temperature increasing to the south in Virginia, Tennessee and Alabama. Puerto Rico provides a warm/wet end member for the transect, although this site does not lie on the same shale formation as the Appalachian Mountain sites. Geochemical, mineralogical, and cosmogenic isotope analyses are being completed similarly at all sites to allow direct comparisons and eventual modelling of the weathering processes. Preliminary results from Wales, Pennsylvania and Virginia show soils become more sodium-depleted and the depth to bedrock is significantly deeper at the wet/warm site in Virginia. The fraction of Na lost relative to parent material composition at each site varies linearly as a function of mean annual temperature. Overall, results from the transect will promote a better understanding of how climate changes and human activities impact soil formation rates.
Available at: http://works.bepress.com/ashlee-dere/10/