acloutier copyright 2013Continental Driftfrom a Hypothesis by Alfred Wegener and wasdeveloped into a Theory with supporting evidence Super continent called Pangaea >Greek for “all land” Began to brake apart over 200 million years ago Puzzle fit of South America and Africa Collected evidence in rocks, fossils, and climatic data tosupport his hypothesis
acloutier copyright 2013Evidence to collect to support hypothesis but, no means toexplain how the continents were moved…yet !
acloutier copyright 2013Glossopteris and Mesosaurus
acloutier copyright 2013Ancient climatesevidence of coal deposits found in Antarctica coal is formed from swamp plant or other vegetation thathas decomposed this meant a temperate rainy climate was once on thesurface of Antarctica glacial deposits of till and striation scratches on bedrockfound in Afrrica, 290 million year old land formations today Africa is covered by huge deserts where theevidence of continental glaciers was documented
acloutier copyright 2013Seafloor Spreading Technology sonar echo-location > sound beams /time returned WWII submarine warfaredeveloped technology todetect more than anenemy sub Detailed maps and a safeway to navigate thebottom
acloutier copyright 2013Seafloor spreading Harry Hess
acloutier copyright 2013Mid Ocean Ridges & Trenches Ocean ridges are longmountain ranges Continuous wrap aroundplanet Deepest and longestmountain range on theplanet ~46,000 miles long (~ 72km) Mariana Trench 11 km deep deepesttrench in all oceans
acloutier copyright 2013Continental Crust - Oceanic Crust Oldest age 3.8 BYBP Billions of years beforepresent Less dense than oceaniccrust Continental mountainskeep getting folded andfaults break up crust Young age ~ today’s lava>180 MYBP Millions of years beforepresent More dense thancontinental crust The further away from theridge the thicker andolder the oceanic crustbecomes
acloutier copyright 2013Earth quakes occur at plate boundaries
acloutier copyright 2013Causes of Plate Movement Mantle convection are thought to be the driving mechanism of plate tectonicmovement(continental drift caused by seafloor spreading and subduction) The transfer of heat, called thermal energy is the cause of the movement ofhot matter (magma) moving to cold matter; this is called convection Warm matter move toward cold matter Cooler matter sinks because it is more dense “G force” gravity pulls it down into the mantle Ridge push and slab pull are the results of this process of heat moving awayfrom the radiation of the core out towards the crust
acloutier copyright 2013Convection current of Earth’s mantlethe bulldozer pushes plates around the planet surface
acloutier copyright 2013Isochron Mapmaps with magnetic fields showing Earth’s polarity formagnetic north A line graph defined by datafor rocks of the same age; With the same isotopiccomposition Polarity event is recorded inrocks a period of no morethan 100,000 years whenEarth’s magnetic polarity wasopposite to the existingpolarity
acloutier copyright 2013Check out and watch this movie on your iPad http://science.discovery.com/tv-shows/greatest-discoveries/videos/100-greatest-discoveries-magnetic-field-reversal.htm
acloutier copyright 2013Questions?Going further time for the iPad technology Do scientist know if convection currents stay inthe same places ? Are hot spots located in the same places ?For how long ? Is Cape Cod located on a hot spot? What state is located over a hot spot ? When was the last earthquake Cape Cod felt ?