Question

study coach
identify main ideas work
with a partner. read a
paragraph to yourselves.
then discuss what you
learned in the paragraph.
continue until you and your
partner understand the
main ideas of this lesson.

key concept check

1. describe how does

weathering break down or
change rock?
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438

Explanation:

Weathering breaks down or changes rock through two main types: mechanical (physical) and chemical weathering. Mechanical weathering, like frost wedging (water freezing in rock cracks, expanding to break rock), exfoliation (rock layers peeling due to pressure release), or abrasion (rock particles rubbing against each other), physically breaks rock into smaller pieces without changing its chemical composition. Chemical weathering, such as oxidation (iron - rich rocks reacting with oxygen to form rust - like compounds), hydrolysis (water reacting with minerals to form new substances, e.g., feldspar turning to clay), or carbonation (carbonic acid reacting with carbonate rocks like limestone to dissolve them), alters the rock’s chemical structure, often weakening it and changing its composition. Biological weathering (a subset, involving plants, animals, or microbes) also contributes, like plant roots growing into cracks to widen them (mechanical - biological) or organisms producing acids that chemically weather rock.

Answer:

Weathering breaks down or changes rock via mechanical (physical) weathering (e.g., frost wedging, exfoliation, abrasion) that physically fragments rock without chemical change, chemical weathering (e.g., oxidation, hydrolysis, carbonation) that alters rock’s chemical composition, and biological weathering (e.g., plant root growth, organism - produced acids) that can act mechanically or chemically.