A fast-moving ice or ice stream is a region of an ice sheet that moves significantly faster than the surrounding ice. Ice streams are a type of glacier. They are significant features of the Antarctic where they account for 10% of the volume of the ice. They are up to 50 km wide, 2 km thick, can stretch for hundreds of kilometres, and account for most of the ice leaving the ice sheet.
The speed of an ice stream can be over 1,000 metres per year, an order of magnitude faster than the surrounding ice. The shear forces at the edge of the ice stream cause deformation and recrystallization of the ice, making it softer, and concentrating the deformation in narrow bands or shear margins. Crevasses form, particularly around the shear margins.
Most ice streams have some water at their base, which lubricates the flow. The type of bedrock also is significant. Soft, deformable sediments result in faster flow than hard rock.
Read more about Ice Stream: Antarctica, Greenland
Famous quotes containing the words ice and/or stream:
“A young person is a person with nothing to learn
One who already knows that ice does not chill and fire does not burn . . .
It knows it can spend six hours in the sun on its first
day at the beach without ending up a skinless beet,
And it knows it can walk barefoot through the barn
without running a nail in its feet. . . .
Meanwhile psychologists grow rich
Writing that the young are ones’ should not
undermine the self-confidence of which.”
—Ogden Nash (1902–1971)
“When cats run home and light is come,
And dew is cold upon the ground,
And the far-off stream is dumb,
And the whirring sail goes round,
And the whirring sail goes round;
Alone and warming his five wits,
The white owl in the belfry sits.”
—Alfred Tennyson (1809–1892)