tour of plate boundaries 2010

8/2/2019 Tour of Plate Boundaries 2010

http://slidepdf.com/reader/full/tour-of-plate-boundaries-2010 1/63

The Relationships

Between Plate Boundaries

and Tectonic Landforms



The earth’s surface is covered with a variety of wonderful

and interesting landforms…

Island arcs

Volcanoes

Mountains



And valleys bordered

by steep cliffs,

Just to name a few!



How did these landforms originate?

How does it relate to our dynamic,

changing earth?

…These are questions that curious and analytical

scientific minds have only really been able to

answer in the last 40-50 years!



Courtesy of pictures from NASA’s website:

“Earth from Space”

http://earth.jsc.nasa.gov/land.html

We are going to take a “Virtual Tour” of the Earth to

explore these Tectonic Landscapes and put into “real-

world” context what we have learned in class.



But first a review…

An important modern theory about the forces

that drive plate tectonics is that the plastic,

partially melted asthenosphere is undergoing

convection.

This movement of materials below the earth’s

lithosphere is thought to be causing the plates

of the earth’s lithosphere to move too!



As you have learned, where there is upwelling of the

asthenosphere, the crust above spreads apart, and new

material from below bulges up into ridges. Where there issubsidence of the asthenosphere, the crust is being pulled

down along with it to form depressions, or trenches. This

can be visualized superbly in this diagram.



This

movement

of theastheno-

sphere

causes the

lithosphere

plates to be

pulled apart

or pushed

together!This creates

the different

plate

boundaries,

which inturn createsthe

landscapes

we see on

earth today!



Let’s review the 3 types of plate

boundaries we have discussed so

we can better understand the

pictures we are about to see.



Plate Boundaries

1. Divergent: Where tension forces are pulling the

earth’s plates apart.

(where plates move away from each other)

2. Convergent: Where compression forces pushthe earth’s plates together

(where plates crash into each other)

3. Transform: Where shearing forces cause the

earth’s plates to slide past each other.

(where plates rub against each other in opposite directions)



How do scientists know where

plate boundaries are, and of what

type?

By studying where the earth is

under stress.

How do scientists know where

the earth is under stress?By identifying where earthquakes

are and how deep they are!



Shallow earthquakes are found along divergent, transform, and rift

boundaries, and where continental crust is colliding.

Deep earthquakes are found along what kind of zones?!

* * *



O.K.! Enough Review! Let’s take off and look at

some real-life landforms!

Our first stops will take us to CONVERGENT boundaries.

Stop 1: Oceanic crust colliding into oceanic crust



54

3

21

COUNTDOWN….



LIFTOFF!!!!



We are going to fly over Alaska and

the Aleutian Islands

Aleutian

Islands

What features should we be looking for?



Unimak Island



Turn to page 5 in your Earth

Science Reference Tables…

What tectonic feature do yousee associated with the

Aleutian Islands?



Volcanic Island Arcs are associated with trenches!

Why is this so?!

Wh t t f l ld b t di



What type of lava would be extruding

from these volcanoes? (See page 6 of your

reference tables.)



Stops 2&3: Oceanic crust colliding with continental crust



We will be visiting the

state of Washington

in order to view plate

tectonic features thatresulted when the

Juan de Fuca Plate

(oceanic crust)

collided with theNorth American Plate

(continental crust.)

Based on the map tothe right, and in the

next slide, what

features should we be

looking for?



Cascade Range, Washington



Mount Rainier



Mount Saint Helens



A similar situation

exists in western

South America, but

the plates involvedare different.

What plates areinvolved in this

collision between

oceanic and

continental

crust?



Now we’re off to Chile and Peru to

check out the landforms there!

Stop 3: South America



Chile



Look at your reference table again. What feature do you see on

the west side of South America that is associated with

convergent boundaries and the subduction that results?

What is probably happening to the asthenosphere here?

Again, what type of lava would be extruding



Again, what type of lava would be extruding

from these volcanoes in Washington State and

western South America?



Stop 4: Continental crust colliding with

continental crust

What features do we expect to find here?



We’re off to Southeastern Asia, one of the best

places to observe this type of plate boundary!

India

China

Nepal



Himalayas

India

China



Mount Everest



Mount Everest

29,035 feet tall! (8850 meters)



Use your reference table to

determine what plates are colliding

to form the Himalayas.



Now we have reached the

second part of our journey:

Exploring DIVERGENT boundaries…

Stops 5&6:



A flight over part of Africa’s Rift Valley

will demonstrate this.



First, find the East African

Rift on your reference table

and determine what plate the

rift is found on.

Here are some



volcanoes from

the Rift Valley.

Knowing this is

a divergentzone, what type

of lava will

extrude from

them?

Lengai VolcanoSteep cliff of

rift valley



A d h d i i f h l



And here are some dramatic pictures of the lava

from these volcanoes!



…And now to explain how

rifting can form volcanoesAND large lakes…

The uprising

th h h

..and magma coming from the spreading center can form volcanoe



asthenosphere here

has caused tensionforces which have

pulled apart the

continental crust.

The brittle crust has

fractured and a

section in the middle

has downfaulted into

the developing gap

(rift.)

Water filled into

the gap, creating a

freshwater lake.

There are two

stunning

examples of this

in Africa!



Stop 5: Malawi, Africa



Lake Malawi



And next to Tanzania…



Lake Tanganyika

A d th l t t f j



And the last part of our journey…

Stop 7: A TRANSFORM BOUNDARY

We’re still in Africa— Zimbabwe this time!

M t th t l t f b d



Transform

Movement that occurs along a transform boundary:



Where is the evidence for a

transform fault in this area

of Zimbabwe?



And our final stop…

A PASSIVE CONTINETNAL MARGIN



Greenlawn



Home Sweet Home!



In Summary…

Wait a second…I’m tired from all this runningaround and being a tour guide…you do it!!!

1. What are the three main plate boundaries?

Describe the movement at each.

2. How does each plate boundary affect what

type of landscape results? Give specific

examples for each one!

3. Explain how the asthenosphere drives plate

tectonics.

tour of plate boundaries 2010

Documents