Variation in surface elevation of the nisqually glacier Mt. Rainier, Washington

Abstract

Variation in surface elevations of the Nisqually Glacier has been recorded since 1942 by the annual measurement of three profiles across the glacier , designated as nos. 1, 2, and 3, located 0.5, 1.0, and 1.7 miles respectively from the terminus, at approximate mean elevations of 5,250,6,000, and 6,800 feet. A fourth profile, 2-A, located 1.4 miles from the terminus at an approximate mean elevation of 6,450 was measured from 1948 to 1954. These profiles cross the glacier approximately normal to the direction of flow. Additional data are available from measurements made at profiles no. 1 and no. 2 in 1931, 1932 and 1941. The results of these measurements show that a wave or surge has been moving down the glacier .The mean elevation at profile no. 3 began to increase in 1945 and continued through 1951 when it was 83 feet higher than in 1944. The general trend from 1952 to 1959 has been a decrease in elevation with a net change of 30 feet since 1951. The surface elevation at profile no. 2 continued to decrease through 1948, but began to increase in 1949 and continued to do so through 1957 in which year the mean elevation was 102 feet higher than in 1948. The wave became apparent at profile no. 1 in 1954 or 9 years after it first became evident at profile no. 3. The mean elevation has continued to increase and in 1959 was 70 feet higher than in 1954. The increase in surface elevation has been accompanied by a pronounced increase in rate of movement of the glacier .