Weathering and Erosion
• Weathering and erosion are two natural
processes that work together to shape the
surface of the earth.
• Weathering is the breaking down of rock into
smaller particles.
• Erosion is when any kind of rock material or
soil is moved to another location.
What do you think contributed to
the formation of this?
Can you see evidence of weathering
and erosion taking place here?
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrape against
each other
Abrasion: mechanical weathering
Which rocks are you more likely to find
on a river bed? Why?
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrape against
each other
Ice wedging: when water in cracks freezes
and causes rocks to split
Ice wedging
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrape against
each other
Ice wedging: when water in cracks freezes
and causes rocks to split
Plant action: when plant roots grow into rocks
and cause them to crack and split
Weathering by plants
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrap against
each other
Ice wedging: when water in cracks freezes
and causes rocks to split
Plant action: when plant roots grow into rocks
and cause them to crack and split
2. Chemical weathering wears away rock by
chemical reaction
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrape against
each other
Ice wedging: when water in cracks freezes
and causes rocks to split
Plant action: when plant roots grow into rocks
and cause them to crack and split
2. Chemical weathering wears away rock by
chemical reaction
 Dissolving by acid
Dissolving by acid
Remember our acid
test? What was
happening to our
rocks?
Stalactites
Stalagmite
Acid rain from pollution
Two types of Weathering
1. Mechanical weathering is when rocks are
broken in smaller pieces by a physical force
Abrasion: when rocks knock or scrap against
each other
Ice wedging: when water in cracks freezes
and causes rocks to split
Plant action: when plant roots grow into rocks
and cause them to crack and split
2. Chemical weathering wears away rock by
chemical reaction
 Dissolving by acid
 Oxidation (rusting)
Chemical weathering
Oxidation
Weathering and Erosion
• Weathering and erosion are two natural
processes that work together to shape the
surface of the earth.
• Weathering is the breaking down of rock into
smaller particles.
• Erosion is when any kind of rock material or
soil is moved to another location.
Erosion
(moving of rock and soil)
• What can move rock and soil from one place
to another?
Erosion
(moving of rock and soil)
• What can move rock and soil from one place
to another?
Moving water; rain runoff, rivers, oceans etc.
Erosion
(moving of rock and soil)
• What can move rock and soil from one place
to another?
Moving water; rain runoff, rivers, oceans etc.
Wind; can carry sand, dust and soil
Erosion
(moving of rock and soil)
• What can move rock and soil from one place
to another?
Moving water; rain runoff, rivers, oceans etc.
Wind; can carry sand, dust and soil
Ice; glaciers and icebergs
Erosion
(moving of rock and soil)
• What can move rock and soil from one place
to another?
Moving water; rain runoff, rivers, oceans etc.
Wind; can carry sand, dust and soil
Ice; glaciers and icebergs
Gravity; mudslides, landslides and gradual creep
Gravity is the underlying force of erosion
Gravity
Sudden
landslide
Gradual creep
Erosion
(moving of rock and soil)
• What can move rock and soil from one place to
another?
Moving water; rain runoff, rivers, oceans etc.
Wind; can carry sand, dust and soil
Ice; glaciers and icebergs
Gravity; mudslides and landslides
Gravity is the underlying force of erosion
• Deposition: when rock or soil is dropped in a new
place.
Can you see evidence of weathering
and erosion here?
How might this rock have formed
cracks?
Describe how
these
gravestones
probably look
different from
when they were
carved? What do
you think is
responsible for
these changes?
Homework
• Describe 4 ways that nature can break
down rocks into smaller pieces.