The unsorted sediment deposited directly below a glacier, which exhibits a wide range of particle sizes, from fine clay to rock fragments and boulders. The rate of till flow beneath a glacier is thought to depend on basal shear stress and on the effective pressure N, defined as the difference between overburden pressure and the interstitial pore water pressure within the sediments. See Evans et al. (2006) Earth Sci. Revs 78, 1–2.
Subjects: Earth Sciences and Geography.