plate tectonics & boundaries. key terms 1.diverging 2.converging 3.transform 4.fault 5.tectonic...
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Plate Tectonics & Boundaries
Key Terms
1. diverging
2. converging
3. transform
4. fault
5. tectonic plate
• Moving apart• Moving together• Sliding past• A break or crack in the Earth’s
crust• a rigid layer of the Earth's
lithosphere that is believed to drift slowly
Key Terms6. Lithosphere
7. Asthenosphere
8. convection
9. subduction
10. topography
• Earth’s layer with crust and upper mantle
• Earth’s layer with slowly flowing mantle rock that allows tectonic plates to move
• Currents caused by rising hot matter, and sinking cooler matter
• process in which one edge of a crustal plate is forced downward into the mantle below another plate
• The shape and features of the surface of land
From studying
maps, people noticed that
the continents
appeared as if they fit
together like a giant jigsaw puzzle.
Because of this, a scientist named Alfred Wegener, hypothesized that the continents once formed a
single landmass called a supercontinent. This was later called Pangaea.
Evidence #1:Similar Plant & Critter Fossils
Evidence #2:
Rock Formations of nearly identical rocks and structures
Evidence #3:
Similar climatic pasts
Beginning of the Theory
• Scientists (meteorologist) who proposed the Theory of Continental Drift, but did not know why the continents moved -- Alfred Wegener.
• Evidence he had:– Shape of continents– Similar plant and animal fossils– Similar rock formations– Similar climatic pasts with
glacier evidence in warm areas and tropical evidence in cold areas
…but this was not enough evidence to
convince the world of continental drift.
Beginning of the Theory
• The main reason other scientists did not agree with, or believe, this theory was because Wegener could not come up with a mechanism or reason why the continents could move.
• Wegener called the original land form Pangaea.
Sea Floor Mapping
Beginning of Evidence
• The scientist (geologist) Harry Hess discovered the mid-Atlantic ridge.
• Harry Hess had discovered that the sea floor is spreading and new earth is being generated at the crack.
• He also appreciated the fact that somewhere else in the world earth must also be being destroyed.
HARRY HESS
• Captain of the assault transport USS Cape Johnson
1-Heat from the light bulb heats the globs of wax, making them less dense.
•The heated wax rises.
2-Wax further away from the heat source cools and becomes more dense.
•The cooled wax sinks.
3-This process is known as convection.
Mantle Convection
VERY HOT CORE heats magma, causing it to RISE
COOLING caused by melting of crust causes mantle to SINK
VERY HOT COREHOT MAGMA
RISES(heated by core)
Plate Plate
Diverging Boundaries
Diverging Plates - #1
• Name: Rift• Type of Crust:
Ocean/Ocean• Movement: Pulling Apart• Geography: mountains and rift• Locations: Mid-Ocean Atlantic Ridge
Diverging Plates #2
• Name: Normal Fault• Type of Crust:
Continental/Continental
• Movement: Pulling Apart
• Geography: Valleys, Lakes
• Locations: Great Salt Lake, African Rift Valley, Death Valley
VERY HOT CORE
COOLER, MELTING LAVA
SINKS
plateplate
Converging Boundaries
Converging Plates #1• Name: Folded Fault• Type of Crust: Continental / Continental• Movement: Pushing Together• Geography: Mountains, Hills, Folded Rock• Location: Jura Mountains (Switzerland), Himalayans
(Mt. Everest)
Converging Plates #2
• Name: Subduction Fault
• Type of Crust: Ocean/Ocean
• Movement: Pushing together
• Geography: Trench, Volcanic Arc, Island
• Locations: Caribbean, Aleutian Islands
Converging Plates #3
• Name: Subduction Fault• Type of Crust:
Ocean/Continental• Movement: Pushing
Together• Geography: Mountain
Ranges, Volcanoes, ocean trench
• Locations: Cascade Mountains (Mt. St. Helens), Ring of Fire, Pompeii
Transform Boundary
• Name: Transform or Strike-Slip
• Type of Crust –ANY• Movement: Sliding Past• Geography: Shifted land,
cracks• Locations: San Andreas
Fault, Dead Sea
MAJOR PLATES