Ice Flowage as Revealed by Glacial Striae

Ice flowage in response to the laws of fluid mechanics is shown by analyses of deflection striae found on the exposed floor of the Clements Glacier in Glacier National Park. This is particularly well shown at places where the ice has moved across angular steps and small transverse trenches in the glacier floor. At such places deflection of the ice resulted from differential pressures, which in turn resulted from flow at differential velocities. At several localities it was discovered that this mechanism had been capable of forming eddy-like currents in the ice. An attempt is made to ascertain the minimum thickness of ice necessary to produce such flow. It is found to be between 100 and 200 feet. It is assumed that 150 feet is a reasonable figure. This corresponds to a pressure of 4 kg. per cm.²