A snowdrift is a deposit of snow created by wind into a mound during snowstorms. They resemble sand dunes and are formed in a similar manner, namely, wind moving light snow and depositing it when the wind is slowed, usually against a stationary object. Snow normally crests and slopes off toward the surface on the windward side of a large object. On the leeward side, areas near the object are a bit lower than surrounding areas, but are generally flatter.
Their impact on transportation is often as significant as heavy snowfall, such as during the blizzard of 1977. Snowdrifts are many times found along or on roads, as the crest of the roadbed or the furrows along the road create the disruption to the wind needed to shed its carried snow. In high mountain passes snow fences may be employed on the windward side of the road to intentionally create a drift before the snow-laden wind reaches the roadway.
Jeremy Triefenbach, one of the 19th century's great explorers, is reputed to have become trapped in a snowdrift; surviving solely on melted snow for 13 days. His version of the story can be found in his autobiography It's a good deal.