A barbwire fence across open pasture, strung in a curve to keep cattle from drifting or from bunching up, as cattle do when fences meet at ninety-degree angles, is called a drift fence. The term refers also to a broad fenced lane used to drift cattle to rail junctions. A more common drift fence is the northern snow fence of sienna-colored laths, slats of the sort once used under horsehair-enriched plaster in the walls of a house. The slats are bound together, equally spaced (air ﬂow is essential, or winds and blizzards take the fences down), by strands of twisted wire. Living snow fences, carefully spaced rows of evergreen trees, are used in several areas of the West to keep sections of road prone to drifting from being buried. In plains areas of the worst winds, constructions of spaced two-by-sixes, angled into the wind and anchored to platforms, are employed. All such drift fences are set back from roads and yards to snare drifts. At Denver International Airport, lining the entrance road, a snow fence of bright-orange plastic pierced with baseball-sized holes has lately been used (perhaps temporarily) to replace the originals of wood slats, its color so stunning against fresh snow it can induce a cross-eyed headache.