Open AccessOn the meltwater genesis of drumlins
Author(s) -
SHOEMAKER EDWARD M.
Publication year - 1995
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.1995.tb00622.x
Subject(s) - geology , meltwater , drumlin , geomorphology , bedrock , erosion , ice sheet , flood myth , ice stream , magnitude (astronomy) , sediment , stream power , hydrology (agriculture) , snow , oceanography , geotechnical engineering , cryosphere , sea ice , philosophy , physics , theology , astronomy
Large subglacial cavities in basal ice. the presumed precursors of depositional drumlins, can be created by corrasion from suspended sediment during a large water sheet outburst flood. The cavities are primarily the result of vortex action. For a given flood discharge the corrasion rate of the ice roof increases with water sheet velocity, V, to a power greater than V 16/3 , Because of ice displacment during a flood, V can vary spatially along a flow line by up to an order of magnitude. The highest velocities normally occur downstream from major bed depressions or near the ice margin. Fields of large drumlins frequently occur at such sites. The process of formation of large subglacial cavities is predicted to be more velocity‐sensitive than the erosion of bedrock. No accurate estimate of water sheet flood volumes can be made at this time but they could be at least an order of magnitude less than the 80 000 km 3 , which was previously estimated.