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Plate Tectonics. Oliver and Grace. Alfred Wegener. If you look at a map, Africa seems to snuggle nicely into the east coast of South America and the Caribbean sea. Also, the same fossils have been found in both Africa and South America.
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Plate Tectonics Oliver and Grace
Alfred Wegener • If you look at a map, Africa seems to snuggle nicely into the east coast of South America and the Caribbean sea. Also, the same fossils have been found in both Africa and South America. • In 1912 a German Scientist called Alfred Wegener proposed that these two continents were once joined together then somehow drifted apart. • He proposed that all the continents were once stuck together as one big land mass called Pangea. • He believed that Pangea was intact until about 200 million years ago.
Types of Plate Boundaries • Transform boundaries occur where plates slide or grind past each other along transform faults. The San Andreas Fault in California is an example of a transform boundary. 1
Types of Plate Boundaries • Divergent boundaries occur where two plates slide apart from each other. Mid-ocean ridges (e.g., Mid-Atlantic Ridge) is an example of divergent boundaries. 2
Types of Plate Boundaries • Convergent boundaries (or active margins) occur where two plates slide towards each other commonly forming a subduction zone (if one plate moves underneath the other) or a continental collision (if the two plates contain continental crust). Deep marine trenches are typically associated with subduction zones. Examples of this are the Andes mountain range in South America and the Japanese island arc. 3
Types of Volcano • Composite volcanoes, also called Strato volcanoes, are formed by alternating layers of lava and rock fragments. • Shield volcanoes are huge in size. They are built by many layers of runny lava flows. Lava spills out of a central vent or group of vents. A broad shaped, gently sloping cone is formed. This is caused by the very fluid, basaltic lava which can't be piled up into steep mounds.
Earthquakes • An earthquake (also known as a quake, tremor, or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph