Plate Tectonics(1)

Plate Tectonics(1) - Plate Tectonics Tectonic Cycle...

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Plate Tectonics
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Tectonic Cycle Tectonic processes – large-scale movements and deformation of our crust Means ‘building’ or ‘construction’ (from Greek word tektonikus) Result of internal , or endogenic forces
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Plate Tectonics What is plate tectonics? The Tectonic Cycle is the portion of the geologic cycle that includes continental drift, sea-floor spreading, and related crustal movements….
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Plate Tectonics Plate tectonic processes include: Crustal plate movements (like continental drift ) Subduction Upwelling of magma warping, folding, and faulting of crust. Earthquakes Volcanic activity
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Plate Tectonics In this lecture, we will look at crustal plate movements. ... Continental drift Sea-floor spreading, creation of new crust Subduction (of crust) Earthquakes and volcanoes (more next week) Hot spots
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Continental Drift Have you noticed that some of the continental landmasses seem to have matching shapes-like puzzle pieces?
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Continental Drift The continents used to fit together! Have migrated to their present locations They still continue to drift (up to 6 cm a year)… We call this motion continental drift Convection currents in the asthenosphere and upper mantle move them around.
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History Continental drift was not accepted until the twentieth century As early as 1596 observers noticed coastline symmetry (the ‘puzzle-piece observation’ we just mentioned) However, a reason for the symmetry of coastlines wasn’t proposed until 1912!
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History Alfred Wegener (German geophysicist and meteorologist) proposed the idea that continents migrate or ‘drift’ in 1912 Was completely rejected at the time…. b/c before then scientists thought that continents formed 3 bya and stayed in place
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History Wegener thought that: All landmasses were originally a single supercontinent (~ 225 mya) Called ‘ Pangaea’ = ‘all earth’
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History How to figure out how continents fit together? Studied other research such as… Geologist record Fossil record Climatic record for continents Researchers concluded that South America and Africa were related in several ways. . This can be observed today through past information- such as the fossil record and the geologic record!
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South America and Africa Similar fossil remains of plants and animals on different present-day continents! Glossopteris (ancient fern, southern continents) Cynognathus (land reptile, South America and Africa) Mesosaurus (water reptile, South America and Africa)
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Fossil Record Similar fossil remains of plants and animals on different present-day continents! Examples?
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Coal Coal is created from the remains of plants that existed 100-400 million years ago… Coal deposits represent past plant growth. There are large midlatitude coal deposits (from N
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Plate Tectonics(1) - Plate Tectonics Tectonic Cycle...

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