Pipe and Sheet Flow
The flow of water under the glacial surface can have a large effect on the motion of the glacier itself. Subglacial lakes contain significant amounts of water, which can move fast: cubic kilometres can be transported between lakes over the course of a couple of years.
This motion is thought to occur in two main modes: pipe flow involves liquid water moving through pipe-like conduits, like a sub-glacial river; sheet flow involves motion of water in a thin layer. A switch between the two flow conditions may be associated with surging behaviour. Indeed, the loss of sub-glacial water supply has been linked with the shut-down of ice movement in the Kamb ice stream. The subglacial motion of water is expressed in the surface topography of ice sheets, which slump down into vacated subglacial lakes.
Read more about this topic: Ice Sheet Dynamics
Famous quotes containing the words pipe and, pipe, sheet and/or flow:
“Wind and Thistle for pipe and dancers
And never a ploughman under the Sun.
Never a ploughman. Never a one.”
—Hilaire Belloc (1870–1953)
“Pan’s Syrinx was a girl indeed,
Though now she’s turned into a reed;
From that dear reed Pan’s pipe does come,
A pipe that strikes Apollo dumb;
Nor flute, nor lute, nor gittern can
So chant it, as the pipe of Pan;”
—John Lyly (1553–1606)
“Time that scatters hair upon a head
Spreads the ice sheet on the shaven lawn;
Signing an annual permit for the frost....”
—Philip Larkin (1922–1986)
“Flow, flow the waves hated,
Accursed, adored,
The waves of mutation:
No anchorage is.”
—Ralph Waldo Emerson (1803–1882)