Weathering and Erosion
1. Physical weathering: disintegration or breaking of rock material into small fragments or pieces. In physical
weathering the chemical components of rock remain unchanged.
2. Chemical weathering: Decomposition of rock material due to the chemical reaction of compounds in the
rock with chemicals in the environment. Chemical weathering affect rocks differently because made of
different minerals.
3. Erosion: The processes by which rock and soil materials are loosened or dissolved and transported from
one place to another.
4. Rocks: Mixtures of different elements and chemical compounds that combine in different proportions to
form hard, solid materials of the Earth’s surface.
5. Minerals: The elements and compounds found in rocks are often called minerals. All minerals are solid
and possess a crystal structure.
6. Soil: The mixture of organic component, sand and gravel that makes up the upper surface of the Earth.
7. Deposition: Sediments and materials carried by flowing water, deposited at other places on Earth’s
surface.
8. Process of Weathering: involves the combination of physical and chemical weathering
9. Wind and Water: play a key role in the process of erosion
10. Sieves: Screens with openings of different sizes to separate soil by particle size.
Investigation 1
A) Rocks are physically weathered by breaking them into smaller and smaller pieces.
1. Physical weathering is caused by; growing tree roots, rain, freezing and thawing ice.
2. Physical weathering contributes to formations of soil by breaking large rocks into small pieces.
B) Rocks are chemically weathered when compounds in the rock react chemically with another chemical.
1. Marble gravel chemically weathers faster than most materials.
2. Chemical weathering occurs when: plants release O2 in air, animals release CO2 in air, power plants
release SO2 in air.
C) The combinations of physical and chemical weathering speeds the overall process of weathering.
1. Breaking rocks into smaller pieces, physical weathering exposes more of a rock’s surface to
chemical weathering.
2. It takes thousands of years to weather a rock into smaller particles.
Investigation 2
A) When erosion takes place rocks and soil are transported from one place to another.
1. Hill with a steep slope will erode faster than a less steep slope.
2. Obstacles such as rocks and vegetation will decrease the erosion of the soil from the slope.
B) In order to reduce erosion obstacles:
1. adding vegetation slows water and prevents soil from flowing down the hill
2. adding large stones or fences to decrease the soil from moving down the slope
C) Water and wind help erosion take place
Investigation 3
A) Soil is composed of gravel, sand, and organic material.
B) Particles that make up soil are all different sizes.
C) Sieves can be used to analyze soil by separating soil by particle size