When mountains rise slowly, either due to orogenic uplift or other processes (e.g., rebound after glaciation), an unusual feature known as a water gap may occur. In these, erosion from a watercourse such as a river occurs faster than mountain uplift, resulting in a gorge or valley that runs through a mountain range from low-lying country on one side to similar country on the other. Examples of such water gaps include the Manawatu Gorge in New Zealand and the Cumberland Narrows in Maryland, United States.