1. Lesson 1 Reading Guide - Vocab
Weathering
weathering
mechanical weathering
chemical weathering
oxidation

2. Lesson 1-1 Weathering and Its Effects A. Weathering and Its Effects
1. The chemical and physical processes that change objects on Earth’s surface over time are called weathering.
2. Over thousands of years, mechanical weathering breaks up rocks into smaller pieces.

3. Lesson 1-2 Mechanical Weathering B. Mechanical Weathering
1. During mechanical weathering, physical processes break rocks into smaller pieces.
2. Mechanical weathering does not change the chemical makeup of the rock.

4. Lesson 1-2

5. Lesson 1-2 Mechanical Weathering (cont.)
3. When mechanical weathering breaks a large rock into smaller pieces, the total surface area of the rock increases.
4. Between sandy and clay soils, clay soil holds more water and nutrients because it consists of smaller particles that have more surface area.

6. Lesson 1-2 Mechanical Weathering (cont.)
In ice wedging, water enters cracks in rocks and freezes. Water expands when it freezes and makes the cracks larger.
6. Grinding rock away by friction or impact is called abrasion.
7. Plants growing in a crack in a rock and animals burrowing through loose rock can cause mechanical weathering.

7. Lesson 1-3 Chemical Weathering C. Chemical Weathering
1. During chemical weathering, the materials that make up rocks are changed into new materials.
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8. Lesson 1-3
2. Water is an important agent of chemical weathering because most substances dissolve in water.
3. A(n) acid is a more powerful weathering agent than water.
a. The measure of acidity is called pH.
b. An acid has a pH less than 7.
c. Rain weathers rock because rain is slightly acidic.
d. Acid rain contains pollutants that make its pH less than 5.

9. Lesson 1-3 Chemical Weathering (cont.)
4. Oxygen combines with other elements or molecules during oxidation.
a. Most oxygen used in oxidation comes from the air.
b. The product of oxidation is a(n) oxide.
c. Oxides are useful because they form ores, which people use to obtain metals.
d. The outer part of a rock oxidizes the most because it has more contact with oxygen in the air.

10. Lesson 1-4 What affects weathering rates?
D. What affects weathering rates?
1. Mechanical and chemical weathering depend on water and temperature.
a. Mechanical weathering occurs fastest in areas that have a lot of temperature changes.

11. b. Chemical weathering is fastest where the climate is warm and wet.
c. Overall, weathering occurs fastest in regions near the equator.
2. The type of rock also affects how fast weathering occurs. The most easily weathered mineral in a rock determines how quickly the rock weathers.