Plate Tectonics Theory PDF

PLATE TECTONIC and CONTINENTAL DRIFT THEORIES  LEARNING OBJECTIVES AS A LEARNER I CAN; Explain how the seafloor spreads Describe the structure and evolution of ocean basins Explain how the movement of plates lead to new landformations  ESSENTIAL QUESTION How are the in...

PLATE TECTONIC and CONTINENTAL DRIFT THEORIES  LEARNING OBJECTIVES AS A LEARNER I CAN; Explain how the seafloor spreads Describe the structure and evolution of ocean basins Explain how the movement of plates lead to new landformations  ESSENTIAL QUESTION How are the internal layers of the Earth different from each other?  PLATE TECTONIC THEORY It is the scientific theory which states that several large tectonic plates that make up Earth's lithosphere have been moving slowly for approximately 3.4 billion years. The model is based on the theory of continental drift, which was established in the early 1900s.  INTERCONTINENTAL LAND BRIDGES EDUARD SUESS (1831-1914), an Austrian geologist and alpine geography expert stated that continents were once connected by land brides. These land bridges all connect to one big continent called GONDWANALAND.  CONTINENTAL DRIFT THEORY ALFRED LOTHAR WEGENER (1880-1930), a German meterologist postulated that all of the 7 continents were once connected to a single supercontinent called PANGEA. Due to the constant land deformation the continents were broken apart and drifted away from each other.  EVIDENCES SUPPORTING THE THEORY Wegener authored a book titled The Origin of Continents and Oceans in 1912.Here he presented evidences that would suppor this theory. The evidences Wegener used was not created by his own but was created whilst utilizing other scientific documents and studies.  EVIDENCES SUPPORTING THE THEORY One evidence are FOSSIL RECORDS, in order to support his claim, Wegener researched and found that there are fossils of the Mesosaurus found in America and Africa. These continents are highly far apart and the Mesosaurus are freshwater therefore they cannot travel across saltwater  EVIDENCES SUPPORTING THE THEORY Another evidence stated by Wegener were geologic formations. Identical formations were found among the continents, mountain ranges of one continent seemed to be the end or start of a continuation of another formation on another continent.  WHY WAS WEGENER'S THEORY REJECTED? Alfred Wegener's theory was rejected by many of his contemporaries due to his inability to formulate and identify a scientific mechanism that can thoroughly and factually explain how the continents changed their position. PANGEA: LAURASIA AND GONDWANA THEORY In the year 1937, Alexander du Toit (1878-1948), a South African geologist, gathered evidence to further support and solidify Wegener's theory. du Toit's theory stated that there were 2 supercontinents called LAURASIA and GONDWANA. These 2 then collided and formed a much larger supercontinent  SEAFLOOR SPREADING Harry Hammond Hess (1906-1969), postulated his theory on seafloor spreading. This hypothesis states that new oceanic crust is generated through the upwelling of the mantle, this phenomena happens when the oceanic crust move due to the presence of a large thermal convection current.  SEAFLOOR SPREADING This theory was then further questioned that if the seafloor is spreading then the size of the Earth should also be expanding. However, in this case the Earth is still the same size. But to counter this flaw, the process of subduction zones recycles the old crust for the new crust.