Weathering and Soil
Types of Weathering
Chemical Weathering: a rock
being changed into 1 or more new
compounds
Oxidation- turns the rock into a rusty
color
Acid Rain- Acid in the rain breaks down
the rock
Biological Activity – acids from plants
weather rocks
Dissolution- when the rock dissolves in
a solvent
Carbonic Acid- deterioration of rock
causing it to change color or texture
Spheroidal Weathering- water breaks
down minerals into a spherical shape.
Mechanical Weathering: the breaking
down of a rock, the rock’s mineral composition
does not change.
Unloading and Exfoliation- rock breaks off
in sheets of layer
Abrasion- the wearing down of rock particles
by friction due to water, wind or ice.
Frost Wedging- The process of water
freezing and expanding in the cracks of rocks,
making the cracks larger
Biological Activity-activities by organisms like
animals, plants and humans that cause
weathering. (ie burrowing)
Soil
- Weathered rocks that form the top layer of
Earth’s surface. There are 3 typespedalfer, pedocal, and laterite.
Pedalfer Soil
Pedocal
Soil Composition
Water
Air
Mineral Matter
Organic Matter
Soil Profile
Horizon A (Topsoil)- Loose
and partly decayed organic
matter
Horizon B (Subsoil)- Clay
transported from C horizon
Horizon C- Partially
weathered plant material
Unweathered Plant
Material
Soil and Climate
Temperate Climates
• Pedalfer is formed in temperate climates. Pedalfer is found in the
Eastern US, mostly in forests.
• Pedalfer is rich in iron, has lots of aluminum rich clays and is brown
to red-brown in color.
Desert Climates
• Pedocal is found in dry climates. It can be found in the Western US.
• Pedocal is rich in calcite, and calcium carbonate.
• Light grey-brown
Humid Tropical Climates
• Laterite soil is formed in humid, hot climates in the tropics. Found in
places like Cambodia and Southeast Asia.
• Laterite has lots of iron and aluminum