Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download PLATE TECTONICS
Document related concepts
Transcript
PLATE TECTONICS GEOLOGY Chapter 16 JAMES HUTTON 1727-1797 Father of Geology Edinburgh, Scotland Doctor of Medicine then became a farmer Can you believe he never married? Before Hutton there was no Geology as a science Influenced Charles Darwin Claim to Fame Earth is older than 6,000years! Not all rocks were deposited in the “Great Flood” – Not all sedimentary or flat! UNIFORMITARIANISM- present is the key to the past – Basis of geology today ALFRED WEGENER Father of Plate Tectonics 1880-1930 PLATE TECTONICS Born in Germany Greenland meteorologist Originated “radical” continental drift theory CREDENTIALS Ph.D. in astronomy Ph.D in meteorology (U of Berlin) polar atmosphere researcher published –Origin of Continents and Oceans (1915) EVIDENCE FOR “CONTINENTAL DRIFT” Shapes of continents- fit together Identical fossils separated by oceans Same rock layers match across continents Glacial evidence in tropics No one believed him- why not? Didn’t know what caused the plates to move tidal force? Plates “plowed” through ocean crust- ocean floor is not weak! Last photo of Wegner Died lost in Greenland- 1930 Ridiculed by scientist NEW (post Wegner)EVIDENCE 1. Sonar (1960’s)- mapped ocean floor – each side of mid-ocean ridges match up • Age of rock • paleomagnetism More “new” evidence 2. Pattern of earthquakes- outline edges of plates Maybe Wegner was right! “New” theory (1968) called PLATE TECTONIC THEORY Included: – “new” way plates move – “new” ocean evidence How do plates move? Theory one- convection currents Hot magma rises and cold magma sinks creating a current Heat comes from radioactivity Plates “ride” on this current Convection currents How do plates move? Theory 2- Slab pull/ridge push – Plates pull themselves down due to density How do plates move? UNSURE! – Combo of both? – Wasn’t this the same problem Wegner had? What is a plate? Plate tectonics explains so much! Location of… – Volcanoes – Earthquakes – Igneous rocks – Metamorphic rocks – Mountains – Folds and faults PLATE BOUNDARIES Where plates meet DIVERGENT Move apart tensional stress fissure eruptions basalt most under the sea- Mid Ocean Ridge some continental- East African rift, Red Sea,Yellowstone Divergent boundaries Fissure eruption CONVERGENT BOUNDARIES Move together compressional stress 3 types Ocean-ocean Volcanoes form on ocean floor- create island arcs Trenches andesite Japan Ocean-continental Trenches (not as deep) composite volcanoes- pumice, rhyolite Volcanoes form on land Mt. St. Helens Continental-continental Folded mountains- non-volcanic! Metamorphic rock Himalayas Mt. Everest TRANSFORM(strike-slip) Plates slide past each other shearing stress shallow earthquakes San Andreas Fault Passive Plate boundaries Non- active ocean/ cont. boundary Who gives a schist? Predict earthquake areas Source for geothermal energy Find areas of mineral resources Predict future?
