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脉动型冰川(surging glaciers)的运动速度常显示出惊人的变化。例如阿拉斯加南部的 Variegated冰川每隔18—20年会加快流速。这个脉动型冰川虽然较小,但已进行过广泛的研究,研究者们已对其变化特点作出了解释。他们提出:引起冰川的形态和运动特点变化的原因是冰下溶水的增加。水压力的增高会减小摩擦并导致冰体流动加快。当流域开阔时,冰川的流速就回到起始速度,直至当水体又被截留时速度将再度增加。
The speed of motion of the surging glaciers often shows dramatic changes. For example, the Variegated Glacier in southern Alaska speeds up the flow every 18-20 years. The pulsatile glacier, though small, has undergone extensive research and researchers have explained its changing characteristics. They argue that the reason for the change in the morphology and movement of the glacier is the increase in dissolved water under ice. Increasing water pressure reduces friction and results in faster ice flow. When the watershed is open, the glacier’s velocity returns to the initial velocity, and the velocity increases again until the water is intercepted again.