Lesson 1 Reading Guide - Vocab
• weathering
• mechanical weathering
• chemical weathering
• oxidation
Weathering
Lesson 1-1• 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.
Weathering and Its Effects
Lesson 1-2• B. Mechanical Weathering• 1. During mechanical weathering,
physical processes break rocks into smaller pieces.
• 2. Mechanical weathering does not change the chemical makeup of therock.
Mechanical Weathering
Lesson 1-2
Lesson 1-2• 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.
Mechanical Weathering (cont.)
Lesson 1-2Mechanical Weathering (cont.)
5. 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.
Lesson 1-3• C. Chemical
Weathering• 1. During
chemical weathering, the materials that make up rocks are changedinto new materials.
Chemical Weathering
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Lesson 1-3• 2. Water is an important agent of chemical weathering becausemost 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.
Lesson 1-3• 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.
Chemical Weathering (cont.)
Lesson 1-4• 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.
What affects weathering rates?
• 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.
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