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PLATE TECTONICS ONLINE INTERNET ACTIVITY
Welcome to the Plate Tectonics Online Internet Activity. Go to Internet Explorer and type
in the following address: http://library.thinkquest.org/18282/enter.html. This will take you
directly to the opening page of PLATE TECTONICS ONLINE)
Please read the Introduction:
Now click the button to begin the Lesson.
Label the parts on the diagram. Draw
a line to each of the parts.
Crust
Inner Core
Outer Core
Lower Mantle
Upper Mantle
Describe the three chemical layers of the earth.
Core
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Mantle
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Crust (Be sure to describe both types)
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What is the lithosphere?
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What is the asthensphere?
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Continental drift was originally proposed by Alfred Wegener, a German meteorologist, in 1912. Wegener used the fit of the
continents, the distribution of fossils, a similar sequence of rocks at numerous locations, ancient climates, and the apparent
wandering of the Earth's polar regions to support his idea. Wegener used his observations to hypothesize that all of the
present-day continents were once part of a single supercontinent called Pangaea.
How long ago were the present day continents combined into one “supercontintent”?
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For the following items explain the ideas that Wegener used in his theory.
Fossils:
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Rock Sequences:
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Glaciers:
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Climate:
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Why was Wegener’s idea not accepted by all geologists?
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Geologists have known for over a century that a ridge exists in the middle of the Atlantic Ocean. The MidAtlantic Ridge is 6,500 feet (2,000 m) above the adjacent sea floor, which is at a depth of about 20,000 feet (6,000
m) below sea level. In the 1950s, a seismologist, a scientist who specializes in the study of earthquakes, showed
that the global system of mid-ocean ridges was also an active seismic belt, or zone of earthquakes. An international
group of geologists proposed that the seismic belt corresponded to a trough, or rift, system similar to the trough
known at the crest of the Mid-Atlantic Ridge. The rifts are about 20 miles (30 km) wide and 6,500 feet (2,000 m)
deep. In all, the oceanic ridges and their rifts extend for more than 37,500 miles (60,000 km) in all the world's
oceans.
What did Harry Hess propose?
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Who proposed the model called “sea floor spreading”?
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