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A water gap is usually an indication of a river that is older than the current topography. The river likely established its course when the landform was at a low elevation or by a rift in earths crust, with a very low stream gradient and a thick layer of unconsolidated sediment. The river therefore established its channel without regard for the deeper layers of rock. A later period of uplift caused increased erosion along the riverbed, exposing the underlying rock layers. As the uplift continued, the river, being large enough, continued to erode the rising land, cutting through ridges as they formed.
- Columbia River Gorge and Wallula Gap, both in Washington State, United States
- Cumberland Narrows, Maryland, United States
- Delaware Water Gap, Pennsylvania and New Jersey, United States
- Manawatu Gorge, New Zealand
- Potomac Water Gap, United States
- Heavitree Gap, Alice Springs, Australia
- Numerous water gaps cutting through the North Downs and South Downs escarpments in southern England, including those of the Mole (at Dorking) and the Great Stour (from Ashford to Sandwich via Canterbury).
- Several water gaps in the eastern Andes, such as Peru's Pongo de Manseriche and Bolivia's Rio Beni near Rurrenabaque.