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Chapter 8
Mechanical Weathering is
caused by physically
breaking rocks into smaller
pieces
1.
2.
3.
4.
5.
Freezing & Thawing
Animal Actions
Plant Growth
Release of Pressure
Abrasion
Chemical Weathering is
the process that breaks
down rock through
chemical changes
1. Water
2. Oxygen
3. Carbon Dioxide
4. Living Organisms
5. Acid Rain
Break down rock into
smaller pieces
Wear away rock
Make rock smaller
1. Climate
2. Type of Rock
Ice Wedging: process
where wedges of ice in
rocks widen and deepen
cracks
Decomposers
Decomposer: organisms
that break down the
remains of organic material
Ex: earthworms, bacteria,
fungus, small animals
Loam: Soil that is made
of equal parts of sand
and clay
Permeable means it has tiny
connected air spaces here
water can pass through it.
Bedrock: solid layer of
rock beneath soil
Soil Horizons
Clay is smaller particles.
Clay holds more water than
sand
Clay holds too much water
and the plants drown
Sand drains water too
quickly and the plants
dehydrate.
Soil Conservation
Contour plowing
Conservation plowing
Crop rotation
Soil is one of Earth’s most
valuable natural resources
because everything that lives
on land, including humans,
depends directly or
indirectly on soil.
Plants depend directly on
the soil to live and grow.
Humans and animals
depend on plants—or on
other animals that depend
on plants—for food.