Geophysics Department Seminar: Alan Rempel
Geophysics Department Seminar
Title: Wetting and Glacier Dynamics
Abstract: At temperatures just below freezing, liquid water wets the interface between ice and sediment and facilitates the growth of pipkrake (also known as needle ice) at the ground surface on crisp mornings. Colder conditions enable ice to infiltrate the underlying pore space and coexist with residual liquid at saturation levels controlled by surface energy and wetting effects, with the latter enabling the unloading of sediment contacts so that segregated ice lenses can form and cause frost heave. The same basic thermo-mechanical interactions are important beneath glaciers and ice sheets, where effective stresses rarely exceed an atmosphere and are comparable to the range encountered in subaerial freezing environments. For particle-size distributions that characterize glacial tills, under ambient thermal conditions ice infiltrates m-scale distances that are sensitive to the changes encountered during transport by glacier sliding. The resulting till entrainment and release sculpt the subglacial landscape and form obstacles that affect glacier flow. This talk explores the resulting connections between wetting and glacier dynamics.