Gap (landform)

A gap is a low point or opening between hills, mountains, or within a ridge or mountain range, also called a col, notch, pass, saddle, water gap or wind gap depending on its character. Geomorphologically, a gap is most often carved by water erosion from a freshet, stream or river; gaps fed by freshets typically run dry for much of the year and depend on snowmelt, while those fed by small springs usually keep a small stream flowing year round. Water gaps can cut entirely through a barrier range and, where the river is large enough, carve significant canyons, as seen along the Danube, in the Lehigh River Gorge, in the Colorado River's Grand Canyon and along the Genesee River, exposing the geologic strata beneath in the process.