Weathering
Never let the “weathering”
break us down, oh no, let’s go!
Prepared by: S’ Julius S. Dela Cruz
OBJECTIVES
at the end of the lesson, the students should be able
to:
a. describe how rocks turn into the soil
b. differentiate the types of weathering
c. explain the effects of weathering on living things
and the environment
Weathering
Processes that work to
weaken
and break down rock at
Earth’s surface.
Weathering
 Breaks rock into
smaller pieces
• Pebbles
• Sand
• Silt
• Clay
 Changes Earth’s
surface
Types of Weathering
• Mechanical (Physical)
Weathering
• Rocks are broken apart by
physical processes
• Chemical makeup of rock remains
the same
• Chemical Weathering
• Chemical reactions dissolve the
minerals in rocks or change them
into different minerals
Types of Weathering
Mechanical (Physical) Weathering
Plants: Root Pry
• As roots grow, they cause
rocks to split
• Examples
• Sidewalks
• Trees growing in
bedrock
Animals
• Burrowing animals loosen sediment and push it to the
surface to be weathered by additional processes
• Examples:
• Golpher
• Mole
Ice Wedging or Freeze/Thaw
Water EXPANDS as it freezes
The force of the expansion is
strong enough to split rocks
apart
Examples:
Creates huge boulder fields in
mountains
Potholes - big problem for cars
and other vehicles
Natural Acids: Carbonic Acid
• Rainwater reacts with carbon
dioxide in the air or soil
• Breaks down calcite,
Natural Acids: Carbonic Acid
limestone and marble
• Example:
• Acid rain - natural
• Creates underground caves
Natural Acids: Carbonic Acid
• Rainwater reacts with carbon
dioxide in the air or soil
• Breaks down calcite,
Natural Acids: Carbonic Acid
limestone and marble
• Example:
• Acid rain - natural
• Creates underground caves
Natural Acids: Carbonic Acid
• Rainwater reacts with
carbon dioxide in the
air or soil
• Breaks down calcite,
limestone and marble
• Example:
• Acid rain - natural
• Creates
underground caves
Natural Acids: Carbonic Acid
Plant Acids
Some roots and decaying
plants give off acids that
also dissolve minerals in
rock
As the rock weathers,
nutrients become
available to plants
Examples:
Tree roots
Lichen and mosses
Lichen and Mosses
• Do not need soil to grow
• Acids breakdown rocks and
creates soil
Oxygen: Oxidation
• Oxygen with water
dissolve iron minerals
• Turns rocks a yellowish
or orange-brown
• Examples:
• Rust on cars/bikes
(man-made objects)
• Hematite from mineral
lab
• Planet Mars
Exfoliation
• Process where rock
surfaces break off in
sheets or layers
• Caused by pressure
release/temperature
changes
• Examples:
• Exfoliating the
skin
Hydration
• Rock minerals
dissolve in water,
changing the
chemical makeup of
the rock
• Example:
• Rocks at the
bottom of a lake
Abrasion
• The breakdown of
rocks by the
collision of
sediments carried by
moving wind or
water
• Examples:
• River sediment
• Sand blasting
Gravity
• Material moving
down a slope
• Rocks collide against
each other and
against the sides of
the slope
• Example:
• Rock falling down
a mountain
THANKS