Contributions to the Glaciology of the Seward Ice Field, Canada, and the Malaspina Glacier, Alaska

Citation

Leighton, Freeman Beach (1949) Contributions to the Glaciology of the Seward Ice Field, Canada, and the Malaspina Glacier, Alaska. Master's thesis, California Institute of Technology. doi:10.7907/RTYV-8D93. https://resolver.caltech.edu/CaltechTHESIS:03122010-103205758

Abstract

Certain phenomena of the Seward Ice Field and the Malspina Glacier as observed in the summer of 1948 are interpreted in the light of glaciologic literature. Inferences on glacier regimen are drawn from accumulation and ablation measurements. The efficacy of the ablation factors is discussed and analogies are deduced by comparing ablation and meteorological data with those collected by Scandinavian glaciologists on the Vatnajokull, Iceland. The meteorological factors play an overwhelmingly important part in ablation on the ma1uspina Glacier and probably retain their advantage over radiation at a higher elevation on the Seward Ice Field. Distinctions are made between indirect, internal, net end gross ablation. The formation of a glacier water table, and the incidence and dissipation of the winter cold wave on the Seward are discussed. Two contrasting types of differential melt-depressions were noted on the Seward, inclined underwater ice wells and vertical wells not under water. Previous theories of ice- well formation are critically analyzed. The deepening of the ice wells beyond the depth at which the depression is shaded from the sun is believed to be produced by diffuse radiation, with reflected direct radiation playing a minor role. Experiments with artificial ice blocks attest to the importance of vertical gravity settling of debris in ice wells and fail to account for the inclination of the underwater ice wells. Melt-water movement studies were undertaken during a period in July and August. The quantities of melt-water percolating through the firn were measured at various depths and are compared to the ablation record, the meteorological record, and to the time of day in this paper. There is little correlation between the daily melt-water record and the daily sunshine and ablation records. Air temperature is the most significant index of melt-water production. However, the average maximum temperature was reached between 11 and 12 A.M and the average hourly maximum melt-water collected was recorded between 5 and 6 P.M. The fact that the upper firm layers produced less water than deeper firn layers is evidently due to the greater capillary flow and less concentration of melt-water in the upper firn.

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