Rock Blanket

Rock blanket is a layer of larger, graded stones you spread over a slope or ditch to stop soil from washing out. The pieces usually run from about 3 inches up to 12 inches across, and they're placed as a continuous cover instead of a single dumped pile. Under running water or heavy rain, the weight and angular shape of the rock hold the ground in place. You'll often see a geotextile fabric laid down first so dirt can't work its way up through the gaps.

Rock blanket describes how the stone gets placed, so the name doesn't tell you what rock you're getting. It's a continuous cover, usually 6 to 18 inches thick, spread over a slope, ditch, or culvert outfall. The stone itself can be limestone, granite, or river rock depending on what's local to your yard. Different state DOTs spec the same idea under names like riprap, rock lining, or channel protection. Price runs higher than most driveway gravel because the pieces are bigger, harder to screen, and heavier to haul per ton.