D.L. Goldsby and D.L. Kohlstedt, Proceedings of 28th Annual Lunar and Planetary Science Conference, Lunar and Planetary Institute, Houston, pp. SEM micrograph of ice deformed to large strain.
Compression is from the upper right to lower left.
Note the occurrence of numerous four-grain junctions indicative of grain switching during superplastic deformation. The scale bar is 50 microns.