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PLATE TECTONICS - Coggle Diagram
PLATE TECTONICS
Earth is generally composed of 58 crustal plates. Out of these plates, scientists have identified 15 major tectonic plates, seven or eight of which are primary plates and the others are smaller plates.
PRIMARY PLATES
African Plate
Eurasian Plate
Indo-Australian Plate
North American Plate
Pacific Plate
South American Plate
Nazca Plate (sometimes considered a primary plate instead of a secondary plate)
SECONDARY PLATES
Arabian Plate
Caribbean Plate
Cocos Plate
Indian Plate
Juan De Duca Plate
Philippine Sea Plate
Scotia Plate
Nazca Plate
TERTIARY PLATES
Are smaller parts of primary or secondary plates that have broken off and continued being broken up over time.
THE THEORY OF ISOSTACY
States that whenever equilibrium exist in Earth's surface, equal mass must underlie equal surface areas, meaning a great continental mass must be formed of lighter materials than that supposed to constitute the ocean floor
Clarence Edward Dutton is an American seismologist and geologist who proposed the term " Isostasy " in 1889.
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THE BREAK OF PANGAEA
Ortelius hypotheses remained silent for several centuries until an Austrian climatologist, Alfred Wegener, proposed Continental Drift Theory.
Pangaea existed about 240 million years ago. By about 200 million years ago, this super continent began breaking up. Over million of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continental we recognized today.
ALFRED WEGENER
In his book, The Origins of continents and oceans in 1915. Wegener expanded his theory and presented pieces of evidence that Pangaea ( meaning "all earth" has really existed during the Permian period.
Finally, Wegener studied the stratigraphy of different rocks and mountain ranges. The East Coast of South America and the west coast of Africa seem to fit together like pieces of a jigsaw puzzle, and Wegener discovered their rock layers "fit" just as clearly.
Wegener was convinced that all of Earth's continents were once part of an enormous, single landmass called Pangaea.
Wegener, trained as an astronomer, used biology, botany and geology to described Pangaea and continental drift theory.
Wegener also studied plant fossils from the frigid arctic archipelago of Svalbard, Norway. These plants were not the hardy specimens adapted to survive in the arctic climate. These fossils were of tropical plants, which are adapted to a much warmer, more humid environment.
Wegener explained that about 1,100 million years ago, there was a super continent named Rodinia, which predated Pangaea. During the late Triassic Period, Pangaea began to break up into smaller supercontinents called Laurasia and Gondwanaland.