RATES OF LANDSCAPE EVOLUTION: UNDER THE HOOD OF THE NEW CRONUS-EARTH CALCULATOR

Cosmogenic nuclides are among the most common tools for quantifying rates of landscape evolution and events in the geological history of landscapes. Accuracy and theoretical rigor in the interpretation of cosmogenic nuclide data are thus of critical importance for understanding landscape history. The CRONUS-Earth Project (Cosmic Ray Produced Nuclide Systematics on Earth Project), funded by the NSF, has focused on achieving a physically based understanding of cosmogenic nuclide production and on providing the geomorphic and geologic communities with easy-to-use tools that employ this theoretical understanding in the computation of exposure ages and erosion rates. Experimental data collected by CRONUS-Earth have resulted in major revisions in the scaling of production rates, the methods for dealing with time-varying production, in the understanding of production by muons, and in thermal-neutron parameterization. The calculator itself is based on much-improved calibration data sets, a rigorous experimental basis for quantifying internal and external uncertainties, rigorous uncertainty propagation, rigorous treatment of surface erosion, calculation of ages from single samples at depth, and calculation of ages from depth profiles. These improvements should significantly advance our ability to interpret landscape history and patterns of landscape evolution.