What is the weathering of the exposed walls by physical and chemical processes followed by slippage of weathered products into river below under the action of gravity called?

Mountains, valleys, and lakes are all landforms, or distinct features of the Earth's surface.  Mountains: A tall, rocky area of land that's generally higher than 2,000 ft. Mountains are a major landform, along with plateaus, plains, and hills. Valleys: A lower part of the land, between two higher parts, which could be hills or mountains. Valleys are a minor landform, along with buttes, canyons, and basins. Lakes: A body of standing inland surface water with a surface area larger than 50 ha. Lakes are a third-order landform, which means they form over second-order landforms. Examples of... Show more

Mountains, valleys, and lakes are all landforms, or distinct features of the Earth's surface. 

Mountains: A tall, rocky area of land that's generally higher than 2,000 ft. Mountains are a major landform, along with plateaus, plains, and hills.
Valleys: A lower part of the land, between two higher parts, which could be hills or mountains. Valleys are a minor landform, along with buttes, canyons, and basins.
Lakes: A body of standing inland surface water with a surface area larger than 50 ha. Lakes are a third-order landform, which means they form over second-order landforms. Examples of third-order landforms include deltas, volcanoes, and gorges. 

Glaciers can form lakes and valleys. As they move slowly along, glaciers carve out pits and scrub the land. When the glaciers melt, water fills the depressions, forming lakes.

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