Weathering and Erosion

Weathering Alteration of rock materials during

exposure to air, moisture, and organic matter.

Responsible for limited changes in the Earth’s surface

Two Types of Weathering Chemical Weathering Physical Weathering

Rocks Consists of mixtures of elements and

chemical compounds that combine in different proportions to make different kinds of rocks

Rocks include: marble, quartz and feldspar

Minerals Elements and compounds found in rocks

are called minerals All minerals are solid and possess a

crystal structure Minerals include diamond (carbon and

kaolinite)

Physical Weathering Disintegration or breaking of rock materials into

smaller fragments or pieces Rocks reduced to smaller particles over thousands or

millions of years Chemical components of the rock remain unchanged 6 Important Factors that expose unexposed surfaces

to weathering Freezing and Thawing cycles Plants and Animals Temperature Exfoliation Gravity

PHYSICALWEATHERING

EXPOSES NEW SURFACES TO WEATHERING

!!

Chemical Weathering Chemicals react with the minerals of the

rock to convert them to a new chemical compound Often these new compounds do not have the

same physical properties as the original minerals

Decomposition of rock materials due to chemical reaction of compounds in the rock with the chemicals in the environment

Chemical Weathering Marble consists mostly of calcium

carbonate and quartz if exposed to acids it will reach and chemical weathering will occur Only the calcium carbonate will react not

the quartz

Chemical Weathering Naturally occurring chemical that can

chemically weather marble is Carbonic Acid Carbonic Acid (H₂CO₃) is formed when Carbon Dioxide (CO₂) mixes with Water (H₂O) in the atmosphere

Occurs very slowly over millions of years Hydrochloric and sulfuric acids are not

found naturally and can create acid rain when factors release chemicals into the air

Difference between Physical and Chemical Weathering Rocks are Physically weathered by

breaking them into smaller and smaller pieces.

Rocks are Chemically weathered when compounds in the rock react chemically with another chemical

Physical and Chemical Weather Combine to Weather Rocks By breaking rocks into smaller pieces,

physical weathering exposes more of a rocks surface to chemical weathering.

The combination of the two speeds the overall process of weathering

Investigation Two

Erosion Erosion occurs when rock and soil is

moved from one place to another Large amounts of rock and soil are

transported over large distances Responsible for the formation of rivers,

valleys, canyons, etc. Disintegrates rock and transport it great

distances

Erosion Wind and Water are both capable or moving

large amounts of materials over long distances Wind

Slowly wear down rock until the surfaces of the rock are smooth- windblown sand will help erode rock when particles strike the rock- gradually chipping away

Water Water flow eventually wear down solid rock if the

particles and soil are small enough the water is able to quickly carry them away

Rate of Erosion The amount of erosion that takes places

can be decreased so the overall rate of the erosion- how much erodes in a certain period of time- can be slowed

Anything that tends to protect soil and rock from erosion by wind and water will slow the rate of erosion down

Obstacles on a slope will affect the erosion of soil from the slope Rocks vegetation: trees, grasses, and other plants

What occurs when erosion takes place? When erosion takes place, soil is moved

from one location to another. If erosion occurs on a slope, soil will be washed down the slope

Factors Increasing and Decreasing Erosion Soil from a steep slope will be eroded

more than the soil from a less steep slope.

Obstacles such as rocks and vegetation will decrease the erosion of soil from the slope.

Investigation Three

Soil Mixture of different components

Organic Component Remains of dead plants animals Extremely important providing nutrients for

other plants to grow Inorganic Component

Rocks Result of weathering and erosion

Both weathering and erosion contribute to forming and depositing soil

Weathering, Erosion, and Soil Physical weathering and Erosion tend to

help break up rock into smaller particles due to physical grinding and movement of rock.

New rock surface is exposed to chemical weathering each time a small piece breaks off

Erosion helps transport soil materials so that soil may accumulate in certain locations

Particles in Soil Not all rocks are affected the same way

by weathering and erosion and result in different sized rock fragments in the soil

Pieces of rocks also provide nutrients from the minerals for plants to grow

Soil Components Some components of soil include,

gravel, organic components, and sand

Components Different from Each other Soil components are different chemically

and in size.