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PLATE-TECTONICS.pptx

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The document provides an overview of several geological models that were used in the early 20th century to understand global geological features, including continental drift. It discusses the theory of contractionism, which proposed that continents separated as the Earth cooled and shrank. It also discusses permanentenism, which argued that continents have always been in largely the same positions. The land-bridge hypothesis suggested that land bridges once connected continents to explain terrestrial fossil distributions. The document examines problems with each of these early models and how they helped address questions about matching fossil distributions across continents.

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MODELS AND GLOBAL GEOLOGICAL FEATURES OF EARLY 20TH CENTURY Geanlie Carl Pronton
OBJECTIVE  Explain some of the other models that were used early in the 20th century to understand global geological features. At the end of the discussion the students will be able to;
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Theory of Contractionism  The idea that since Earth is slowly cooling, it must also be shrinking.  Oceans formed above parts of former continents that had settled downward and become submerged.  This hypothesis helped to address the dilemma of the terrestrial fossils by explaining how continents once connected could now be separated by oceans.  This hypothesis helped to address the dilemma of the terrestrial fossils by explaining how continents once connected could now be separated by oceans.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Theory of Contractionism  It came with its own set of problems. One problem was that Earth wasn’t cooling fast enough to create the necessary amount of shrinking. Another problem was the principle of isostasy which wouldn’t allow blocks of continental crust to sink in the way necessary for oceans to form in accordance with contractionist theory.  Isostasy is the state in which the force of gravity pulling the plate toward Earth’s center is balanced by the resistance of the mantle to letting the plate sink.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Permanentenism  The idea that the continents and oceans have always been generally the same as they are today. This view incorporated a mechanism for creation of mountain chains known as the geosyncline theory.  A geosyncline is a thick (potentially 1000s of metres) deposit of sediments and sedimentary rocks, typically situated along the edge of a continent, and derived from continental weathering.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Permanentenism  The idea that geosynclines developed into fold-belt mountains originated in the middle of the 19th century. It was first proposed by James Hall and later elaborated upon by Dwight Dana.  The process of converting a geosyncline into a mountain belt was believed to involve compression by forces pushing from either side, causing sedimentary layers within the geosyncline to fold up.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY There are many proponents of the geosyncline theory of mountain formation but they also had a problem of explaining the intercontinental terrestrial fossil matchups.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Land-bridge hypothesis  It is said to be that continents are once linked by land bridges permitting animals and plants including man to migrate back and forth.  One proponent of this idea was the American naturalist Ernest Ingersoll. Referring to evidence of past climate changes.
GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Land-bridge hypothesis  A problem with the land-bridge hypothesis is that there is no evidence of land bridges that could account for the fossil distribution patterns. The world’s oceans are approximately 4 km deep on average, so the underwater slopes leading up to a land bridge would have to have been at least 10s of km wide in most places, and many times that in others. Even if flooded, a land bridge of that size would still be visible in the shape of ocean-floor terrain. Isostasy would not permit such a land bridge to sink down without leaving a trace.
MID 20TH CENTURY GEOLOGICAL DVANCES, MECHANISM OF PLATE TECTONICS, PLATE MOVEMENT AND LITHOSPHERE Rizza Ripotola
OBJECTIVE  Describe the numerous geological advances made in the middle part of the 20th century that provide basis for understanding the mechanism of plate tectonics and the evidence that plates have moved and lithosphere is created and destroy. At the end of the discussion the students will be able to;
PALEOMAGNETISM When rocks form, some of the minerals that make them up can become aligned with the Earth’s magnetic field, just like a compass needle pointing to north. This happens to the mineral magnetite (Fe3O4) when it crystallizes from magma. Once the rock cools the crystals are locked in place This means that if the rock moves, the crystals can’t realign themselves, and they retain a remnant magnetism. magnetite (Fe3O4)
APPARENT POLAR WANDERING PATHS The polar wandering paths were not actually records of the pole moving, they just looked that way, so the paths are now referred to as apparent polar wandering paths (APWP). Subsequent paleomagnetic work showed that unique apparent polar wandering paths can be derived from rocks in South America, Africa, India, and Australia. Rock layers recording remnant magnetism. The red arrows represent the direction of the vertical component of Earth’s magnetic field.
BASIN GEOLOGY AND GEOGRAPHY During the 20th century, our knowledge and understanding of the ocean basins and their geology increased dramatically. Before 1900 researchers knew virtually nothing about the bathymetry (the hills and valleys of the ocean floor) and geology of the oceans. By the end of the 1960s, detailed maps of the topography of the ocean floors, a clear picture of the geology of ocean floor sediments and the solid rocks beneath them, and almost as much information about the geophysical nature of ocean rocks as of continental rocks.
• Ocean floor bathymetry (and continental topography). Inset (a): the mid-Atlantic ridge, (b): the Newfoundland continental shelf, (c): the Nazca trench adjacent to South America, and (d): the Hawaiian Island chain.
BASIN GEOLOGY AND GEOGRAPHY 1. Acoustic Depth Sounding  In deep water this is a painfully slow process and the number of soundings in the deep oceans was probably fewer than 1,000. That is roughly one depth sounding for every 350,000 square kilometers of the ocean.  The voyage of the Challenger in 1872 and the laying of trans- Atlantic cables had shown that there were mountains beneath the seas, but most geologists and oceanographers still believed that the oceans were essentially vast basins with flat bottoms, filled with thousands of meters of sediments.
BASIN GEOLOGY AND GEOGRAPHY • A ship-borne acoustic depth sounder. The instrument emits sound (black arcs) that reflects off the sea floor and returns to the surface (white arcs). The time interval between emitting the sound and detecting it on receivers on the ship is proportional to the water depth.
BASIN GEOLOGY AND GEOGRAPHY 2. Seismic Reflection Sounding  involves transmitting high-energy sound bursts and then measuring the echoes with a series of receivers called geophones towed behind a ship.  The technique is related to acoustic sounding, however, much more energy is transmitted and the sophistication of the data processing is much greater.
BASIN GEOLOGY AND GEOGRAPHY 3. Heat Flow Rates  In the early 1950s, Edward Bullard developed a probe for measuring the flow of heat from the ocean floor. Bullard and colleagues found higher than average heat-flow rates along the ridges, and lower than average rates in trenches. 4. Earthquake Belts  With developments of networks of seismographic stations in the 1950s, it became possible to plot the locations and depths of both major and minor earthquakes with great accuracy.
MAGNETIC STRIPES ON THE SEA FLOOR  In the 1950s, scientists from the Scripps Oceanographic Institute in California persuaded the United States Coast Guard to include magnetometer readings on one of their expeditions to study ocean floor topography.  Harry Hammond Hess proposed that new sea floor was generated from mantle material at the ocean ridges.  Hess’s hypotheses formed the basis for our ideas on sea-floor spreading and continental drift, but did not go so far as to claim that the crust is made up of separate plates. The Hess model was not roundly criticized, but also not widely accepted, partly because evidence was still lacking.
 Old sea floor was dragged down at the ocean trenches and re-incorporated into the mantle.  He suggested that the process was driven by mantle convection currents, rising at the ridges and descending at the trenches. He also suggested that the less-dense continental crust did not descend with oceanic crust into trenches, but that colliding landmasses were thrust up to form mountains.
SEVEN MAJOR PLATES AND TYPES OF BOUNDARIES Jonas Miranda &Twinkle Rillon
OBJECTIVE  List the seven major plates, their extents, and their general direction of motion and identify the types of boundaries between them. At the end of the discussion the students will be able to;
 Plate tectonics – is a scientific theory that explains how major landforms are created as a result of Earth’s subterranean movements. The theory, which solidified in the 1960s, transformed the earth sciences by explaining many phenomena, including mountain building events, volcanoes, and earthquakes. THE WORLD ATLAS NAME SEVEN MAJOR PLATES:
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: African plates – is a major tectonic plate straddling the equator as well as the prime meridian.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Antarctic – is a tectonic plate containing the continent of antarctica, the Kerguelen Plateau and extending outward under the surrounding oceans.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Eurasian plate – is a tectonic plate which includes most of the continent of Eurasia with the notable exceptions of the Indian subcontinent.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Indo-Australian – is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: North American Plate – The tectonic plate covering most of the north America, Cuba, the Bahamas, extreme northeastern Asia and parts of Iceland and the Azores. Earth’s second largest tectonic plate.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Pacific – is an oceanic tectonic plate that lies beneath the pacific ocean. It contains an interior hot spot forming the Hawaiian islands relative to African plate.
THE WORLD ATLAS NAME SEVEN MAJOR PLATES: South American Plate – is a major tectonic plate which includes the continent of south America as well as sizable region of Atlantic ocean seabed extending eastward to the African plate, which it forms the southern part of the mid-Atlantic ridge.
GEOLOGICAL PROCESSES THAT TAKE PLACE AT DIVERGENT AND CONVERGENT BOUNDARIES AND TRANSFORM FAULTS Daphnie June A. Palero
OBJECTIVE  Describe the geological processes that take place at divergent and convergent plate boundaries, and explain the existence of transform faults. At the end of the discussion the students will be able to;
 When two plate tectonics move away from each other they form divergent plate boundaries.  Earthquake is abundant along these fault lines and magma (molten rock) rises to the surface from the earth’s mantle, solidifying new form of oceanic crust. Divergent boundaries
 A convergent boundary is formed when two plates come together.  The impact of colliding plates can force one or both plates' edges to buckle up into mountain ranges or bend down into a deep undersea trench. Parallel to convergent plate boundaries, a chain of volcanoes often arises, and severe earthquakes are prevalent along these borders. Convergent Boundaries
 A transform fault can arise in the segment of a fracture zone that connects spreading centers to deep-sea trenches in subduction zones, or in the component of a fracture zone that exists between distinct offset spreading centers. Transform Fault
PLATE-TECTONICS.pptx
THE SUPER-CONTINENT Mangarin James Aaron
OBJECTIVE  Explain how super-continents form and how they break apart. At the end of the discussion the students will be able to;
MECHANISM OF PLATE MOVEMENT Isabel Mertola
OBJECTIVE  Describe the mechanisms for plate movement. At the end of the discussion the students will be able to;
THE MECHANISMS FOR PLATE MOVEMENT Convection Current  A convection current is a process that involves the movement of energy from one place to another. It is also called convection heat transfer.
THE MECHANISMS FOR PLATE MOVEMENT Mantle convection  Mantle convection is the very slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior to the planet's surface.  Hot materials rise because they are less dense.  Cold materials sink because the are more dense.
THE MECHANISMS FOR PLATE MOVEMENT Ridge push (also known as gravitational sliding) or sliding plate force is a proposed driving force for plate motion in plate tectonics that occurs at mid-ocean ridges as the result of the rigid lithosphere sliding down the hot, raised asthenosphere below mid-ocean ridges. At a Mid Ocean Ridge, convection cycles help push magma up and split the land apart.
THE MECHANISMS FOR PLATE MOVEMENT Slab pull  Slab pull is that part of the motion of a tectonic plate caused by its subduction. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. This force and slab suction account for almost all of the force driving plate tectonics.
PLATE-TECTONICS.pptx

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PLATE-TECTONICS.pptx

  • 1. MODELS AND GLOBAL GEOLOGICAL FEATURES OF EARLY 20TH CENTURY Geanlie Carl Pronton
  • 2. OBJECTIVE  Explain some of the other models that were used early in the 20th century to understand global geological features. At the end of the discussion the students will be able to;
  • 3. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Theory of Contractionism  The idea that since Earth is slowly cooling, it must also be shrinking.  Oceans formed above parts of former continents that had settled downward and become submerged.  This hypothesis helped to address the dilemma of the terrestrial fossils by explaining how continents once connected could now be separated by oceans.  This hypothesis helped to address the dilemma of the terrestrial fossils by explaining how continents once connected could now be separated by oceans.
  • 4. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Theory of Contractionism  It came with its own set of problems. One problem was that Earth wasn’t cooling fast enough to create the necessary amount of shrinking. Another problem was the principle of isostasy which wouldn’t allow blocks of continental crust to sink in the way necessary for oceans to form in accordance with contractionist theory.  Isostasy is the state in which the force of gravity pulling the plate toward Earth’s center is balanced by the resistance of the mantle to letting the plate sink.
  • 5. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Permanentenism  The idea that the continents and oceans have always been generally the same as they are today. This view incorporated a mechanism for creation of mountain chains known as the geosyncline theory.  A geosyncline is a thick (potentially 1000s of metres) deposit of sediments and sedimentary rocks, typically situated along the edge of a continent, and derived from continental weathering.
  • 6. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Permanentenism  The idea that geosynclines developed into fold-belt mountains originated in the middle of the 19th century. It was first proposed by James Hall and later elaborated upon by Dwight Dana.  The process of converting a geosyncline into a mountain belt was believed to involve compression by forces pushing from either side, causing sedimentary layers within the geosyncline to fold up.
  • 7. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY There are many proponents of the geosyncline theory of mountain formation but they also had a problem of explaining the intercontinental terrestrial fossil matchups.
  • 8. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Land-bridge hypothesis  It is said to be that continents are once linked by land bridges permitting animals and plants including man to migrate back and forth.  One proponent of this idea was the American naturalist Ernest Ingersoll. Referring to evidence of past climate changes.
  • 9. GLOBAL GEOLOGICAL MODELS OF EARLY 20TH CENTURY Land-bridge hypothesis  A problem with the land-bridge hypothesis is that there is no evidence of land bridges that could account for the fossil distribution patterns. The world’s oceans are approximately 4 km deep on average, so the underwater slopes leading up to a land bridge would have to have been at least 10s of km wide in most places, and many times that in others. Even if flooded, a land bridge of that size would still be visible in the shape of ocean-floor terrain. Isostasy would not permit such a land bridge to sink down without leaving a trace.
  • 10. MID 20TH CENTURY GEOLOGICAL DVANCES, MECHANISM OF PLATE TECTONICS, PLATE MOVEMENT AND LITHOSPHERE Rizza Ripotola
  • 11. OBJECTIVE  Describe the numerous geological advances made in the middle part of the 20th century that provide basis for understanding the mechanism of plate tectonics and the evidence that plates have moved and lithosphere is created and destroy. At the end of the discussion the students will be able to;
  • 12. PALEOMAGNETISM When rocks form, some of the minerals that make them up can become aligned with the Earth’s magnetic field, just like a compass needle pointing to north. This happens to the mineral magnetite (Fe3O4) when it crystallizes from magma. Once the rock cools the crystals are locked in place This means that if the rock moves, the crystals can’t realign themselves, and they retain a remnant magnetism. magnetite (Fe3O4)
  • 13. APPARENT POLAR WANDERING PATHS The polar wandering paths were not actually records of the pole moving, they just looked that way, so the paths are now referred to as apparent polar wandering paths (APWP). Subsequent paleomagnetic work showed that unique apparent polar wandering paths can be derived from rocks in South America, Africa, India, and Australia. Rock layers recording remnant magnetism. The red arrows represent the direction of the vertical component of Earth’s magnetic field.
  • 14. BASIN GEOLOGY AND GEOGRAPHY During the 20th century, our knowledge and understanding of the ocean basins and their geology increased dramatically. Before 1900 researchers knew virtually nothing about the bathymetry (the hills and valleys of the ocean floor) and geology of the oceans. By the end of the 1960s, detailed maps of the topography of the ocean floors, a clear picture of the geology of ocean floor sediments and the solid rocks beneath them, and almost as much information about the geophysical nature of ocean rocks as of continental rocks.
  • 15. • Ocean floor bathymetry (and continental topography). Inset (a): the mid-Atlantic ridge, (b): the Newfoundland continental shelf, (c): the Nazca trench adjacent to South America, and (d): the Hawaiian Island chain.
  • 16. BASIN GEOLOGY AND GEOGRAPHY 1. Acoustic Depth Sounding  In deep water this is a painfully slow process and the number of soundings in the deep oceans was probably fewer than 1,000. That is roughly one depth sounding for every 350,000 square kilometers of the ocean.  The voyage of the Challenger in 1872 and the laying of trans- Atlantic cables had shown that there were mountains beneath the seas, but most geologists and oceanographers still believed that the oceans were essentially vast basins with flat bottoms, filled with thousands of meters of sediments.
  • 17. BASIN GEOLOGY AND GEOGRAPHY • A ship-borne acoustic depth sounder. The instrument emits sound (black arcs) that reflects off the sea floor and returns to the surface (white arcs). The time interval between emitting the sound and detecting it on receivers on the ship is proportional to the water depth.
  • 18. BASIN GEOLOGY AND GEOGRAPHY 2. Seismic Reflection Sounding  involves transmitting high-energy sound bursts and then measuring the echoes with a series of receivers called geophones towed behind a ship.  The technique is related to acoustic sounding, however, much more energy is transmitted and the sophistication of the data processing is much greater.
  • 19. BASIN GEOLOGY AND GEOGRAPHY 3. Heat Flow Rates  In the early 1950s, Edward Bullard developed a probe for measuring the flow of heat from the ocean floor. Bullard and colleagues found higher than average heat-flow rates along the ridges, and lower than average rates in trenches. 4. Earthquake Belts  With developments of networks of seismographic stations in the 1950s, it became possible to plot the locations and depths of both major and minor earthquakes with great accuracy.
  • 20. MAGNETIC STRIPES ON THE SEA FLOOR  In the 1950s, scientists from the Scripps Oceanographic Institute in California persuaded the United States Coast Guard to include magnetometer readings on one of their expeditions to study ocean floor topography.  Harry Hammond Hess proposed that new sea floor was generated from mantle material at the ocean ridges.  Hess’s hypotheses formed the basis for our ideas on sea-floor spreading and continental drift, but did not go so far as to claim that the crust is made up of separate plates. The Hess model was not roundly criticized, but also not widely accepted, partly because evidence was still lacking.
  • 21.  Old sea floor was dragged down at the ocean trenches and re-incorporated into the mantle.  He suggested that the process was driven by mantle convection currents, rising at the ridges and descending at the trenches. He also suggested that the less-dense continental crust did not descend with oceanic crust into trenches, but that colliding landmasses were thrust up to form mountains.
  • 22. SEVEN MAJOR PLATES AND TYPES OF BOUNDARIES Jonas Miranda &Twinkle Rillon
  • 23. OBJECTIVE  List the seven major plates, their extents, and their general direction of motion and identify the types of boundaries between them. At the end of the discussion the students will be able to;
  • 24.  Plate tectonics – is a scientific theory that explains how major landforms are created as a result of Earth’s subterranean movements. The theory, which solidified in the 1960s, transformed the earth sciences by explaining many phenomena, including mountain building events, volcanoes, and earthquakes. THE WORLD ATLAS NAME SEVEN MAJOR PLATES:
  • 25. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: African plates – is a major tectonic plate straddling the equator as well as the prime meridian.
  • 26. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Antarctic – is a tectonic plate containing the continent of antarctica, the Kerguelen Plateau and extending outward under the surrounding oceans.
  • 27. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Eurasian plate – is a tectonic plate which includes most of the continent of Eurasia with the notable exceptions of the Indian subcontinent.
  • 28. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Indo-Australian – is a major tectonic plate that includes the continent of Australia and surrounding ocean, and extends northwest to include the Indian subcontinent and adjacent waters.
  • 29. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: North American Plate – The tectonic plate covering most of the north America, Cuba, the Bahamas, extreme northeastern Asia and parts of Iceland and the Azores. Earth’s second largest tectonic plate.
  • 30. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: Pacific – is an oceanic tectonic plate that lies beneath the pacific ocean. It contains an interior hot spot forming the Hawaiian islands relative to African plate.
  • 31. THE WORLD ATLAS NAME SEVEN MAJOR PLATES: South American Plate – is a major tectonic plate which includes the continent of south America as well as sizable region of Atlantic ocean seabed extending eastward to the African plate, which it forms the southern part of the mid-Atlantic ridge.
  • 32. GEOLOGICAL PROCESSES THAT TAKE PLACE AT DIVERGENT AND CONVERGENT BOUNDARIES AND TRANSFORM FAULTS Daphnie June A. Palero
  • 33. OBJECTIVE  Describe the geological processes that take place at divergent and convergent plate boundaries, and explain the existence of transform faults. At the end of the discussion the students will be able to;
  • 34.  When two plate tectonics move away from each other they form divergent plate boundaries.  Earthquake is abundant along these fault lines and magma (molten rock) rises to the surface from the earth’s mantle, solidifying new form of oceanic crust. Divergent boundaries
  • 35.  A convergent boundary is formed when two plates come together.  The impact of colliding plates can force one or both plates' edges to buckle up into mountain ranges or bend down into a deep undersea trench. Parallel to convergent plate boundaries, a chain of volcanoes often arises, and severe earthquakes are prevalent along these borders. Convergent Boundaries
  • 36.  A transform fault can arise in the segment of a fracture zone that connects spreading centers to deep-sea trenches in subduction zones, or in the component of a fracture zone that exists between distinct offset spreading centers. Transform Fault
  • 39. OBJECTIVE  Explain how super-continents form and how they break apart. At the end of the discussion the students will be able to;
  • 41. OBJECTIVE  Describe the mechanisms for plate movement. At the end of the discussion the students will be able to;
  • 42. THE MECHANISMS FOR PLATE MOVEMENT Convection Current  A convection current is a process that involves the movement of energy from one place to another. It is also called convection heat transfer.
  • 43. THE MECHANISMS FOR PLATE MOVEMENT Mantle convection  Mantle convection is the very slow creeping motion of Earth's solid silicate mantle caused by convection currents carrying heat from the interior to the planet's surface.  Hot materials rise because they are less dense.  Cold materials sink because the are more dense.
  • 44. THE MECHANISMS FOR PLATE MOVEMENT Ridge push (also known as gravitational sliding) or sliding plate force is a proposed driving force for plate motion in plate tectonics that occurs at mid-ocean ridges as the result of the rigid lithosphere sliding down the hot, raised asthenosphere below mid-ocean ridges. At a Mid Ocean Ridge, convection cycles help push magma up and split the land apart.
  • 45. THE MECHANISMS FOR PLATE MOVEMENT Slab pull  Slab pull is that part of the motion of a tectonic plate caused by its subduction. Plate motion is partly driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches. This force and slab suction account for almost all of the force driving plate tectonics.