Download Plate Tectonics Simulation Assignment

Plate Tectonics Simulation Assignment:
Background:
Alfred Wegener based his theory of continental drift on a varied collection of evidence that
showed striking similarities between continents separated by vast distances. Wegener's theory
began with his and others' observations that the coastlines of continents on opposite sides of the
Atlantic appear as if they would fit neatly against each other like the pieces of a puzzle. Wegener
bolstered his theory between 1912 and his death in 1930 with fossil evidence that showed that
the same species of plants and animals had existed in both South America and Africa. He also
noted the occurrence of fossils and rock types in North America that matched those in Europe,
and in Madagascar that matched those in India. In addition, coal deposits from tropical plants on
Arctic islands supported the idea that northern continents had once occupied tropical latitudes.
As interesting as Wegener's evidence was, fossil and geological records said nothing about the
mechanism that might have moved continents across Earth's surface. In 1928, two years before
Wegener's death, Arthur Holmes, one of the few proponents of the theory of continental drift,
proposed such a mechanism. Holmes proposed that circular convection currents of molten
material deep within Earth might provide ample force to divide and move continents. This idea
received little attention when Holmes proposed it, but 30 years later scientists found evidence
that suggested his theory was correct all along.
By the late 1960s, scientists had developed the theory of plate tectonics based on a range of new
evidence. Technological advances had helped reveal that the ocean floor was not essentially flat,
as once assumed, but instead was marked by 50,000-kilometer-long (31,000-mile), 3,000-meterhigh (9,800-ft) ridges and 11-kilometer-deep (7-mile) trenches. Scientists found striking patterns
related to these features. They found that the youngest oceanic crust is located nearest the midocean ridge and the oldest crust is nearest the trenches. They also detected a pattern of
alternating magnetic polarity along the ocean floor, which emanated from the ridge tops. These
two pieces of evidence, coupled with the fact that volcanic activity and island-building occurred
most commonly at ocean trenches, suggested that new crust was created at mid-ocean ridges and
destroyed at ocean trenches. Scientists Harry Hess and Robert Dietz used this evidence to revive
and expand Holmes' convection theory into the theory they called "seafloor spreading." Finally,
Wegener's notion of continental drift was coupled with a mechanism that could explain the
movement of tectonic plates.
Today, geologists identify three types of boundaries that occur between tectonic plates. The first,
called a divergent boundary, occurs most often at mid-oceanic ridges. Here, two plates move
away from each other, creating a break, or rift, in Earth's crust. Magma from the mantle rises to
fill the gap, thus creating new crust. The second type, called a convergent boundary, occurs when
two plates moving toward each other meet. If at least one of the plates is made up of relatively
dense oceanic crust, the denser of the two plates subducts, or slides beneath the other. If both
plates are made up of continental crust, very little subduction occurs. Instead, the plates buckle
and fold to create valleys, ridges, and high mountain ranges such as the Himalayas. The last type
is called a transform boundary. At these locations, plates slide roughly alongside each other in
opposite directions. The plates often get stuck as they move past each other, leading to a build-up
of tension. This tension is ultimately released in the form of an earthquake.
Simulation Instructions and Questions:
Go to the Plate Tectonics Introduction Video:
https://unctv.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.plateintro/platetectonics-an-introduction/
Watch the video and answer these questions:

Is Earth's surface stable and stationary now? Was it ever in the past? Do you
think it will be stable in the future?

Do you think that the way continents fit together is convincing evidence for the
theory of plate tectonics? Why or why not?

What was the supercontinent called that once contained nearly all of the
continental crust? Research what the name means.

Which ocean is growing in size? Which is shrinking? Explain why this is
occurring.

How does the theory of plate tectonics help us explain natural phenomena such
as earthquakes and mountains, which geologists had difficulty accounting for
prior to the development of the theory?
Go to the Tectonics Plates and Boundaries simulation:
https://unctv.pbslearningmedia.org/asset/ess05_int_boundaries/
Try changing all of the types of plate boundaries and tectonic plates.
Which plates have convergent boundaries?
Which plates have divergent boundaries?
Which plates have transform boundaries?
Which plate or plates have all types of boundaries?
Answer the following questions:

What phenomena would you expect to see at each of the four different plate
boundary types?

What changes do you think a visitor to the Rockies might expect to see a million
years from now?
Go to the Mountain maker, Earth Shaker simulation:
https://unctv.pbslearningmedia.org/asset/ess05_int_shake/
Try moving the divergent boundary. What happens to the ocean floor when the
divergent boundary is expanded?
Click on the convergent boundary arrow for oceanic-continental. Try moving the oceanic
plate towards the continental plate. Why does the volcano begin to erupt as you move
the convergent boundary across?
Click on the convergent boundary arrow for the continental-continental. Try moving the
continental plates together. What factors determine the height of the mountains
formed?
Click on the transform boundary arrow. Why are there no features formed on the
surface when this boundary is moved?
Questions:

How do scientists explain why, if new crust is constantly being formed from
volcanic materials, Earth's crust stays the same size?

Why are continental volcanoes associated with oceanic-continental convergent
boundaries?

Why are the Appalachian Mountains not as high as the Himalayan Mountains
even though they were formed in the same way?

Why do scientists predict that Los Angeles will be north of San Francisco in 16
million years?