weathering and erosion

Weathering is the

breaking down of

rocks, soil and

minerals as well as

artificial materials

through contact

with the Earth's

atmosphere, biota

and waters.

Temperature

Rainfall

Plants

Animals

Physical

Weathering

Chemical

Weathering

Biological

Weathering

Physical

weathering, also

known as

mechanical

weathering, is the

class of processes

that causes the

disintegration of

rocks without

chemical change.

Expansion and contraction

of rocks is caused by

temperature changes. As

some minerals expand more

than others, temperature

changes set up differential

stresses that eventually

cause the rock to crack

apart. Because the outer

surface of a rock is often

warmer or colder than the

more protected inner

portions, some rocks may

weather by exfoliation – the

peeling away of outer

layers.

Severe frost shattering

produces huge piles of

rock fragments called

scree which may be

located at the foot of

mountain areas or

along slopes. Frost

weathering is common

in mountain areas

where the temperature

is around the freezing

point of water.

In pressure release,

also known as

unloading, overlying

materials (not

necessarily rocks)

are removed (by

erosion, or other

processes), which

causes underlying

rocks to expand and

fracture parallel to

Chemical weathering

changes the

composition of rocks,

often transforming them

when water interacts

with minerals to create

various chemical

reactions. Chemical

weathering is a gradual

and ongoing process as

the mineralogy of the

rock adjusts to the near

surface environment.

Within the weathering

environment chemical

oxidation of a variety of

metals occurs. The

most commonly

observed is the

oxidation of Fe2+ (iron)

and combination with

oxygen and water to

form Fe3+ hydroxides

and oxides such as

goethite, limonite, and

hematite.

Rainfall is acidic

because atmospheric

carbon dioxide

dissolves in the

rainwater producing

weak carbonic acid. In

unpolluted

environments, the

rainfall pH is around 5.6.

Acid rain occurs when

gases such as sulfur

dioxide and nitrogen

oxides are present in

A number of plants and

animals may create

chemical weathering

through release of

acidic compounds, i.e.

the effect of moss

growing on roofs is

classed as weathering.

Mineral weathering can

also be initiated and/or

accelerated by soil

micro-organisms.

In geomorphology

and geology, erosion

is the action of

exogenic processes

(such as water flow or

wind) which remove

soil and rock from one

location on the Earth's

crust, then transport it

to another location

where it is deposited.

Flowing Water

Wind

Sea Waves

Formation of

Components of

Soil

Construction

Materials

Landscapes

People Killed by

Flowing Water

Damage to

Human

Activities

Damage to

Buildings

Information:

International Lower

Secondary

Geography 3

The Big Book of

Knowledge

Wikipedia

Pictures:

Google Images