THE
THEORY OF
PLATE TECTONICS
CRUZ, Emmanuel Sebastien P.
DANTIS, Aurel Jared C.
YADAO, Jeries Dylan T.
INTRODUCTION
 The word tectonics came from the Greek word τεκτον (tekton

– “to build; builder”). This word is also the o...
 Simply put, continental drift is the large-scale movements of

continents and the ocean basins throughout geologic time....
 Late in the Triassic Period (approx. 200-250 m.y.a.),

Pangaea broke into fragments, and the fragments gradually
drifted...
Please watch

carefully
as we show
you how South

America

was once united with

Africa.
See Animations…
Next
Before

After
Continental Drift: Frame by Frame
(GIF Animation)
THE CONTINENTAL DRIFT THEORY
 Ferromagnetic minerals, such as magnetite, acquire a

permanent magnetization or magnetic o...
 It is a theory dealing with the dynamics of the lithosphere,

formulated in the 1960s.
 It states that Earth has a rigi...
 Gypsum

 Fossils

 Salt

 Glossopteris fern
 Mesosaurus

 Other Evidences

 Lystrosaurus

 SONAR (sound navigatio...
Coal with
fossilized
fern

Salt deposits in Dead Sea

A valley glacier
Mesosaurus braziliensis
An sonar being deployed in the ocean

Restored
skeleton
of Cynognathus
 Mid-ocean ridges
 Underwater system of mountain ranges
 Usually has a rift or valley running along its spine
 Resembl...
Hotspots on the Lithosphere
Cross-section of some of Earth’s
layers
THE BOUNDARIES

Plates interact with each other at
sites called boundaries. There are
three kinds of boundaries: divergent...
THE BOUNDARIES

• Divergent boundaries are sites where plates move away
from each other.
• Convergent boundaries are sites...
THE BOUNDARIES
• Divergent boundaries are sites where plates move away
from each other.
• As plates move apart at a diverg...
• Convergent boundaries are sites where plates move
toward each other.
• Two oceanic plates: the older, denser plate is
su...
• Transform boundaries are sites where plates slide past
each other, creating a lot of friction in the process.
• The majo...
Divergent

Convergent

Transform
THANK YOU FOR
LISTENING!
(we do hope you listened…)

Content from Encyclopedia Britannica Ultimate Reference Suite 2011
an...
Continental Drift and Plate Tectonics
Continental Drift and Plate Tectonics
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Continental Drift and Plate Tectonics

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  • Continental Drift and Plate Tectonics

    1. 1. THE THEORY OF PLATE TECTONICS CRUZ, Emmanuel Sebastien P. DANTIS, Aurel Jared C. YADAO, Jeries Dylan T.
    2. 2. INTRODUCTION  The word tectonics came from the Greek word τεκτον (tekton – “to build; builder”). This word is also the origin of other tect words, such as architect.  The very first detailed proposal of an idea along these lines as the plate tectonics theory was made by Alfred Lothar Wegener in 1911, under the name ―Continental Drift‖.  Wegener argued that there was once a supercontinent (which he named Pangaea – meaning ―all lands‖) which split up over millions of years and gradually ―drifted‖ over to their current places on earth; at a rate of a few centimeters/year.
    3. 3.  Simply put, continental drift is the large-scale movements of continents and the ocean basins throughout geologic time.  This theory was the most important precursor to the development of the plate tectonics theory.  The first truly detailed theory of this kind was proposed in 1911 by Alfred Wegener, a German meteorologist. He brought together a vast array of paleontological and geologic data and argued that throughout most of geologic time, there was only one continent – Pangaea.
    4. 4.  Late in the Triassic Period (approx. 200-250 m.y.a.), Pangaea broke into fragments, and the fragments gradually drifted away from each other.  The Americas drifted westward, forming the Atlantic Ocean  The Indian block drifted across the equator to merge with Asia  In 1937, Alexander Du Toit, a South African geologist, picked up Wegener’s ideas and suggested two primordial continents – Laurasia in the north, and Gondwanaland in the south.  One of the evidences that made this theory very strong is the sameness or congruency of the edges of various shorelines on Earth, such as South America and Africa. See Animations…
    5. 5. Please watch carefully as we show you how South America was once united with Africa. See Animations…
    6. 6. Next Before After
    7. 7. Continental Drift: Frame by Frame (GIF Animation)
    8. 8. THE CONTINENTAL DRIFT THEORY  Ferromagnetic minerals, such as magnetite, acquire a permanent magnetization or magnetic orientation when they crystallize. The direction of their magnetization is the same as the direction of Earth's magnetic field at the time and place of crystallization.  Studies about this magnetism conducted by Stanley K. Runcorn, Patrick M. Blackett, and others, unearthed a ―polar wandering curve‖ indicating that the magnetic poles were in different places at different times.  This could be explained either by the migration of the magnetic pole itself (that is, polar wandering) or by the migration of Europe relative to a fixed pole (that is, continental drift).
    9. 9.  It is a theory dealing with the dynamics of the lithosphere, formulated in the 1960s.  It states that Earth has a rigid outer layer, known as the lithosphere, which is about 100 km (60 miles) thick and overlies a plastic layer called the asthenosphere.  The lithosphere is broken up into about a dozen large plates and several small ones. These plates move relative to each other, typically at rates of 5 to 10 cm per year, and interact at their boundaries, where they either converge, diverge, or slip past one another.  Such interactions are responsible for most of Earth's seismic and volcanic activity. For example, plate motions cause mountains to rise where they push together or continents to fracture and oceans to form where they pull apart.
    10. 10.  Gypsum  Fossils  Salt  Glossopteris fern  Mesosaurus  Other Evidences  Lystrosaurus  SONAR (sound navigation  Cynognathus  Paleoclimactic Deposits  Glacial  Coal and ranging  Paleomagnetism  Polar reversal & polar wandering Rafting Isthmian links Island stepping stones Continental drift
    11. 11. Coal with fossilized fern Salt deposits in Dead Sea A valley glacier
    12. 12. Mesosaurus braziliensis An sonar being deployed in the ocean Restored skeleton of Cynognathus
    13. 13.  Mid-ocean ridges  Underwater system of mountain ranges  Usually has a rift or valley running along its spine  Resembles stitches on a baseball  Seafloor spreading  A hypothetical process that occurs at the mid-ocean ridges  New oceanic crust is formed through volcanic activity; slowly moving away from the ridge  Asthenosphere  A region in the Earth’s upper mantle made up of squishy, deformable rocks  Subduction zone  Zone located at convergent boundaries where a plate is subducted by another plate  Hotspot  Volcanic regions fed by magma from the mantle
    14. 14. Hotspots on the Lithosphere
    15. 15. Cross-section of some of Earth’s layers
    16. 16. THE BOUNDARIES Plates interact with each other at sites called boundaries. There are three kinds of boundaries: divergent, convergent, and transform.
    17. 17. THE BOUNDARIES • Divergent boundaries are sites where plates move away from each other. • Convergent boundaries are sites where plates move toward each other, subducting one plate in the process. • Transform boundaries are sites where plates slide past each other, creating a lot of friction in the process.
    18. 18. THE BOUNDARIES • Divergent boundaries are sites where plates move away from each other. • As plates move apart at a divergent plate boundary, the release of pressure causes partial melting of the underlying mantle. • This molten material, known as magma, is basaltic in composition and is buoyant. As a result, it wells up from below and cools close to the surface to generate new crust. • Because new crust is formed, divergent boundaries are also called constructive boundaries.
    19. 19. • Convergent boundaries are sites where plates move toward each other. • Two oceanic plates: the older, denser plate is subducted beneath the younger, warmer one. • Oceanic and continental plate: the greater buoyancy of continental crust prevents it from sinking (oceanic plate is subducted). • Continents are preserved in this manner relative to oceanic crust, which is continuously recycled into the mantle. • Two continental plates: neither is subducted; instead, towering mountain ranges, such as the Himalayas, are created.
    20. 20. • Transform boundaries are sites where plates slide past each other, creating a lot of friction in the process. • The majority of transform boundaries link segments of oceanic ridges. However, transform faults also occur between plate boundaries with continental crust—for example, the San Andreas Fault in California. • These boundaries are conservative because plate interaction occurs without creating or destroying crust. • The fault surfaces are rarely smooth, and pressure may build up when the plates on either side temporarily lock. This build-up of stress may be suddenly released in the form of an earthquake
    21. 21. Divergent Convergent Transform
    22. 22. THANK YOU FOR LISTENING! (we do hope you listened…) Content from Encyclopedia Britannica Ultimate Reference Suite 2011 and Microsoft Student with Encarta Premium 2009

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