Transcript What Is Weathering?

What Is Weathering?
• Weathering is the process that
breaks down rocks into
smaller and smaller pieces
• Weathering wears down
mountains and breaks down
statues
What Is Weathering?
• There are two types of
weathering: mechanical and
chemical weathering
What Is Mechanical Weathering?
• It breaks apart rocks without
changing them chemically
• There are 5 types
What Is Mechanical Weathering?
• Rocks formed under pressure
expand and contract when
pressure is released
What Is Mechanical Weathering?
• Ice Wedging occurs when water
seeps into cracks in rock &
freezes…the rock expands and
finally breaks
• This type of weathering causes
potholes in the road
What Is Mechanical Weathering?
Abrasion is the collision of
rocks with one another &
agents such as gravity,
water & wind
What Is Mechanical Weathering?
• Organic Activity known as root pry
• As roots of plants can work their
way into cracks of rock and break
them apart
What is Mechanical Weathering?
• Temperature changes from hot
to cold may aid in weathering
• Rocks expand in hot weather
and contract in cold
What Is Chemical Weathering?
•It breaks apart the rock when
substances chemically react
with the minerals in the rock,
changing it into a different
substance.
•There are 4 types of chemical
weathering
What Is Chemical Weathering?
• Hydrolysis
–minerals change into new
compounds when exposed to
water
What Is Chemical Weathering?
• Oxidation
–Oxygen combines with minerals
What Is Chemical Weathering?
• Carbonation
– change in minerals when they react
with carbonic acid…CO2 + water
– Dissolves limestone forming caves
What Is Chemical Weathering?
• Decaying Plants
–Produce acids that break down
rocks
–Especially mosses and lichens
What Affects the Rate of
Weathering?
• Rock Composition: igneous
and metamorphic rock
weather more slowly
• Amount of Exposure: the
longer a rock is exposed the
faster it will weather
What Affects the Rate of
Weathering?
• Climate: variable weather
conditions accelerate weathering
processes
• Topography: on steep slopes,
rocks are weathered more
quickly