Transcript Internal and External Forces that Shape the Earth

Internal and External Forces
that Shape the Earth
Chapter 2 Sections 3 and 4
Continental Drift
• Scientific theory explaining how large
landforms were formed.
continental drift
Tectonic Plates- Enormous moving pieces
of the earth’s lithosphere
RING OF FIRE
Divergent Boundary- plates
move apart
How it works
What it
forms/Effe
cts
Magma rises as
tectonic plates
spread apart and
cools, forming new
rock
valleys
Convergent Boundary- plates
move together
How it works
What it
forms/
Effects
Subduction- one Mountains
plate slides under
and
the other
volcanoes
Collision- crumble
into one another
Mountain
ridges
Himalayas
Transform Boundary- plates
slide past one another
San Andreas Fault
How it works
Slides at fault line
What it
forms/Effects
earthquakes
Earthquakes
Earthquakes
Location/ Epicentercreated by plates; point
directly above where the
quake starts
Plates sliding
No new
landforms,
but damage
and
tsunamis
Tsunami- a giant wave in
the ocean
Starts at epicenter and
travels through water
Damage
shores/
ports;
erosion
Volcanoes
Volcan Where gases,
oes magma, and
water pour out of
a crack in the
earth’s surface;
usually along
tectonic plates
Creates lava at
earth’s surface.
Creates
hills,
mountains
, and
islands
Weathering
• physical & chemical processes that
change the characteristics of rock on or
near the earth's surface
Mechanical Weathering- processes that
break rock down into smaller pieces; does not
change composition
• How it works:
ice crystals
build up in a
rock's crack,
creating enough
pressure to
crack the rock
• What it forms:
soil, mud, sand,
silt (sediment)
Chemical Weathering- rock is changed
into new substance as a result of
interaction between elements in the air or
water & minerals in the rock
How it works:
minerals may
react to oxygen &
begin to crumble
minerals may
break down when
combined with
water or carbon
dioxide-forming
weak acids
What it Forms:
rust, acid rain,
decomposed
rocks, soil
Erosion
• weathered material is moved by the action
of wind, water, ice, gravity
Water Erosion- flow of water may pick up loose
sediment, cause abrasion, change the composition of
rock or wave action
• How it works:
motion may
transport
material ; wave
actions can
reduce or
create
beaches
• What it forms:
valleys,
canyons,
deltas, new
beaches, or
more coastline
Wind Erosion- transports & deposits sediment
in other locations
• How is works: winds
pick up particles; dust
storms
• What it forms: sand
dunes, rock sculptures
Glacial Erosion- changing of landforms by
slowly moving glaciers
• How it
works:
glaciers
move down
slope and
move land
• What it
forms:
valleys,
Soil building
• mixing of weathered rock, organic matter,
air, and water through the processes of
weathering & erosion
• How it works: organic matter provides
food- water & air share pores in the soil
• What it forms: different areas for different
agricultural needs