Presentation on theme: "Getting an A in Science Taking ownership or control of the information learned in class and taking responsibility for your work –This means: Practicing."— Presentation transcript:
Getting an A in Science Taking ownership or control of the information learned in class and taking responsibility for your work –This means: Practicing (reviewing, restating, preparing) Applying (creating, thinking, using) Planning (studying, completing projects and homework, being prepared-pencils, books)
Over time, the continents drifted (moved) apart – Wegener named his theory “Continental Drift”. Describe it
He supported his theory with four pieces of evidence.
Matching fossils of animals on once connected land areas. 1. Animal Fossil Clues
2. Plant Fossil Clues Fossils of the plant Glossopteris are found in rocks in South Africa, India, Australia, South America, and Antarctica
3. Climate Clues Glacial evidence in Africa, South America, Australia Fossils found in Antarctic soil indicate that the now frigid continent was once lush with trees and ferns, and home to dinosaurs, amphibians, and later, marsupials.
4. Rock Clues - similarities and ages Mountains in South America and Antarctica are believed to have formed as part of the same mountain chain.
Wegener’s theory made sense, but no one wanted to accept it until they knew HOW the continents moved.
Years later someone came up with an explanation of HOW the continents moved
Seafloor Spreading Who? –Harry Hess (A Princeton University scientist) When? – 1960’s
Using new technology, they looked at the ocean floor Hess and other scientists mapped the ocean floor using sonar They detected underwater mountain ranges
Further examination of the ocean floor with a submarine showed underwater volcanoes. A variety of life living near the warm vents of the volcanoes was found
Sampling the rocks near the volcanoes revealed that there was a pattern to their formation.
Describe Seafloor Spreading Magma in the mantle rises and pushes the plates apart, forming new oceanic crust. http://www.absorblearning.com/media/item.action?quick=12n http://education.sdsc.edu/optiputer/flash/seafloorspread.htm
Seafloor Spreading causes Continental Drift Now we could explain HOW the continents moved:
He supported his theory with two pieces of evidence.
1. Rock ages Youngest rocks are found at the mid-ocean ridges and they become increasingly older farther from the edges.
2. Magnetic Clues Magnetic iron particles record the time of the rock formation. When the magnetic north pole switched places, iron in the rocks recorded this information http://www.youtube.com/watch?v=BCzCmldiaWQ http://www.absorblearning.com/media/attachment.action?quick=12w&at t=2789
A map of the ocean floor provides even more evidence http://maps.google.com/ http://maps.google.com/
Iceland shows seafloor spreading above the water, which makes it easier to study
Convergent Boundary When two continental plates move into each other, the plates combine and form mountains. (India into Asia) http://www.classzone.com/books/earth_science/terc/content/visualizations/es1105/es1105page01.cfm?chapter_no=visualization http://www.absorblearning.c om/media/attachment.action ?quick=12t&att=2783
Convergent Boundary When an oceanic plate runs into a continental plate, the heavier oceanic plate subducts (sinks) into the mantle and melts back into magma.
Volcanic mountains and deep sea trenches are created along this edge. http://www. absorblearn ing.com/me dia/attachm ent.action? quick=12s &att=2781
Oceanic plate into continental Example: Pacific plate (oceanic) subducts (sinks) under Japan (continental). http://maps.google.com/ http://maps.google.com/
When both diverging plates are oceanic, it is called seafloor spreading (Mid-Atlantic Ridge)
When both diverging plates are continental it is called rift valley formation (Africa) http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0072402466/30425/19_21.swf::Fig.%2019.21% 20-%20Evolution%20of%20a%20Divergent%20Plate%20Boundary
Transform Boundary Plates slide past each other
San Andreas Fault, CA Each time the plates slide past each other, an earthquake occurs
Find the three boundaries http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave.html
Asthenosphere A plastic-like layer found below the lithosphere. The rigid oceanic and continental plates of the lithosphere sit on top
The Asthenosphere is heated by the hot Outer Core
Convection Current Hot material rises, cooler material sinks, creating a current, called a Convection Current core mantle crust
When the asthenosphere moves, it carries the lithospheric plates Convection currents cause plate motion http://www.absorblearning.com/media/attachment.action?quick=12p&att=2775 http://www.youtube.com/watch?v=ryrXAGY1dmE http://www.youtube.com/ watch?v=Kpoko_l34ZE http://www.yout ube.com/watch? v=lJiAUvB1vE U
Every time these plates move we get earthquakes, volcanic eruptions, and possibly tsunamis