Soil
Earth Material
Any naturally occurring solid, liquid, or gas matter that makes up the Earth (Ex. Rock, air and water)
Physical Weathering
When rocks break into smaller pieces without changing what the rock is made of
Chemical Weathering
When the minerals in a rock change to a new mineral or other materials
Discovering Soil Materials
Collect a soil sample, add water, allow the soil to settle, observe different layers
Soil
Complex of rock particles of different sizes along with water, air, and organic material
Abrasion
One type of physical weathering, when the rocks rub and scrape against each other
Chemical Reaction
A process in which two or more materials mix in a way that forms new materials
Soil Components as a System
Rocks, humus, living organisms, water, and air
Rock Particle Sizes
Pebble, Gravel, Sand, Silt, Clay
Freezing
Water can flow into the cracks of a rock. When the weather gets cold, the water in the cracks freezes. When water freezes, it expands causing the rock to break into smaller pieces.
Oxygen and Iron
When a rock containing iron comes in contact with oxygen, it can rust (iron oxide), which is softer than other iron minerals.
Main Sources of Chemical Weathering
Water and air
Humus
Organic Matter (Decaying Plant and Animal Material)
Tree roots
Tree roots can grow down into the cracks of a rock. As the roots grow, the roots make the cracks bigger which can make the rock break down into smaller pieces.
Salt water
Salt water can react with minerals in rocks to make new minerals. When the new minerals are softer than the original mineral, holes form.
Physical Weathering Image
Freezing
Living Organisms
Living organisms like worms, insects, animals and bacteria are good for the soil. Their waste products and decomposing bodies provide nutrients and make the soil fertile.
Wind
Wind can blow sand against rocks, which can break rocks down and form interesting shapes
Acid Rain
Carbon dioxide in the air dissolves in water droplets to form acid rain when it falls. The acid causes the calcite in rocks like limestone and marble, which weakens the rocks and forms holes.
Physical Weathering Image 2
Wind blew sand against the rocks