Download Continental Drift and Plate Tectonics Virtual Lab http://earthguide

Continental Drift and Plate Tectonics Virtual Lab
http://earthguide.ucsd.edu/eoc/teachers/t_tectonics/t_tectonics.html
Directions: Click on the box shown to the left, then use that page to fill in the information to the right.
1. Watch the animation and use the arrows to click forward and back. mybp= million years before present.
Click the arrows to move forward to 65 mybp. This is when the dinosaurs went extinct. Sketch the
outline of the continents as they appeared when the dinosaurs went extinct.
What the
Earth looked
like in the
distance past
Click forward to 0.05 mybp. What is the main difference you see on the map from 0.05 mybp
to present day?
__________________________________________________________________________________
2. What is plate tectonics?
The concept that describes and explains how the major features of the Earth _______________ and/or
deform. The essential processes of plate tectonics are:
A) ______________________________________________________________________________
Plate
Tectonics
B) ______________________________________________________________________________
Click on one of the larger color versions of the map. Notice the lighter areas, showing the underwater
mountain ranges (mid-ocean ridges) of Earth.
3. How do scientists make detailed maps of the seafloor? They use variations of a method called “sonar.”
Sonar involves _______________________________ , the same method used by bats to navigate at
night. Click “GO.” Use the tabs at the bottom to click through the rest of the animation.
Imaging
the shape
of the sea
floor
The Basics
1) Sonar Basics
Sonar works by measuring the time it takes for sound to _____________________ off of a surface
like the sea floor and return as an echo. The longer it takes for an echo to return, the farther
___________________ the reflective surface, whether it’s the far wall of a canyon or the sea floor.
2) The Actual Depth
Sound waves travel at about __________ meters per second in seawater, so a _____ second
round trip covers ~6,000 meters. However, the actual water depth is only half of that- 3,000 meters,
because 4 seconds represents ________________ the one way distance to the sea floor.
3) What do you do with sonar data?
After all the data are collected, processed, and _________________, scientists can now visualize
the ________________________.
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Feel free to click through the other tabs to learn more about different types of sonar technology.
4. Study the animation. How fast are the plates moving apart?___________________________________
Add arrows to the diagram below to show how the tectonic plates are moving.
Seafloor
spreading
(Key Process
#1)
Key Points
A) Seafloor spreading takes place at mid-ocean ridges and produces ______________________, the
rock that makes up oceanic crust.
B) The _______________________________ Ridge and East ________________________ Rise
are examples of mid-ocean ridges.
C) Mid-ocean ridges reach a typical summit of __________ meters below sea level.
D) Seafloor spreading produces major characteristics of the seafloor:
1) The age of the seafloor is progressively ____________________ away from mid-ocean ridges.
2) The elevation of the seafloor is progressively lower away from mid-ocean ridges.
3) The magnetic history of the seafloor bears the ____________________ pattern of the Earth’s
magnetic reversals.
4) _________________________ parts of the seafloor have the greatest potential to have
accumulated sediments over the longest time.
5. Study the animation. Turn the labels on and read them.
Subduction
(Key
Process #2)
Key Points
A) Subduction is a geological process in which the edge of a lithospheric plate slides
______________________ the edge of an adjacent plate.
B) Trenches, accretionary wedges (prisms), and volcanic or _________________ arcs are key
surface features produced by subduction.
C) A subduction zone is the entire ________________ of subduction between the trench and the
volcanic arc.
D) The __________________________ marks the line where subduction begins.
E) What is an accretionary wedge?
______________________________________________________________________________
______________________________________________________________________________
p. 115