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Transcript
1) TERMS – Plate- sections of the lithosphere Tectonics- “To build”, from Greek 2) GRAND CANYON AND EARTH’S HISTORY – rocks are recorded by carbon dating and radioactive dating to show the time periods of earth history which are visible in the walls of the canyon 3a) EARTH’S AGE – 4,600,000,000 years b) DATING TECHNIQUE – measuring radioactive element decay such as potassium 4a) WHAT THREE FACTORS PUZZLED WEGENER? –* the fit of the continental shorelines * identical mountains separated by oceans * identical non-marine fossils separated by oceans b) WHAT WAS HIS SOLUTION TO THESE PUZZLES? – continents continually “drift” c) WHAT DID WEGENOR COMPARE THE MOVEMENT OF CONTINENTS TO? – the movement of Greenland ice packs. 5) HOW HIGH IS THE MID-ATLANTIC RIDGE? –1,000 to 1,200m (3,000 to 4,000ft) 6a) HOW LONG IS IT? – 60,000kms b) WHAT ACTIVITY DID HESS TALK ABOUT? – seafloor spreading 7) HOW LONG HAS IT TAKEN TO FORM THE CURRENT ATLANTIC OCEAN? – 150,000,000 TO 200,000,000years 8) IN THE LAST 4,000,000 YEARS, HOW MANY POLAR FLIPS HAVE OCCURRED? –nine 9) ON AVERAGE, HOW FAST IS THE ATLANTIC SEAFLOOR SPREADING? –2.5cm/yr 10) HOW MANY PLATES IS THE LITHOSPHERE DIVIDED INTO? –20 11) LIST THE FOUR WAYS PLATES INTERACT WITH ONE ANOTHER? -*spread apart, *grind past one another, *subduction and *collision 12) WHY IS JAPAN AN EARTHQUAKE PRONE AREA? –Japan is at the edge of the collision (subduction) zone of the Eurasian and Pacific plates 13) IN THE HIMALAYAN MTNS.WHAT HAS CAUSED MARINE FOSSILS TO BE ELEVATED 29,000FT. ABOVE SEALEVEL? – India (which is on the Indo-Australian plate) continues to collide with the Eurasian plate thereby elevating rocks and “their” fossils. 14) NAME THE FORCE THAT SUSTAINS THE MOTION OF PLATE TECTONICS? convection cells of magma--- new magma rises due to its intense heat level causing older and colder magma to be pushed out of the way and sink into the mantle where it is melted and then flows toward the centre ready to exit upward to the surface completing the cell motion. 15) HOW LONG IS THE ESTIMATED TIME FOR A UNIT OF MAGMA TO COMPLETE ONE ROTATION THROUGH THE CELL? 500,000,000years 16A) WHAT IS A “HOTSPOT”? – a plume of molten magma originating within the mantle – it is not associated with or generated by plate movements – hotspots create volcanoes and islands when magma spills onto the surface of the lithosphere – there are 120 on earth’s surface B) WHERE DOES ONE EXIST TODAY? – Hawaii 17) WHY HAVE GIGANTIC QUAKES OCCURRED IN MISSOURI, WHERE NO PLATE BOUNDARIES EXIST? – as the Appalachian mtns. erode sediment is dumped into lowlands on both sides like in phase three of our notes – weight builds up on the crust there and it begins to sag – when it drops under the force of excess weight, an earthquake is the result – old faults are the weak points in the rock structures where the movement takes place – quakes are also caused when the mountains snap upward because the rock there is lighter due to the fact less rock is present 18) MICRO PLATE TECTONICS – when small plates collide with one of the 20 main plates and “fuses” with the large plate – thus the large plate is now larger 19) GROWTH OF NORTH AMERICAN PLATE – by 25% due to micro plate tectonics 20) IN WHAT WAYS HAS PLATE TECTONICS AFFECTED THE EARTH? -*builds landforms, *influences climate, *creates rocks, *creates ecosystems, *a role in evolution THE SOUTH AMERICAN GREEN TURTLE “THE MARATHONER” (see map) HER LIFE STORY OF TRAVEL: *The South American green (female) turtles swim to a distant island (Ascension Is.) on the other side of the midAtlantic ridge to lay their eggs which has saved the species from extinction due to an absence of predators. *200,000,000 years ago Ascension Is. was a mere 25 km. off the coast of Brazil. To prevent the eggs from being eaten by predatory jaguars, the lady “marathoners” swam out to the island to lay their eggs. Ascension Is. moves away from the coast of Brazil at a rate of 2.5 cm/yr. Thus the ladies have adjusted, such that over the last 200,000,000 years they’ve learned to swim 2,500 km. All of this effort has saved the species from extinction.