  Basal crevasses are macroscopic structural discontinuities at the base of ice
sheets and glaciers. Motivated by observations and the mechanics of elastic
fracture, we hypothesise that in the presence of basal water pressure, spatial
variations in basal stress can promote and localise basal crevassing. We
quantify this process in the theoretical context of linear elastic fracture
mechanics. We develop a model evaluating the effect of shear stress variation
on the growth of basal crevasses. Our results indicate that sticky patches
promote the initiation of basal crevasses, increase their length of propagation
into the ice and, under some conditions, give them curved trajectories that
incline upstream. A detailed exploration of the parameter space is conducted to
gain a better understanding of the conditions under which sticky-patch-induced
basal crevassing likely occurs beneath ice sheets and glaciers.
