23.3 Water Shapes the Land

Reading Focus

Key Concepts

• What is the most important factor influencing the ability of a stream to cause erosion?

• What features are formed by surface water erosion?

• What features are deposited by running water?

• What causes groundwater erosion?

Vocabulary

• deposition

• saltation

• flood plain

• meander

• oxbow lake

• alluvial fan

• delta

• stalactite

• stalagmite

• sinkhole

Reading Strategy

Concept Map As you read, draw a concept map showing how moving water shapes the land. Begin with the map below.

The Mississippi River is like an enormous convoy of dump trucks. Every year it carries more than 300 million tons of sediment to the ocean. This amount of sediment would fill a line of dump trucks wrapped nearly three times around Earth! This sediment has been washed away from the surface of the land. As mountains are made by volcanoes or the motions of tectonic plates, erosion begins to wear them away.

The primary force of erosion is gravity. Gravity pulls sediment and water downhill. The end result of erosion is the deposition of sediment. Deposition is the process in which sediment is laid down in new locations.

Most sediment is moved and deposited by flowing water. Flowing water is the major agent of erosion responsible for shaping Earth's surface. Everywhere you look on land, there are features formed by water erosion and deposition.

Figure 12 Streams play an important role in the process of erosion. This stream has cut a deep channel in the soil. The stream banks collapse in mass movement. The soil is then carried away by the stream as sediment.

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