The Collaborative International Dictionary
Sastrugi \Sas*tru"gi\ Incorrect, but common, var. of Zastrugi.
Wiktionary
n. (plural of sastruga English)
Wikipedia
Sastrugi, or zastrugi, are sharp irregular grooves or ridges formed on a snow surface by wind erosion, saltation of snow particles, and deposition, and found in polar and open sites such as frozen lakes in cold temperate regions. The ridges are perpendicular to the prevailing winds; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges.
Larger features are especially troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring, and can risk breaking equipment—ripples and waves are often undercut and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough.
Usage examples of "sastrugi".
They drove hard over the sastrugi and along ropy lava mounds that served as roads, north past the bulk of Tharsis Tholus, a volcano that was about the size of Mauna Loa, though under the rise of Ascraeus it looked like a cinder cone.