Weathering and Erosion
Investigation 1 – PreLab
Weathering and erosion are the two main ways that Earth’s rocky surface is molded and changed. Together they create and reveal marvels of nature from boulders crashing down mountainsides to sandstone arches in the desert to jagged cliffs along the shore.
Erosion control specialists plan soil management or conservation practices, such as crop rotation, reforestation, permanent vegetation, contour plowing, or terracing, to maintain soil or conserve water.
This Investigation is designed to help you to answer the following Focus Questions:
- How are physical and chemical weathering different?
- How do physical and chemical weathering combine to weather rocks?
Note: These questions are located in your SDR at the beginning and end of the Investigation.
As a class, read the Background(s) in the Investigation. When finished, discuss the following concepts as a class:
- Rocks consist of different elements and minerals in different proportions resulting in rocks being different.
- Physical weathering occurs when rocks are broken into smaller pieces.
- Force is required to break rocks into smaller pieces.
- Physical weathering of rock occurs due to the following:
- freezing of water in cracks in a rock,
- forcing of rocks apart by growing tree roots,
- day/night temperature fluctuations that cause rocks to crack,
- loss of the thin surface of rocks exposing surfaces underneath, and
- gravity causing rocks to fall from heights resulting in their breakage.
- Chemical weathering occurs when elements and minerals in rocks react in a chemical reaction with chemicals from the environment.
- Since all rocks are composed of different elements and minerals, not all rocks are subject to the same chemical weathering nor to the same extent of chemical weathering.
- Carbonic acid is a particularly significant chemical that causes chemical weathering.
- Carbonic acid is formed by the reaction of atmospheric carbon dioxide and water or by the reaction of carbon dioxide produced by roots and water in the soil.
LEARN THE LabLearner LINGO
The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.
- physical weathering
- chemical weathering
Note: Definitions to these terms can be found on the Introduction page to the CELL.
SET FOR SUCCESS
- You will investigate the physical and chemical weathering of marble and the mineral, calcium carbonate that marble contains.
- Complete the Recall section in your SDR.
- Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful in the lab.
- After the video, divide into your lab group to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.
Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.
Note: Homework is posted below the video.
You should review the Investigation in preparation for the Lab.