Environmental Engineering Reference
In-Depth Information
walled and bedrock channels throughout the glacial plumbing system but is free to
develop unconfined deposits beyond the ice margin. Glaciofluvial sediment budgets are
distinguishable by their high point-source concentrations of glacially derived debris, their
high spring melt regime and by a high suspended load of fines which gives meltwater
streams a distinctly milky appearance.
Meltwater is increasingly seen as a more subtle influence on processes regarded
formerly as glacial in nature. Its presence as a widespread water film at the glacier bed is
determined by the glacier's thermodynamic character and pressure-melting regime. This
facilitates sliding, and thereby glacial abrasion, and exerts a major quarrying influence as
a hydraulic jack in bedrock discontinuities. High pore water pressure leads to instability
in all forms of glacial debris and promotes deformation, slumping and flowage.
Plate 15.8
Foliation and shear planes in the Tsidjiore Nouve
glacier, Switzerland, highlighted by contrasting clean and
