Flow of Blue Glacier, Olympic Mountains, Washington, U.S.A.*
Journa/ DiG/a ciD/OK)', Vol. 13, No. 68,1974 FLOW OF BLUE GLACIER, OLYMPIC MOUNTAINS, WASHINGTON, U.S.A.* By MARK F. MEIER, (U.S. Geological Survey, Tacoma, Washington g8408, U .S.A.) W. BARCLAY KAMB, CLARENCE R . ALLEN and ROBERT P. SHARP (California Institute of Technology, Pasaciena, California gl 109, U.S.A.) ABSTRACT. Velocity and stra in-rate patterns in a small temperate valley glacier display flow effects of channel geometry, ice thickness, surface slope, a nd ablation. Surface velocities of 20- 55 m /year show year to-year fluctuations of I .5- 3 m /year. Tra nsverse profiles of velocity have the form of a higher-order para bola modified by the effects of flow around a broad bend in the cha nnel, which makes the velocity profile asym metric, with maximum velocity displaced toward the outside of the bend. M arginal sliding rates are 5- 22 m/ year against bedrock a nd nil against debris. Velocity vectors diverge from the glacier center-line near the terminus, in response to surface ice loss, but converge toward it near the firn line because of channel narrowing. Plunge of the vectors gives an em ergence fl ow component that falls short of bala ncing ice loss by a bout I m /year. Center-line velocities vary systematically with ice thickness and surface slope. In the upper half of the reach studied , effects of changing thickness a nd slope tend to compensate, a nd velocities are nearly constant; in the lower half; the effects are cumula tive a nd velocities decrease progressively down-stream .
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