During a surge (a period of exceptionally fast flow) of Variegated Glacier in Alaska, the ice not only folded, but also faulted. The diagonal lines from bottom right to top left are low-angle faults called thrusts, where the ice up-glacier overrides the ice below. Folds and thrusts are well-exposed in this image, taken soon after the 1982/83 surge when the surface was still very rough because of the extensive crevassing that occurred at the time. MH