plate tectonics
layers of the earthAlfred Wegner had the theory that the earths continents were once connected. PANGEA!!!!
Then they splat and made other continents. He found fossils from different countries and they were the same!!!! He died trying to prove that the glaciers fit. THE CONTINENTAL DRIFT THEORY WAS BORN....
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seafloor spreadingIn the 1960’s, a scientist named Henry Hess made a discovery that would vindicate Wegner.
Using new technology, radar, he discovered that the seafloor has both trenches and mid-ocean ridges. Henry Hess proposed the sea-floor spreading theory. Hess proposed that hot, less dense material below Earth’s crust rises toward the surface at the mid-ocean ridges. Then, it flows sideways, carrying the seafloor away from the ridge in both directions. As the seafloor spreads apart at a mid-ocean ridge, new seafloor is created. The older seafloor moves away from the ridge in opposite directions. This helped explain how the crust could move—something that the continental drift hypothesis could not do. PLATE TECTONICS The Earth’s crust is divided into 12 major plates which are moved in various directions. This plate motion causes them to collide, pull apart, or scrape against each other. Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction. Plates are made of rigid lithosphere. how old is your soil?Eons -billions of years
Era - hundreds of millions of years Cenozoic -recent life Mesozoic -middle life Paleozoic -ancient life Periods -tens of millions of years; based on life forms that were abundant OR became extinct Epochs -millions of years Correlation -matching rock regions in one area to another area and helps determine sequence of events in Earth’s history PRINCIPLE OF UNIFORMITARIANISM The processes occurring on Earth today have been occurring since it formed, BUT the rate and intensity have changed PRINCIPLE OF ORIGINAL HORIZONTALITY Sedimentary rocks are deposited in nearly horizontal layers PRINCIPLE OF SUPER POSITION Oldest rocks are on the bottom, each successive layer is younger PRINCIPLE OF FAUNAL SUCCESSION Oldest fossils are in the bottom layers, successive layers are PRINCIPLE OF CROSS CUTTING RELATIONSHIPS An intrusion is younger than a rock it cuts across UNCONFORMITIES Layers get shifted up or down Layers get eroded |
types of boundaries
divergentWhere the land masses/ plates pull apart.
OCEAN-OCEAN OCEAN-LAND LAND-LAND Rift-on land Rigde-under water |
convergentwhere plates collide usually one will sub-duct/go under. When the land is not oceanic it could form mountains.
OCEAN-OCEAN OCEAN-LAND LAND-LAND |
transformWhere plates scrape across each other.
OCEAN-OCEAN OCEAN-LAND LAND-LAND |