How can landslides block drainage and create lakes?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

lake Lake Ann in North Cascades National Park, Washington, U.S., viewed from the park's Maple Loop Trail. The North Cascades National Park is a large wilderness area that preserves majestic mountain scenery, snowfields, glaciers, and other unique natural features.

Landslides can create lakes by acting as a natural dam that obstructs the flow of a river or stream. When a large mass of rock, soil, or debris slides down a slope and settles across a drainage path, it blocks the water's exit, causing the water to accumulate behind the obstruction and form a lake basin.

A notable example of this process is Lake Sarez in the Pamir Mountains, which was formed as a direct result of a landslide. While landslides are often associated with destructive events, they serve as one of several geological mechanisms—alongside tectonic activity, volcanic processes, and glacial action—that can significantly alter local drainage patterns and create standing bodies of water.1