Weathering and Soil
Formation
Chapter 6
WARM-UP #1
•The breaking down of
rocks and other
materials at Earth’s
surface is
ANSWER
• weathering.
WARM-UP #2
•Freezing and
thawing cause
ANSWER
• Ice wedging
VOCABULARY
•Weathering
•Erosion
•Uniformitarianism
weathering and erosion
• Weathering – the process that breaks down
rock and other substances at the Earth’s
surface.
• Erosion – forces of erosion carry the pieces
away…..weathering and erosion work together
to break down and carry away rocks on Earth’s
surface.
vocabulary
•Uniformitarianism –
principles that operate
today operated in the
past
WARM-UP #3
•Which is a cause
of chemical
weathering?
ANSWER
• Acid rain
WARM-UP #4
•Mechanical
weathering is faster
in a climate that is
ANSWER
• warm
VOCABULARY
•Mechanical weathering
•Abrasion
•Ice wedging
MECHANICAL WEATHERING
• Mechanical weathering –
weathering where the rock is
broken into smaller pieces….each
piece is still the same
composition….mechanical
weathering is a slow process
EXAMPLES
• Freezing and thawing, release of pressure,
plant growth, actions of animals, abrasion
• Abrasion – grinding away of rocks by rock
particles carried away by wind, water, ice, or
gravity
• Ice wedging – water seeps into cracks –
expands when it freezes – ice is like a wedge
that breaks the rock apart
WARM-UP #5
•When dead plants
and animals
decay, they form
ANSWER
• humus
WARM-UP #6
•A solid layer of
rock under the
soil is called
ANSWER
• bedrock
VOCABULARY
•Chemical weathering
•Oxidation
•Permeable
Chemical weathering
• Process that breaks down rock
through chemical
changes………..causes are the
action of water, oxygen, carbon
dioxide, living organisms, and
acid rain.
VOCABULARY
• Oxidation – when iron combines with
oxygen in the presence of
water………….rust
• Permeable – rock that is full of tiny
holes…allows water to seep through
easily….permeable rocks will weather
quickly when exposed to chemical
weathering.
WARM-UP #7
•In the United States,
most of the eastern
states are covered
with
ANSWER
• Forest soil
WARM-UP #8
•Living things that
break down dead
organisms are called
ANSWER
• decomposer
VOCABULARY
•Soil
•Bedrock
•Humus
VOCABULARY
• Soil – loose weathered material on
Earth’s surface where plants can
grow
• Bedrock – solid layer of rock below
the soil
• Humus – decayed organic material in
soil
WARM-UP #9
•Soil fertility is a
measure of
ANSWER
how good soil is for growing plants.
WARM-UP #10
•Farmers leave dead
plants in their fields in
the soil conservation
method called
ANSWER
• conservation plowing.
VOCABULARY
•Fertility
•Loam
•Soil horizon
VOCABULARY
• Fertility – measure of how well the
soil supports plant growth
• Loam – soil made up of equal parts
of sand, clay and silt
• Soil horizon – is how the soil
develops into layers ………the layers
differ in color and texture
WARM-UP #11
• The movement of rock
pieces and other materials
on Earth’s surface is called
______________________
______.
ANSWER
• erosion
WARM-UP#12
• The kind of weathering that
breaks rocks into smaller
pieces is
_____________weathering.
ANSWER
• mechanical
VOCABULARY
•Topsoil
•Subsoil
•Litter
•Decomposers
TOPSOIL AND SUBSOIL
• Topsoil – is horizon A ….crumbly,
dark brown soil that is a mixture
of humus, clay and other
mixtures
• Subsoil – is horizon B….clay and
other particles washed down
from horizon A…little humus
LITTER AND DECOMPOSERS
• Litter – is what is left of the plant
before it adds to humus…..leaves,
roots, and the plant itself when it
dies.
• Decomposers – organisms that break
down the remains of dead organisms
into smaller pieces and digest them
with chemicals.
WARM-UP#13
• The scraping of rock by windblown pieces of rock is called
_________________________
_.
ANSWER
• abrasion
WARM-UP#14
•The material on Earth’s
surface in which plants
can grow is
___________________.
ANSWER
• soil
VOCABULARY
• Sod – thick masses of tough roots
at the surface of the
soil……..keeps the soil in place
and held onto moisture.
• Natural resource – anything in
the environment that humans
use
WARM-UP #15
•The B horizon is also
called _____________ .
ANSWER
• subsoil
WARM-UP #16
•In ______________
weathering, the
makeup of rock
changes.
ANSWER
• chemical
VOCABULARY
• Dust Bowl – ruined farmland on
Oklahoma and parts of the
surrounding states…..caused by years
of droughts and lots of plowing
tuned the top soil to dust and it blew
away.
• Soil Conservation – management of
the soil to prevent it’s destruction.
WARM-UP #17
•Different kinds of
rock weather at
different
___________.
• rates
WARM-UP #18
•The last layer of soil
to form is the _____
horizon.
• C
PLOWING
• Contour Plowing – plow the fields along
the curve of the slope….slows runoff and
preserves the soil from erosion.
• Conservation Plowing – disturb the plant
cover and soil as little as possible…dead
weeds and stalks are left in the ground
to help return soil nutrients.
CROP ROTATION
• Farmers plant different
crops in the field each
year………helps maintain
the nutrients in the soil
WARM-UP #19
•Loss of
_____________
causes soil to lose its
fertility.
• topsoil
WARM-UP #20
• One way to keep soil fertile
is to grow a
__________________ kind
of plant every year.
• different