1. Learner Outcomes 1. TSWBAT analyze the causes of erosion. (T/R)
2. TSWBAT identify different types of landforms. (F/P)

2. Monday- STARTING ASSIGNMENT
1) What do you think is happening in this pic?
2) Why do you think it’s happening?
3) How do you think this affects people in LA?
1870
1839
1993
2020

3. Solutions…???

4. Chapter 2
Section 4:
Weathering
&
Erosion

5. EROSION
Occurs when material is moved by wind, water, ice, or gravity

7. Weathering
A process that changes Earth’s rock into smaller pieces called sediment.

8. Changes ONLY the size of rock
Mechanical Weathering:
Changes ONLY the size of rock
Changes a rock into a different rock
Chemical Weathering:

9. mechanical mechanical chemical mechanical chemical
In your groups determine whether the following are examples of mechanical or chemical weathering:
mechanical
1) Hurricane winds break a big rock into little pieces.
2) Plant roots dig into cracks of a rock and split it in two.
3) A chunk of iron is exposed to water and the iron breaks apart.
4) Metal from a drill tears rock from the ground into many pieces.
5) A company dumps toxic waste into a river and nearby rocks begin to break apart faster than usual.
mechanical
chemical
mechanical
chemical

10. Weathering: Picture predictions Weathering: Picture predictions
Name: _____________________________
Directions: Determine whether each picture is an example of mechanical weathering or chemical weathering. Then, predict what caused it (Example: Mechanical weathering - caused by water erosion from a river.) 1) 2) 3) 4) 5) 6)
Name: _____________________________
Directions: Determine whether each picture is an example of mechanical weathering or chemical weathering. Then, predict what caused it (Example: Mechanical weathering - caused by water erosion from a river.) 1) 2) 3) 4) 5) 6)

11. 1)

12. 2)

13. 3)

14. 4)

15. 5)

17. 6)

18. Name: _____________________
Weathering: An External Force That Changes the Earth's Surface
In the soil of the Hawaiian Islands, there is crumbly gray clay that is older than the volcanic rock of the islands themselves. For years, scientists wondered how this had happened. After testing the clay and comparing it to soil in other countries, scientist now believe it comes from a desert in far-off China. Blown across the Pacific ocean by the wind, the clay from China has been deposited on the Hawaiian islands after centuries of windy rainstorms. By providing an important mineral needed for plant growth, the clay enriches Hawaii’s land. This process is still going on. Wind is just one of many external forces that can change the earth’s surface, build and destroy landforms, and affect the soil in which plants grow. The actions of all these forces are usually grouped into two categories: weathering and erosion.
Weathering. Changes in the earth’s surface usually take place very slowly, over thousands or even millions of years. The process of weathering breaks down rock at the earth’s surface into smaller and smaller pieces. While it may take millions of years, weathering can reduce a mountain to just gravel. Depending on the forces involved, weathering is either mechanical or chemical.
Mechanical Weathering. When rock is physically broken apart by forces of nature, the process is termed mechanical weathering. The most common type of mechanical weathering takes place when water gets in the cracks of rocks and freezes to ice. Because water expands by nearly 10 percent when it freezes, the ice widens the crack and eventually splits the rock apart. This process is known as frost wedging. Frost wedging over time is what causes huge parts of a mountainside to break and fall away.
Chemical Weathering. While mechanical weathering can destroy rock, it changes only the physical structure, not the original minerals that make up the rock. Chemical weathering completely alters the rock’s chemical make-up by changing the minerals that form the rock or combining them with new chemical elements. Both kinds of weathering cause the breakdown of rock, but chemical weathering can actually change one kind of rock into another.
The most important forces in chemical weathering are water and carbon dioxide. Commonly, carbon dioxide from the air combines with water to make carbonic acid. When the acidic water seeps into cracks in certain types of rock, such as limestone, it can completely dissolve away the rock. This is how most caves were formed. Another major type of chemical weathering is acid rain. Chemicals in the polluted air combine with water vapor and eventually fall back to earth as acid rain. Acid rain not only destroys forests, pollutes water, and kills wildlife, it also eats away at the surfaces of stone buildings, statues, and natural rock formations. Industrial pollution from factories as well as volcanic activity are the most commonly known causes of acid rain.
Name: _____________________
After reading, write “Agree” or “Disagree” next to each statement, and then underline the relevant piece of text above for each one.
1. In the Hawaiian Islands, there is crumbly gray clay that is older than the volcanic rock of the islands themselves. __________
2. The scientists think that the clay comes from a desert in far-off China. ______________
3. Wind is the only force that changes the earth surface. ______________
4. Changes in the earth’s surface usually take place very quickly. _____________
5. Depending on the forces involved, weathering is either mechanical or chemical. ____________
6. Water expands by nearly 50 percent when it freezes. ____________
7. A rock will not split as plants or trees grow within a frаcture. _____________
8. Chemical weathering can change one type of rock into another type of rock. _____________
9. Most caves were formed by earthquakes that caused deep open spaces to form. ____________
10. Acid rain is caused naturally. ____________

19. Activities: Ch. 2 Continued
1. Complete Hydrologic Cycle Drawing from Friday if not finished.
2. Complete Vocabulary Chart from Friday if not finished.
3. Create a flip chart by choosing SEVEN different landforms found on page (ANY 7 LANDFORMS ON THOSE PAGES) Include the landform’s name, a brief description, and a picture for each landform (Not in Groups). You will need 4 sheets of white paper for flip chart. Title, and 7 sheets for the landforms