Mendenhall Glacier basal ice-sediment outcrop samples, 2021

We gathered field observations of debris-rich ice layers from an alpine glacier margin to help inform models of glacial sediment transport across landscapes. Basal ice and entrained sediment samples were taken from the margin of Mendenhall Glacier, Juneau, AK, in August 2021. Along the land-terminating margin of the glacier, we identified five representative outcrops of debris-rich ice with obvious stratigraphic layers. Samples were taken in duplicate at intervals from the base of the debris-rich layers to the clean ice above. After removing the outermost layer of sediment, which is typically enriched by surface melt, we weighed the samples in the field, then transported them back to the Sedimentology and Plant Lab at the Institute of Arctic and Alpine Research in Boulder, Colorado. In the lab, samples were freeze-dried to remove the ice fraction, then weighed again to obtain sediment mass, and thus sediment concentration.