Why can’t we predict the rates of weathering or erosion of bedrock a priori? The rates of these processes affect such important phenomena as soil formation, nutrient release to ecosystems, C sequestration in soils, and toxin release or uptake into regolith. At present we cannot in general predict the depth or chemistry of regolith because we lack the observations and models that might allow such predictions. Furthermore, the processes that control weathering and erosion, even at the base of the Critical Zone (CZ), combine chemical, physical, and biological phenomena that are hard to decouple. In the United States and elsewhere around the world, natural observatories – Critical Zone Observatories – have been established to investigate how water and gas interact with bedrock, regolith, sediments, and biota to define
the Earth’s surface. For example, the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) is the focus of research by more than thirty scientists deriving from fields that include geochemistry, geomorphology, sedimentology, ecology, hydrology, environmental engineering, soil science, and microbiology. Five other such CZ observatories are now operating in the U.S., with more being established in Europe, Australia, and China. At the same time, these CZ Observatories can be compared to less well instrumented sites along environmental gradients to elucidate controls on important CZ processes. Many patterns can be observed by making comparisons across such gradients in environmental variables. Some of these patterns, quantified using intensively collected data from SSHCZO as well as smaller datasets collected across the wider Critical Zone data set (Critical Zone Exploration Network data), suggest answers to first-order questions about how the Earth’s surface changes in response to climatic, tectonic, and anthropogenic drivers.
Brantley, S.L. (2010): Bedrock to Soil: Where Rocks Meet Life in the Critical Zone (Plenary). Goldschmidt .
This Paper/Book acknowledges NSF CZO grant support.