Essential Questions How does moving water cause erosion? What land features are formed by water erosion and deposition? Chapter4 Lesson 1 Water Erosion

Vocabulary Runoff Rill Gully Stream Tributary Flood plain Meander Oxbow lake Delta Alluvial fan groundwater stalactite stalagmite Karst topography

Lesson Review

How does moving water cause erosion? Erosion begins with a splash of rain. Some water sinks into the ground and some evaporates. The rest of the water RUNS OFF over the land. Runoff -Water moving over land, it carries particles with it. -The more runoff the more erosion.

1- Amount of rain in an area -More rain, more runoff 2- Vegetation - grass, shrubs, and trees reduce runoff by absorbing water and holding soil in place. 3- Type of soil -some types of soil absorb more than other Five factors that affect runoff…

4- Shape of the land -Steep slopes have more runoff than flat land. 5-People’s use of the land - parking lots/buildings absorb no water so there is a lot of runoff, runoff also increases when farmers cut their crops.

FORMATION OF STREAMS AND RIVERS Because of gravity, runoff and the material that it contains flow downhill. As the water moves across the land, it forms rills, gullies, steams and rivers.

What land features are formed by water erosion ? Through erosion, a river creates valleys, waterfalls, flood plains, meanders, and oxbow lakes. Waterfalls---occur where river meets an area of rock that is hard and erodes slowly

Flood Plain Flood Plain- river flowing on gently sloping land, the river spreads out and erodes the land forming a wide river valley. The flat area around the river is a FLOOD PLAIN.

MEANDER Meander - looplike bend the river creates because there is soft rock that erodes easily.

Oxbow Lake Oxbow lake- formed by a meandering river, when part of the meander has been cut off from the river. May form when a river floods.

Water Deposition forms… The sediment and soil that a river carries eventually get deposited somewhere. This sediment creates DELTAS and ALLUVIAL FANS. DELTA- sediment is deposited where a river flows into an ocean or large body of water.

Water Deposition forms… Alluvial Fan- where a stream flows out of a steep narrow mountain, the stream becomes wider and narrower, it is shaped like a fan.

Groundwater Erosion Rain and snow also seep into the ground, called GROUNDWATER. Groundwater also erodes and shapes the land underground. Groundwater- causes chemical weathering. Rain water is usually acidic,it mixes with the carbon gas in the atmosphere creating Carbonic Acid, it breaks apart rock and sediment.

Carbonic Acid Carbonic Acid- breaks apart limestone and starts creating holes and air pockets underground. These air pockets are large holes called CAVES or CAVERNS.

Caves Formations Inside caves you can have deposition of sediment as well. STALACTITE- a deposit that hangs like an icicle from the roof of the cave. STALAGMITE- deposit the builds up from the cave floor upward.

Fun Resources Weathering and Erosion website Study Jams Weathering and Erosion