IMPACT OF LANDSCAPE DEGRADATION ON COSMOGENIC NUCLIDE EXPOSURE DATING OF DIFFERENT TYPES OF GLACIAL MORAINES

Moraine degradation through time, especially in mountain settings, has the potential to affect the accuracy of cosmogenic exposure ages due to surfacing of previously buried erratic boulders. Effects of moraine degradation are rarely evaluated in studies involving cosmogenic exposure dating and may vary among terminal, recessional, and lateral moraines of Late Quaternary glaciations. Cosmogenic exposure ages from glacial valleys within the conterminous western United States have been compiled using the Informal Cosmogenic-nuclide Exposure-age Database (ICE-D), taking advantage of its web feature service to classify moraines as lateral, terminal, or recessional. A set of analytical methods were developed as Python scripts to sort dated moraine boulders and generate camel plots to evaluate age distributions between terminal and lateral moraines. Due to steep ice-proximal slopes and greater height of lateral moraines compared to terminal and recessional moraines, the cosmogenic exposure age variability of boulders on lateral moraines is expected to be greater compared to those on terminal or recessional moraines. Understanding potential variations in the distribution of ages between lateral and terminal moraines improves the assessment of age uncertainties of glacial features.