Collaborative Research: Network Cluster: Bedrock controls on the deep critical zone, landscapes, and ecosystems

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The Critical Zone comprises the terrestrial environment from the tree canopy through the soil horizon and down to the base of weathered bedrock. This Critical Zone provides crucial services to humans and ecosystems, including the storage and filtering of groundwater, maintenance of streamflow, and long-term regulation of Earth’s climate. This project, part of the Critical Zone Collaborative Network, will establish the Bedrock Critical Zone Network that spans a wide range of climatic conditions across the continental US, ranging from a subtropical site in the South Carolina Piedmont to warm and dry sites in southern California. The principal goal is to improve knowledge of how subsurface processes in the deep Critical Zone influence water storage potential. In addition, the project will explore how water storage affects ecosystem resilience to disturbances such as prolonged drought. The research will involve direct sampling of subsurface materials via drilling and borehole logging together with non-invasive, indirect imaging techniques. The project will engage teachers, students, and the broader public in information sessions that emphasize the crucial importance of the Critical Zone, including development of a set of interactive 3D visualizations for use by educators.The Critical Zone extends from treetop to bedrock and thus includes both the substrate for life and the organisms that live at Earth’s land surface. In hilly and mountainous landscapes, where erosion at the surface exhumes underlying bedrock, the deepest reaches of the Critical Zone are where bedrock begins the weathering process, where fluids and gases first penetrate and react, where biota begin to colonize and interact with minerals, and where pore space begins to open. This project establishes the Bedrock Critical Zone Network to provide the scientific community with new knowledge of the deep Critical Zone and its feedbacks with surface processes and ecosystems. Observations and modeling at seven sites spanning a wide range of climatic and bedrock conditions in the continental US will test the hypothesis that Critical Zone structure, evolution, and processes are strongly influenced by bedrock conditions at the base of the Critical Zone. Mineralogy, ambient stress, and inherited fractures are influential factors, and these, in turn, are influenced by surface processes like erosion, subsurface flow, and ecosystem productivity. The project will address questions about fundamental deep Critical Zone properties and processes, including: controls on regolith thickness and its variation across landscapes; the relative importance and spatial variability of physical and chemical weathering; how subsurface weathering influences landscape evolution; and how deep Critical Zone water storage affects ecosystem resilience.The project will engage teachers, students, and the broader public on the crucial importance of the Critical Zone ; train scientists at diverse career stages on how to communicate; and promote diversity, inclusion, and equity in Critical-Zone science through targeted programs. The project will undertake an outreach and engagement program that includes a new set of interactive 3D visualizations, called the "Virtual Critical Zone," based on extensive imaging and measurements of roadcuts and quarries. This project will also include hands-on programs for high school teachers and students. All activities will support diversity and inclusion in Critical-Zone science through intentional recruiting and outreach. This project is jointly funded by the Critical Zone Collaborative Network, the Geomorphology and Land-use Dynamics programs in the Division of Earth Sciences, as well as the Education Program in the Geosciences Directorate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.