Download Continental Drift and Sea Floor Spreading Notes

Plate Tectonics
Plate Tectonics Pop Quiz
1) What was the name of the scientist that
developed the idea that the continents had
been once joined together in one land mass?
2) What was the name given to supercontinent
that once existed?
3) The idea that the continents have slowly
shifted over time is know as ________.
4-5) Give two pieces of evidence used to
support this theory.
6) Why was his theory rejected?
Plate Tectonics Pop Quiz
1) What was the name of the scientist that
developed the idea that the continents had
been once joined together in one land
mass?
Alfred Wegener
2) What was the name given to
supercontinent that once existed?
Pangaea
3) This idea that the continents have slowly
shifted over time is know as ________.
continental drift
Plate Tectonics Pop Quiz
4-5) Give two pieces of evidence used to
support this theory.
-fossil evidence
-coal fields match up
-climate change/tropical fossils found in
Arctic regions
-mountain ranges line up
-continents fit like a puzzle
6) Why was his theory rejected?
-Wegener could not prove “how” or what
force caused the continent to move
The Plate Tectonics 2 Column
Notes – Guiding Questions
1) Who was Alfred Wegener and
what was his theory?
2) What are pieces of evidence
to support Wegener’s theory?
3) Why was Wegener’s theory
rejected?
1) Who was Alfred Wegener and
what was his theory?
- 1915, German Scientist
-developed idea of
continental drift
-position of continents
have shifted
- one large land mass existed about 300
million years ago
-Pangaea (“all the earth/all lands”)
-over next 100 million years Pangaea
started to break apart
2) What evidence was used to
support his theory?
-continents fit together like a
puzzle (Africa and South America)
-matching rock layers at the edge of the
continents
-mountain ranges line up
2) What evidence was used to
support his theory?
Evidence to support Wegener’s theory –
-fossil evidence on both continents
(Mesosaurus)
-coal fields line up across continents
-glacial evidence in South America
(scratches on rocks)
3) Why was Wegener’s theory
rejected?
-he could not prove “how” the continents
moved
-could not identify what force pushed
continents together or pulled them apart
*Wegener also had to change ideas about
how mountains formed
Plate Tectonic Notes – Continued
pages 141-147
4) What is sonar? (2 facts)
5) What is the mid-ocean ridge?
(3 facts)
6) What is Sea-Floor Spreading (4/5 facts)
-try to describe the process
7) What evidence of sea floor spreading
exists? (try to define/describe each of
them)
4) What is sonar?
sonar
- a device that bounces sound waves
off underwater objects and record their
echoes
- 1950-1960’s – sonar technology allowed
scientists to map the ocean floor
*animation.
5) What is the mid-ocean ridge?
mid-ocean ridge –
-underwater mountains
-connect all along the ocean floor (like seams
on a baseball)
-form the largest mountain chain in the
world
-example: Mid-Atlantic Ridge
6) What is sea floor spreading?
sea floor spreading –
-the sea floor spreads apart along both sides
of a mid-ocean ridge, forming a “crack”
-lava erupts from the crack, then cools and
hardens on each side of the ridge
-new strips of the ocean floor form along
both sides
-the newly formed oceanic crust moves away
from the crack in the ridge
*animation*
7) What evidence of sea floor
spreading exists?
1) molten material
-along the mid-ocean ridge molten
material erupts
-it quickly cools and hardens and looks
like pillows or squeezed toothpaste
*video
7) What evidence of sea floor
spreading exists?
2) magnetic stripes
-the ocean floor is in a pattern of
magnetized stripes
-the stripes match up on opposite sides of
the mid-ocean ridge
-a record of the Earth’s magnetic field
changing on both sides of the mid-ocean
ridge
*animation*
7) What evidence of sea floor
spreading exists?
3) drilling samples
-rock samples were taken on both sides of
the mid-ocean ridge
-the farther away from the ridge, the older
the rock samples
8) What is an ocean trench?
deep ocean trench
-a place where part of the ocean floor sinks
back into the mantle
9) What is subduction at an
ocean trench?
subduction -the actual process of the ocean floor sinking
back into the mantle
-sea-floor spreading and subduction work
together moving the ocean floor like a giant
conveyor belt
-ocean floor is recycled and renewed every
200 million years
10 ) What is the theory of Plate
Tectonics?
Plate Tectonics Theory –
-the Earth’s lithosphere, is broken into
several large slabs, called plates.
-these plates are slowly moving around the
planet.
This theory explains –
-why continents move
-how mountains form
-how volcanoes form
-why earthquakes occur
10 ) What is the theory of Plate
Tectonics?
-links together the theories of continental
drift and sea-floor spreading
-explains how the Earth has evolved over
time
-explains the formation, movements,
collisions and destruction of the Earth’s crust
Major Plates:
-Pacific
-Eurasian
-African
-North American
-South American
-Antarctic
North American
Eurasian
Eurasian
Juan de Fuca
Philippine
Pacific
Arabian
Cocos
IndoAustralian
Caribbean
Nazca
African
South
American
Scotia
Antarctic
Indo-
Austr
Plate Tectonics
-3 types of boundaries
-divergent
-convergent
-transform
Plate Tectonics
divergent boundary
– where plates move apart (divide)
“constructive” – land is being created
What happens/develops:
-sea floor spreading
-mid ocean ridge
Examples:
-Mid-Atlantic Ridge -East African Rift in Red Sea
convergent boundary
–where plates move toward each other (come together)
“destructive” – land is being destroyed
What happens/develops:
-large mountain ranges
-trenches
-subduction
-earthquakes and volcanic eruptions
Examples: Himalaya’s – Indo-Australian plate colliding
with Eurasian plate
transform boundary
– plates slide past each other
What can happen:
-earthquakes occur
Example: San Andreas Fault, CA
Review video link