Weathering

WeatheringWeathering is the break- is the break-up of rock due to up of rock due to exposure to the exposure to the

atmosphere.atmosphere.

WeatheringWeathering involves two involves two processes that often processes that often

work together to work together to decompose or break decompose or break

down rocks.down rocks.

Chemical and PhysicalChemical and PhysicalWeathering!Weathering!

Chemical weatheringChemical weathering, or , or decomposition, takes place decomposition, takes place when at least some of the when at least some of the

rock’s minerals are changed rock’s minerals are changed into different substances.into different substances.

Chemical processes include Chemical processes include rain, acid etching by plants, rain, acid etching by plants,

oxidizing, and demineralizing oxidizing, and demineralizing by water.by water.

Chemical

Weathering

Physical weatheringPhysical weathering, or , or disintegration, involves physically disintegration, involves physically

breaking rocks into fragments breaking rocks into fragments without changing the chemical without changing the chemical make-up of the minerals within make-up of the minerals within

them.them.

There are four main sources of power There are four main sources of power for physical weathering.for physical weathering.

Gravity, Water, Wind, & WavesGravity, Water, Wind, & Waves

Of these, water appears to be the Of these, water appears to be the leader in changing the surface.leader in changing the surface.

If a particle is loosened by weathering, but stays put, its

just weathering. If it starts moving, its Erosion.

Remember this!: You’ll be quizzed soon!

Physical weathering Physical weathering processes, many of which processes, many of which

are erosional, include are erosional, include some of the following.some of the following.

Frost WedgingFrost Wedging

Frost WedgingFrost Wedging is the freezing is the freezing and thawing of and thawing of

water in water in cracks.cracks.

Physical ExfoliationPhysical Exfoliation

Mechanical Mechanical Exfoliation Exfoliation is the is the

peeling off of peeling off of sheets of rock as sheets of rock as they expand and they expand and

crack.crack.

Crystal Growth WedgingCrystal Growth Wedging

Crystal Growth Crystal Growth WedgingWedging

involves salt involves salt crystals growing crystals growing

from salty from salty waters.waters.

Crystal Growth WedgingCrystal Growth Wedging

Crystal Growth Crystal Growth WedgingWedging usually usually

occurs near occurs near coastlines as it coastlines as it

has on this has on this granite.granite.

Root PenetrationRoot Penetration

Plant roots have to be strong to Plant roots have to be strong to survive the elements.survive the elements.

Root PenetrationRoot Penetration

Powerful plant Powerful plant roots grow into roots grow into rock cracks and rock cracks and cause fractures.cause fractures.

AbrasionAbrasion

Both wind and Both wind and water can water can

cause cause abrasion abrasion as rock as rock

fragments fragments bounce off bounce off each other.each other.

AbrasionAbrasion

This “moon This “moon looking” picture looking” picture of an Antarctic of an Antarctic

rock, shows rock, shows weathering weathering

from the wind from the wind blown sands.blown sands.

Glacial WeatheringGlacial Weathering

Glaciers and avalanches can Glaciers and avalanches can cause weathering as ice and cause weathering as ice and

rock interact.rock interact.

Other Agents of WeatheringOther Agents of Weathering

Things likeThings like flash flash floods, mud floods, mud

slides, slides, landslides, and landslides, and other forms of other forms of mass wasting mass wasting

can cause can cause weathering. weathering.

ErosionErosion

Remember: Remember: Erosion involves Erosion involves removalremoval and and transporttransport..

ErosionErosionRainRain,, wind wind, and , and streamsstreams are all are all

agents of erosion.agents of erosion.

Can you think of any others? Can you think of any others?

A major volcanic eruption A major volcanic eruption would involve both weathering would involve both weathering and erosion. and erosion.