A gap is a geological formation that is a low point or opening between hills or mountains or in a ridge or mountain range. It may be called a col, notch, pass, saddle, water gap, or wind gap, and geomorphologically is most often carved by water erosion from a freshet, stream or a river. Gaps created by freshets are often, if not normally, devoid of water through much of the year, their streams being dependent upon the meltwaters of a snow pack. Gaps sourced by small springs will generally have a small stream excepting perhaps during the most arid parts of the year. Water gaps of necessity often cut entirely through a barrier range and riverine gaps may create canyons such as the riverine gaps of the Danube River, Lehigh River Gorge, the Colorado River's Grand Canyon and the Genesee River.…
