Periods of dramatically accelerated motion, in which the flow velocity increases suddenly from about 55 cm/d to a peak of 1 00-300 cm/d and then decreases gradually over the course of a day, occurred repeatedly during June and July 1 978-8 1 in Variegated Glacier (Alaska), a surging-type glacier that surged in 1 982-83. These "mini-surges" appear to be related mechanistically to the main surge....