Chapter 1: Plate Tectonics

Earth’s Layers

Continents Changing Position

Over Time

Plates Moving Apart

Plates Coming Together

100 100 100 100

200 200 200 200

300 300 300 300

400 400 400 400

500 500 500 500

This is a solid sphere of metal found in the

center of the Earth. It is mainly made up of nickel and iron.

The Inner Core

The layer of the Earth made up of the crust and rigid rock of

the upper mantle

Lithosphere

Although the word “asthenosphere”

comes from the Greek word asthenes, meaning weak, it is

not actually weak. How can it be characterized?

layer of hotter, softer rock in the upper mantle.

Solid lithosphere rests on it. Hot tar.

Most large tectonic plates include two types of crust.

What are these types of crust?

Continental&

Oceanic

To explore the interior of the Earth, what must scientists study?

They must study the energy from earthquakes or underground explosions.

Alfred Wegener proposed this hypothesis to help

explain Earth’s continents moving over time.

Continental Drift

Theory

This supercontinent began splitting 200 million

years ago.

Pangaea

What three pieces of evidence did Alfred Wegener use to

support his hypothesis on the continents moving? And provide

detail to at least one. Fossils- ancient reptile Mesosaurus had been discovered in South America and

western Africa. Not found anywhere else.

Climate- Greenland had once been near the equator and slowly moved to the Arctic

circle.

Geology- best evidence came from finding a type of rock that was in Brazil matched

rock found in western Africa.

Huge underwater mountain ranges that circle the

Earth like the seams of a baseball. They are also formed from divergent

boundaries. Mid-Ocean Ridges

How does the age of the sea floor show that plates are

moving?

Rock is youngest near the ridge, and older farther away. Showing that older rock was carried away from the ridge some time ago.

This is a boundary where plates are moving apart. What is the name of this boundary and where are most of them found?

Divergent Boundary—in the ocean

True or False. Mid-ocean ridges are the longest chain of mountains on

Earth.

True—Mid-Atlantic Ridge

is the longest.

What is a hot spot?

an area where a column of hot material rises from deep within a planet’s mantle and heats up the lithosphere above it, often causing volcanic

activity at the surface.

Suppose a magnetic reversal occurred today. How would new rocks at mid-ocean ridges differ from the rocks that

formed last year?

The magnetic minerals in the new rocks would be aligned in the

opposite direction.

Name and describe the three types of plate movement.

1.Divergent—moving apart2.Convergent—pushing together/colliding

3.Transform—scraping past each other

This is the process in which one plate

sinks beneath another.

Subduction

True or False. Major geologic events occur at

all three types of boundaries.

True.

These are like deep canyons that form as the

ocean floor sinks.

Deep Ocean Trenches

There are 3 types of convergent boundaries. Please list all

three and describe them briefly.

Continental-continental collision: two plates carrying continental crust push

together

Oceanic-Oceanic subduction: one plate w/oceanic crust sinks

Oceanic-Continental Subduction: occurs where crust sinks under continental crust.

San Adreas Fault—the Pacific plate and the North American plate are scraping past each other along the San Andreas

Fault. Crust is not being formed or destroyed.

Please give an example of a transform boundary.