Give an example

TYPE OF PLATE BOUNDARY = EXAMPLE:

TYPE OF PLATE BOUNDARY = EXAMPLE:

TYPE OF PLATE BOUNDARY = EXAMPLE:

3. At which of the 6 types of plate boundaries will sea floor spreading occur?

4. New oceanic crust is created due to sea floor spreading. Why then don’t the ocean basins on Earth keep getting larger and larger (an expanding Earth, which DOESN’T happen, but why)?

5. In class, construct a plate model by cutting out a rectangle in the middle of a sheet of paper. Then slide the rectangle so that the left edge represents a “divergent” boundary and the right edge “subducts” under the larger piece of paper. The top and bottom edges of the rectangle will be “transform” boundaries, resulting from the other motions. Below, sketch your model and indicate with arrows how the transform boundaries “transform” the convergent boundary into the divergent boundary.

6. On the world map at the end of this lab, draw and label the following features: the Mid Atlantic Ridge; the East Pacific Rise; the continental shelves of North America; the Nazca trench; the Cascadia trench; the Japan trench; the Middle America trench; the Puerto Rico trench; the Himalayas; the San Andreas Fault; the Andes; the Cascades; the Alps; the Río Grande Rift; the East African Rift; the Appalachian Mountains; the Gulf of Mexico, the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Mediterranean Sea.

PLATE VELOCITIES

Velocity = distance ÷ time

We can determine how fast plates are moving (plate velocities) in 2 ways. A RELATIVE plate velocity can be determined looking at the ages of the oceanic crust and its distance from the mid ocean ridge. We call this “relative motion” because both plates on either side of the mid ocean ridge are moving.

For example: 3 million year old oceanic crust is 250 km from the mid ocean ridge where it was erupted, so the relative velocity of that plate is 250 km in 3 million years.
BUT – we report plate velocities in