Vocabulary
Weathering and Erosion
Weathering
Mechanical (physical) and chemical processes that change objects on Earth’s
surface over time. Weathering is responsible for limited changes in Earth’s
surface – dissolving, crumbling, or weakening a rock.
Physical
(Mechanical)
weathering
Disintegration or breaking of rock material into small fragments or pieces. In
physical weathering the chemical components of rock remain unchanged.
Chemical
weathering
Decomposition of rock material due to the chemical reaction of compounds in the
rock with chemicals in the environment. Not all rocks are composed of the same
chemicals or minerals, so chemical weathering affects different rocks differently.
Erosion
Process by which rock and soil materials are loosened or dissolved and
transported from one place to another. Erosion is responsible for large scale
changes in the form of the Earth. Rivers, valleys and canyons are created by the
erosion of weakened or disintegrated rock.
Deposition
Process whereby eroded materials are released by their transporting agents
(dropped).
Rocks
Mixtures of different elements and chemical compounds that combine in different
proportions to form hard, solid materials of the Earth’s surface.
Minerals
Elements and compounds found in rocks are often called minerals. All minerals
are solid and possess a crystal structure.
Soil
Mixture of organic material, sand, and gravel that makes up the upper surface of
the Earth.
Agents of erosion
Wind, moving water, gravity, glaciers, man and other animals all move rock
materials.
Agents of
Freeze/thaw, plant roots, wedging by plant roots, day/night temperature
Physical/Mechanical fluctuations, exfoliation, abrasion (wind or water), gravity, and animals burrowing
weathering
all can help break rocks into smaller pieces.
Agents of Chemical
weathering
Water, oxygen, carbonic acid, and other acids all react with elements or
compounds in the rock to make new compounds. Some of these reactions are
called hydration, hydrolysis, oxidation, and carbonation.
Decomposition
Term used in connection with chemical weathering because the compounds in
rocks are chemically changed to different chemical compounds. The original
chemical compounds are “broken apart” and converted into something new.
(Remember the matter is just converted into something else, because matter is
neither created nor destroyed in a chemical reaction, it just changes form.)
Disintegration
Term used in connection with physical weathering because the rock material is
broken down into small fragments or pieces.