Weather, Erosion, and Deposition Homework
7th Grade Science: DUE May 4, 2012
/ Name ______
Date ______

Directions: Read each paragraph and complete the Cornell Notes for each paragraph

Changing the Earth’s Surface:

The solid outer layer of the Earth is called the lithosphere. The lithosphere undergoes constant change through natural geological processes. You may recall that forces inside the Earth can cause changes to occur on the Earth’s surface through volcanic activity and faulting. There are also forces that occur on the surface of the Earth that change its surface. These forces include weathering, erosion and deposition.

Main Idea / Details
Changing the Earth’s Surface
  1. What is the lithosphere?
  2. What forces cause constant change to the lithosphere?

Weathering:

Have you ever wondered where the sand on the beach came from? What about the round pebbles you find in a streambed? Sand and pebbles are example of sediment. Sediment are solid pieces of inorganic or organic material that break off larger rock. The breaking down of rock into smaller parts is called weathering. Weathering can be either mechanical or chemical in nature. In mechanical weathering only physical changes occur, but in chemical weathering the rock’s actual composition changes into something new.

Main Idea / Detail
Weathering
  1. What is sediment?
  2. What is an example of sediment?
  3. What is weathering?
  4. What are the two types of weathering?
  5. How are those two types of weathering different?

Erosion:

Erosion is the process by which the weathered rock pieces, or sediments, are carried away. The fundamental force that is responsible for erosion is gravity. Rain and other forms of precipitation fall to the Earth because of gravity. Rivers and smaller streams flow across the land and make their way to the oceans because of the force of gravity. Loose materials such as rocks and boulders are pulled down from cliffs by gravity. Large masses of ice called glaciers flow downward under the force of gravity.

During the process of erosion, sediments are removed from one area of the Earth’s surface and carried to another. This transportation of sediments occurs by several different agents of erosion. Glaciers, wind, water, and gravity are considered the major agents of erosion.

As glaciers move across the Earth’s surface, they erode the land collecting large amounts of rock materials. As the rocks grind against each other they smooth and polish the solid layers below. Often large scrapes and scratches are left in the solid rock layer that is called bedrock.

The wind produces changes in the Earth’s surface by moving loose sand, silt and clay from one place to another. Grains of sand carried by wind can actually sandblast a surface, wearing it away over time. Wind erosion is most common in dry, desert-type areas of the world.

The most important agent of erosion is running water. Running water includes rivers, streams, creeks, melting ice, and surface runoff after a rain. When water falls on a sloping landform, the water flows downhill taking sediment with it. The particles carried by a stream are called the stream’s load. The faster a stream moves, the more load it can carry.

Erosion
  1. What is erosion?
  2. What force is responsible for erosion?
  3. What are the different agents of erosion that transport sediments?
  4. How do glaciers erode land?
  5. How does the wind erode the land?
  6. What types of running water move sediments?

Deposition:

Flowing water carries sediment, but it cannot carry the load forever. Sooner or later, the sediment must settle out. The process by which sediment are laid down in a new location is called deposition. When a river empties into a lake or ocean, it drops its sediment. The heaviest sediment drops first. Then, the lighter sediment settles out in order.

Conclusion

Both erosion and deposition change the shape of the Earth’s surface. Weathering breaks up large rock into smaller pieces called sediment. Erosion moves the materials from place to place. Deposition builds up new landforms as it lays sediment down in a new location. Weathering, erosion, and deposition form a cycle of processes that wears down and builds up the Earth’s surface.

Deposition
What is deposition?

SUMMARY:

Draw a picture of weathering, erosion, and deposition