Presentation on theme: "Plate Boundaries--The location were two plates meet. Divergent boundaries -- where new crust is generated as the plates pull away from each other. Convergent."— Presentation transcript:
Plate Boundaries--The location were two plates meet. Divergent boundaries -- where new crust is generated as the plates pull away from each other. Convergent boundaries -- where crust is destroyed as one plate dives under another. Transform boundaries -- where crust is neither produced nor destroyed as the plates slide horizontally past each other. Plate-Boundary zones--broad belts in which boundaries are not well defined and the effects of plate interaction are unclear. Experience different plate boundaries
Oceanic-continental convergence--Where the plate that is covered by water and the plate that is covered by land meet. Oceanic-Oceanic Convergence--when two oceanic plates converge, one is usually sub ducted under the other, and in the process a trench is formed. Continental-Continental convergence-- When two continents meet head-on, neither is sub ducted because the continental rocks are relatively light and, like two colliding icebergs, resist downward motion. Instead, the crust tends to buckle and be pushed upward or sideways.
Transform Boundaries -The zone between two plates sliding horizontally past one another. -A transform boundary is said to occur when tectonic plates slide and grind against each other along a transform fault. -Concept originated by Canadian geophysicist J. Tuzo Wilson -Offset the active spreading ridges and produce zig-zag plate margins defined by shallow earthquakes. -Example is the San Andres Fault in California -Cause a lot of Earth Quakes -The Great San Francisco Earthquake of 1906
Convergent Boundaries -the location where sinking of a plate occurs is called a subduction zone -Convergence is a very slow collision of plates -There is three types of convergent boundaries Oceanic-Continental Convergence -Trenches are created by subduction -One plate is being subducted under another -One example is when the Naza Plate bumps into the South American Plate and is being subducted under. The Andes Mountains were created as the S.A. Plate rises. This causes major earthquakes
Oceanic- Oceanic Convergence -A trench is formed when one plate is subducted and two oceanic plates converge. -One example is Marianas Trench -Formed where fast Pacific Plate converges against the slower Philippine Plate -This convergence results in volcanoes. -Many volcanoes (like Hawaii) are situated on island arcs that are really trenches that was created by convergences!
Continental-Continental Convergences - Himalayan Mountain is formed by the Eurasian Plate overriding the Indian Plate 50 million years ago! -Mountain ranges like the Alps and the Rockies were formed this way. -Powerful collision -Because the density of the plates is lower than the mantle, subduction is prevented. A mountain is formed because subduction is difficult
An example of the effects of divergent boundaries is Iceland which is split in half by the Mid- Atlantic Ridge and will eventually split in half as the Ridge expands. Divergent boundaries -- where new crust is generated as the plates pull away from each other. Occurs along spreading centers were plates are moving across and new crust is being created when magna pushes up from the mantle. Example is the Mid-Atlantic Ridge-- this is a mostly underwater mountain range that runs through the Arctic and Atlantic Oceans.
HISTOICAL INFORMATION ON PLATE BOUNDARIES The scientist who began the research on Plate boundaries was Alfred Wegener. He came up with the theory that at one point in time all the continents were one. He arrived at this theory when he red a report talking about how some of the same types of plant and animal fossils were being found on opposite sided of the Atlantic ocean. He began to study the continents and noticed how they looked as if at one time they could have all fit together. Many scientists thought this was not at all a logical theory and rejected the idea all together, but eventually the idea gained more support as time went on.
REAL LIFE APPLICATIONS Plate movement cause a lot of natural disasters Plate movement can cause large cracks in the surface, earthquakes, and fissures Plate also create mountains by pushing up on each other. Volcanoes can erupt from plate movement Geodesy is the study of the size and shape of earth People study plate boundaries with geodesy Scientist can study plate boundaries on the ground but the best way is through a satellite.
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Divergent Boundary Exercise -You can simulate divergent plate motion by placing your palms down with your index fingers touch. Now pull your hands apart. Convergent Boundary Exercise -You can simulate convergent plate motion by placing your hands together in front of you with your palms down. Now gently slide your bottom hand downward and your top hand upward, while keeping them in contact. Transform Boundary Exercise -You can simulate transformational plate motion by placing your hands together in front of you with your palms down. Now slide your left hand away from you and your right hand toward you.