Transcript Chap. 8 Weathering & Soil Formation

ROCKS &
WEATHERING
Section 2.1
ROCKS & WEATHERING
 Weathering is the process that breaks down rock
& other substances at Earth’s surface.
 Heat, cold, water, ice, oxygen, carbon dioxide,
freezing, & thawing all contribute to weathering.
 Erosion is the removal of rock particles by wind,
water, ice, or gravity.
 Weathering & erosion work together
continuously to wear down & carry away the
rocks at Earth’s surface.
TYPES OF WEATHERING
 The
principle of uniformitarianism states that the
same processes that operate today operated in
the past.
 The type of weathering in which rocks are
physically broken down into smaller pieces is
called mechanical weathering (physical
process).
 The causes of mechanical weathering include
freezing, thawing, release of pressure, plant
growth, actions of animals, and abrasion.
TYPES OF WEATHERING
Chemical
weathering is the process that
breaks down rocks through chemical
changes.
The causes of chemical weathering
include the action of water (dissolving),
oxygen (oxidation), carbon dioxide
(carbonic acid), living organisms (plant
acids), and acid rain.
RATE OF WEATHERING
 The
most important factors that determine the rate
at which weathering occurs are the type of rock &
the climate.
 The minerals that make up the rock determine how
fast it weathers.
 Both chemical & mechanical weathering occur faster
in wet climates.
 Chemical reactions also occur faster at higher
temperatures.