Plate Tectonics Name: _______________ Date: _________ Period: ___

What is Plate Tectonics? The theory of the ___________, ____________, and ____________ of the earth’s broken crust. The theory of the ___________, ____________, and ____________ of the earth’s broken crust. The ___________________( moving pieces) are made from the rigid ________________ and fluid ___________________ of the crust and upper mantle. The ___________________( moving pieces) are made from the rigid ________________ and fluid ___________________ of the crust and upper mantle. The movement is caused by convection currents of the upper mantle fluid material (magma). The movement is caused by convection currents of the upper mantle fluid material (magma).

15 Major Plates Continental Continental Arabian Arabian Africa Africa Australian Australian North America North America South America South America Antarctica Antarctica Eurasia Eurasia India India Oceanic Pacific Caribbean Coccos Juan de Fuca Philippine Nazca Scotia

Picture of earth’s plates

Lithospheric Plates Pieces of the crust and upper mantle that move Pieces of the crust and upper mantle that move ________________ Crust: ________________ Crust: Thicker, but less dense Thicker, but less dense Felsic minerals Felsic minerals Range from 5 to 35 kilometers thick Range from 5 to 35 kilometers thick _________________ Crust: _________________ Crust: Thinner, but denser Thinner, but denser Mafic minerals Mafic minerals Range from 1 to 5 kilometers thick Range from 1 to 5 kilometers thick

The Father of Continental Drift Alfred Wegener: German scientist Alfred Wegener: German scientist 1912, proposed a theory that the earth did not always look the way it does today. 1912, proposed a theory that the earth did not always look the way it does today. “ the continents drifted, or moved, to their present locations over time” “ the continents drifted, or moved, to their present locations over time” Many observations/ pieces of evidence to support this theory: Many observations/ pieces of evidence to support this theory:

Picture of Al and continental drift

Al’s Evidence #1 The coastlines of western Africa and eastern South America fit together like pieces of a jig-saw puzzle. The coastlines of western Africa and eastern South America fit together like pieces of a jig-saw puzzle.

Al’s Evidence #2 _________________: a fresh water lizard that lived 270 million years ago found only on coastal areas of South America and Africa _________________: a fresh water lizard that lived 270 million years ago found only on coastal areas of South America and Africa

Al’s Evidence #3 _______________: ancient fern fossil found in Antarctica suggested that this place was warmer in the past. _______________: ancient fern fossil found in Antarctica suggested that this place was warmer in the past.

Al’s Evidence #4 Climate Clue: Glacier markings on the southern continents can be connected to make them one smooth mark instead of the random directions seen today Climate Clue: Glacier markings on the southern continents can be connected to make them one smooth mark instead of the random directions seen today

Al’s Evidence #5 Rock Clues: distinctive mineral deposits can be matched up on several continents to show one large area that was connected Rock Clues: distinctive mineral deposits can be matched up on several continents to show one large area that was connected

Al’s Evidence #6 Rock Clues: Similarity of mountain chains and rock formations can be matched up to show one large formation Rock Clues: Similarity of mountain chains and rock formations can be matched up to show one large formation

Al’s Evidence #7 Volcanoes and earthquakes show patterns around the earth. Mostly on coastlines. Volcanoes and earthquakes show patterns around the earth. Mostly on coastlines.

Accepted or Declined For all of Wegener’s evidence, it did not answer the question “how the plates move”. For all of Wegener’s evidence, it did not answer the question “how the plates move”. The scientific community did not ACCEPT his theory. The scientific community did not ACCEPT his theory. Al Wegener died before more concrete evidence was found that gave proof positive to his theory Al Wegener died before more concrete evidence was found that gave proof positive to his theory

New Evidence 1940’s: with any war come new advances in technology 1940’s: with any war come new advances in technology Planes equipped with Sonar flew back and forth across the Atlantic ocean and recorded magnetic abnormalities. Planes equipped with Sonar flew back and forth across the Atlantic ocean and recorded magnetic abnormalities. Recorded the iron minerals in the basalt rock of the ocean floor aligned with polar field of the earth. Recorded the iron minerals in the basalt rock of the ocean floor aligned with polar field of the earth. The alignment presented itself with alternate bands across the seafloor proving polarity switched multiple times during the earth’s history. The alignment presented itself with alternate bands across the seafloor proving polarity switched multiple times during the earth’s history.

Magnetic Field The iron/nickel core of the earth rotates and produces an electrical field. The iron/nickel core of the earth rotates and produces an electrical field. Due to the interaction of the special properties of the mantle, this field intensifies and produces a shield around the earth that protects us from the GAMMA and X-Ray radiation of the sun. Due to the interaction of the special properties of the mantle, this field intensifies and produces a shield around the earth that protects us from the GAMMA and X-Ray radiation of the sun. This field has flipped multiple times in the past producing times of Reverse and Normal polarity. This field has flipped multiple times in the past producing times of Reverse and Normal polarity.

Magnetic Field

Age of the Ocean Floor More researched proved that the ocean floor of the Atlantic was younger than of the continents. More researched proved that the ocean floor of the Atlantic was younger than of the continents. Oldest Continental Rock: _____________ yrs old Oldest Continental Rock: _____________ yrs old Oldest Ocean Rock: _______________ yrs old Oldest Ocean Rock: _______________ yrs old The middle of the ocean has the mid-ocean ridge which is : The middle of the ocean has the mid-ocean ridge which is : Younger Younger Hotter Hotter Higher elevation Higher elevation Than the rock further from the center

Ocean floor

Seafloor Spreading 1950’s: Robert Dietz theorized that the continents moved due to the process of the sea floor creating new material in the center and pushing the continents further apart. 1950’s: Robert Dietz theorized that the continents moved due to the process of the sea floor creating new material in the center and pushing the continents further apart. The process of convection currents inside the asthenosphere bring less dense, hot molten rock up to the surface and push the older, cooler, and more dense rock apart. The process of convection currents inside the asthenosphere bring less dense, hot molten rock up to the surface and push the older, cooler, and more dense rock apart. Called these areas “Spreading Centers” Called these areas “Spreading Centers” Also called “construction Zones” Also called “construction Zones” There were also “Deconstruction Zones” where old seafloor was pushed under continents and recycled. There were also “Deconstruction Zones” where old seafloor was pushed under continents and recycled.

Finalizing a Theory 1960’s: Wegener’s theory became accepted with the help of a Princeton geologist: H. Hess 1960’s: Wegener’s theory became accepted with the help of a Princeton geologist: H. Hess He took the work of Wegener and Dietz and came up with the what, how, and why of plate movements He took the work of Wegener and Dietz and came up with the what, how, and why of plate movements

Types of Plates The plates of the earth move horizontally across the surface The plates of the earth move horizontally across the surface They interact and form different boundaries based on their interactions and their properties They interact and form different boundaries based on their interactions and their properties

DIVERGENT Two plates that move away from each other Two plates that move away from each other Physical Features: Physical Features: Mid ocean ridge Mid ocean ridge Rift Valley Rift Valley Example: Example: Mid Atlantic Ridge (largest ridge system) Mid Atlantic Ridge (largest ridge system) East Africa Rift Valley (Africa is splitting apart) East Africa Rift Valley (Africa is splitting apart)

Divergent

CONVERGENT Two plates that move together Two plates that move together Types depend of properties of the plates Types depend of properties of the plates Subduction Subduction Collision Collision

Convergent

SUBDUCTION One plate is forced under the other due to density difference One plate is forced under the other due to density difference Types: Types: Continent to Ocean: ocean plate will subduct under the continent. Continent to Ocean: ocean plate will subduct under the continent. Physical Feature: a sea trench on the coast of the continent and a chain of volcanic mountains Physical Feature: a sea trench on the coast of the continent and a chain of volcanic mountains Example: The Peru Trench and Andes Mountains Example: The Peru Trench and Andes Mountains Ocean to Ocean: the denser plate will be forced under the other Ocean to Ocean: the denser plate will be forced under the other Physical features: a deep sea trench and an arc of volcanic islands Physical features: a deep sea trench and an arc of volcanic islands Example: Japanese Islands and the Mariana Trench Example: Japanese Islands and the Mariana Trench

Subduction

COLLISION Two continental plates that crumble together and form folded mountains Two continental plates that crumble together and form folded mountains Example: Himalaya Mountains Example: Himalaya Mountains

Transform When plates move horizontally past each other with different speeds and/or direction When plates move horizontally past each other with different speeds and/or direction Physical feature: a fault line Physical feature: a fault line Example: San Andreas Fault Example: San Andreas Fault

Causes of Plate Movement Convection Currents in the mantle are the driving force behind the plate movements. Convection Currents in the mantle are the driving force behind the plate movements. ______________: when the current moves the plate from the mid ocean ridge utilizing the lower elevation of the sea floor. ______________: when the current moves the plate from the mid ocean ridge utilizing the lower elevation of the sea floor. ______________: the sinking edge of the plate is forced down at an subduction boundary and drags the rest of the plate with it. ______________: the sinking edge of the plate is forced down at an subduction boundary and drags the rest of the plate with it.

Convection current

Plate Movement and Continental Growth Using Wegener’s evidence, we have reconstructed the past and found the continents fit together like pieces of a puzzle to form Pangaea Using Wegener’s evidence, we have reconstructed the past and found the continents fit together like pieces of a puzzle to form Pangaea They do not fit perfectly together due to: They do not fit perfectly together due to: Erosion Erosion Weathering Weathering Uplifting Uplifting Volcanic eruptions Volcanic eruptions Deposition of sediments Deposition of sediments

Pangaea The giant landmass that started to break up over 200 million years ago. The giant landmass that started to break up over 200 million years ago. First broke into 2 large pieces: First broke into 2 large pieces: Laurasia: Laurasia: North America North America Eurasia Eurasia Greenland Greenland Gondowana: Gondowana: Africa Africa South America South America Australia Australia Antarctica Antarctica India India Then those pieces continued to break apart and form the present continents Then those pieces continued to break apart and form the present continents

Ancient Cores ______________: The ancient rock core of Pangaea can be found on all continents. ______________: The ancient rock core of Pangaea can be found on all continents. These cores have been buried under secondary continental growth from accumulation of deep sea sediments, igneous rock, river sediments, and terranes These cores have been buried under secondary continental growth from accumulation of deep sea sediments, igneous rock, river sediments, and terranes

Craton