Download INTERNAL AND EXTERNAL FORCES ON THE EARTH`S SURFACE

INTERNAL AND
EXTERNAL FORCES
ON THE
EARTH’S SURFACE
SLIDE 3
FOR MILLIONS OF YEARS THE SURFACE OF THE EARTH HAS BEEN IN
SLOW BUT CONSTANT MOVEMENT.
THE FORCES THAT CAUSE THIS MOVEMENT ARE INTERNAL
AND
EXTERNAL FORCES.
INTERNAL FORCES WORK BELOW THE EARTH’S SURFACE.
VOLCANISM AND MOVEMENTS THAT BEND, FOLD OR LIFT THE CRUST
EXTERNAL FORCES WORK ON THE EARTH’S SURFACE.
WEATHERING AND EROSION
IT IS ON THE OUTER LAYER OR CRUST OF THE EARTH WHERE
LANDFORMS DEVELOP THAT ARE CREATED BY THESE INTERNAL OR
EXTERNAL FORCES.
SLIDE 4
AT ONE TIME THE CONTINENTS WERE ALL JOINED
AS ONE. THIS WAS PANGEA.
SLOWLY THEY DRIFTED TO THE POSITION THEY
ARE TODAY AND ARE STILL MOVING.
THIS IS CALLED CONTINENTAL DRIFT AND WAS
PROPOSED IN THE 1930S. IT WAS NOT PROVEN
UNTIL THE 1970S.
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TODAY IT IS CALLED PLATE TECTONICS.
HOW DO WE KNOW PLATES ARE MOVING???
CONTINENTS MOVE DUE TO THE PLATES MOVING
INTERACTIVE WEBSITE
• GO TO THE FOLLOWING WEBSITE BY
CLICKING ON THE LINK.
http://pbslearningmedia.org/favorites/
THE CONTINENTS MOVE BECAUSE THEY ARE ON PLATES THAT FLOAT ON THE
EARTH’S MANTLE. THERE ARE 12 OF THESE PLATES.
THERE ARE 4 TYPES OF MOVEMENT ALONG PLATE BOUNDARIES :
1. PLATES MOVING AWAY FROM EACH OTHER
WHICH IS CALLED RIFTING OR DIVERGING PLATES
EXAMPLES- MID-ATLANTIC RIDGE, RIFT VALLEY
IN AFRICA.
(
2. PLATES CONVERGING OR COLLIDING
A. ONE PLATE GOING UNDER ANOTHER –
SUBDUCTION. THIS IS AN OCEAN PLATE
GOING UNDER A CONTINENTAL PLATE.
VOLCANOES AND EARTHQUAKES FORM
ALONG THE BOUNDARIES.
EXAMPLES: ANDES, CASCADE RANGE
TWO OCEAN PLATES COLLIDING ( SUBDUCTION)
ISLAND ARCS ARE FORMED – PHILIPPINES
3. TWO CONTINENTAL PLATES CONVERGING.
THIS IS THE SAME AS #2 BUT INVOLVES 2 CONTINENTAL
PLATES RATHER THAN OCEAN AND COMNTINENTAL.
EXAMPLES: ROCKIES AND ALPS-FOLDED MTS
APPALACHIANS
4. PLATES SLIDING PAST EACH OTHER- FAULTING
CALLED TRANSFORM PLATES.
1.RIFTING OR SPREADING
or
DIVERGING
PLATES MOVING AWAY FROM EACH OTHER
WHICH IS CALLED SPREADING OR RIFTING OR
DIVERGING.
EXAMPLES- MID ATLANTIC RIDGE, RIFT VALLEY
IN AFRICA.
MID-ATLANTIC RIDGE
2. COLLIDING OR CONVERGING
PLATES
A. SUBDUCTION
ONE PLATE GOES UNDER ANOTHER
Example: ONE OCEAN AND ONE CONTINENTAL
VOLCANIC MOUNTAINS ARE FORMED
B. SUBDUCTION
ONE PLATE GOES UNDER ANOTHER
EXAMPLE
: TWO OCEAN PLATES
VOLCANIC ISLAND ARCS ARE FORMED
3. CONVERGING OF TWO
CONTINENTAL PLATES
TWO CONTINENTAL PLATES COLLIDING.
EXAMPLE: ROCKIE MTS, ALPS, HIMALAYAS
APPALACHIANS
4. FAULTING
PLATES SLIDING PAST EACH OTHER
THESE ARE CALLED TRANSFORM
PLATES.
SLIDE 21
INTERACTIVE WEBSITE
• GO TO THE FOLLOWING WEBSITE BY
CLICKING ON THE LINK.
http://pbslearningmedia.org/favorites/
SLIDE 24
INTERACTIVE WEBSITE
CLICK ON THE FOLLOWING WEBSITE:
THEN GO TOP THE TOPIC
EARTHQUAKES, TECTONIC PLATES
AND VOLCANOES.
http://pbslearningmedia.org/favorites/
EXTERNAL FORCES
THESE FORCES WORK ON THE LANDFORMS THAT ARE
CREATED BY INTERNAL FORCES.
NEW LANDFORMS CAN ALSO BE CREATED BY THESE
EXTERNAL FORCES.
THERE ARE TWO TYPES OF EXTERNAL FORCES
WEATHERIN G AND EROSION THAT CAN ALTER THE
SIZE AND SHAPE OF LANDFORMS.
1.WEATHERING
BREAKDOWN OF ROCKS AT OR NEAR THE EARTH’S SURFACE
2 TYPES: PHYSICAL AND CHEMICAL
PHYSICAL1. TREE ROOTS
2. FREEZE AND
THAW CYCLE
EXAMPLES OF PHYSICAL WEATHERING
CHECKERBOARD MESA – UTAH
ZION CANYON
LONE CYPRESS –CALIFORNIA
BRYCE CANYON
17 MILE DRIVE
B. CHEMICAL WEATHERING
1. CHEMICALS IN WATER
DISSOLVE ROCKS.
( CARBONATION)
2. CHEMICALS IN AIR AFFECT
ROCKS.
( OXIDATION)
WITH CHEMICAL WEATHERING
ROCKS CHANGE THEIR
COMPOSITION!!
EXAMPLES OF CHEMICAL WEATHERING
CARBONATION
WEEPING ROCK - ZION
OXIDATION
BRYCE CANYON -UTAH
2. EROSION
THE MOVEMENT OF WEATHERED MATERIAL SUCH AS GRAVEL,
SAND AND SOIL.
THERE ARE 3 TYPES OF EROSION :
A.
WATER
B.
WIND
C. GLACIERS
1. WATER - WEARS AWAY CREATING CANYONS
GRAND CANYON
ERODES AWAY CANYONS AND VALLEYS
ZION CANYON
WATER
2.TRANSPORTS PARTICLES AND CREATES DELTAS
AND BEACHES
NIGER DELTA
BEACH
WIND
1. WEARS SURFACE DOWN
ARCHES
BRYCE CANYON
WIND
2. CREATES NEW LANDFORMS LIKE
SAND DUNES
EGYPT
LAKE MICHIGAN
GLACIERS
1. SHEET
2. MOUNTAIN