Temperature Observations in Bergschrunds and Their Relationship to Cirque Erosion

Abstract

Willard Johnson's bergschrund hypothesis assumes diurnal temperature changes at depth. Direct evidence from continuous temperature records in bergschrunds calls for a modification of this hypothesis. Evidence from northeastern Greenland and Norway shows that air temperatures in an open bergschrund during the summer vary between 30° and 32° F. In Norway diurnal changes of temperature were absent in spite of substantial changes in air temperature outside. New continuous recording instruments have been designed to measure temperatures and the number of times the temperature crosses the freezing point. Further direct evidence is necessary before adopting a thaw-freeze hypothesis.