Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
History of geology wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Major explorations after the Age of Discovery wikipedia , lookup
Magnetotellurics wikipedia , lookup
Large igneous province wikipedia , lookup
Geomagnetic reversal wikipedia , lookup
Convection currents • The circulation of material caused by differences in temperature and density • The rice in the beaker would rise and fall with the water as it heated up and cooled off. • Convection Currents happen in the mantle and cause the molten rock/magma to circulate (rise and fall) which causes the plates to move Divergent Boundary • We moved the graham crackers apart and there was icing (mantle) left in the middle to “cool” off and become new crust • • • • When plates move AWAY from each other Happens where the seafloor spreads (mid-ocean ridge) New land (crust) forms Newest land is closest to ridge, oldest land is furthest away from ridge Convergent Boundary • Moved the graham crackers back towards each other and some of the “mantle” (icing) squished or oozed up between the 2 cracker (mountains) • Form where 2 plates Collide or Come together • Both plates are equally dense, so neither subduct (sink) they will both uplift (mountains) • Himalayas are an example Transform Boundary • We moved the graham crackers past each other causing them to grind, crunch, it caused tension they crumbled a little • Forms when 2 plates slide past each other • Earthquakes are common along these plate boundaries • An example is the San Andres fault in California Convergent- Subduction Boundary • This was our last step when we pushed one cracker under the other. • Forms when two plates collide. The denser plate (oceanic) will sink below the more buoyant (floats easier) continental crust. • Denser plate will subduct • Occurs when a continental crust meets a oceanic crust. • Volcanoes happen here at the edge of continent • An example is Mount. Ranier Earth’s Magnetism • The earth (basically) has a giant bar magnet in the middle of it. Because the earths core is made of rocks (iron-rich minerals) and metals that are magnetic. • Every few hundred to few thousand years the magnetic poles reverse. This makes the rock layers magnetic polarity change. So scientists can tell when the polarity was normal (magnetic north pointing to the north pole and magnetic south pointing the south pole) and when it was reversed. (the opposite: magnetic north pointing to the south pole) This is NORMAL polarity, because a compass will point towards Geographic North (north pole) because opposites attract SO the South Magnetic Pole (in the geographic north/north pole) will attract the compass to point North • This shows that plates are moving because at mid-ocean ridges mantle rock is coming out and being pushed away from it, so it shows the magnetic polarity Evidence Plates are Moving • Sonar • Continental Drift (Alfred Wegener) • Seafloor spreading • Volcanoes and Earthquakes • Pangaea/fossils around the world- in places they wouldn’t be able to get to unless the continents were once closer • Rock clues: similar rock formations/mountain ranges on different continents (scientists can now tell how and when rock formations were formed)