Forces of

Change

Spheres of Earth

A.Lithosphere: includes all landmasses on Earth - about 30% of the Earth’s surface

B. Hydrosphere: includes all water bodies on Earth - about 70% of the Earth’s surface

C. Atmosphere: the layer of gasses extending 1,000 miles above the Earth’s surface - 78% Nitrogen, 21% Oxygen

D. Biosphere: supports all life on Earth - animals, humans, and plants

Internal Forces

of the Earth

Structure of the Earth

A Layered Planet:

-Inner Core

- Outer Core

- Mantle

-Crust

Structure of the Earth

Structure of the Earth

Inner Core— super hot, dense and solid iron and nickel

Outer Core -Molten or liquid iron and nickel

Structure of the Earth

Mantle— Thick layer of rock (1800 miles thick); mostly solid, but has pockets of magma (melted rock)

Structure of the Earth

Crust— very thin layer; rocky surface

• Below the oceans, the crust is about 5 miles thick. Below the continents it averages 22 miles in thickness.

The Plate Tectonic Theory

1. The lithosphere— the earth’s crust and upper layer of the mantle —are broken into a number of large, moving plates.

2. The plates slide very slowly over a hot, pliable layer of mantle.

Mantle

3. The earth’s oceans and continents ride atop of the plates and constantly pull apart, collide, and grind against one another at plate boundaries

4. This constantly changes the Earth’s surface

- pushes up mountains

- creates new land

5. Most earthquakes & volcanoes occur along the plate boundaries.

The Ring of Fire is a circle of volcanic mountains surrounding the Pacific Ocean

                                           

      

Ring of Fire

What Happens When Plates Meet?

Nice to meet you!

Tectonic Plates Move in 3 Ways

1

Convergent = Collide

• If 2 oceanic plates collide, one slides under the other.

• Islands often form

this way.

Two of a Kind - Oceanic

Convergent

• If 2 continental plates collide, the land folds or cracks into huge blocks.

• Example: Mountains

Two of a Kind - Continental

Continental Convergent

Two Different A.When a continental and sea plate meet,

the heavier oceanic plate slides under the lighter continental plate.

• The sea plate becomes magma and burst to through the crust to form volcanic mountains.

Convergent

This is called Subduction

Two DifferentB. Or when sea platesslide under

continentalplates, they leavebehind debris. This

cancause continents togrow outward. It iscalled accretion.

Convergent

2

Plates pull apart from each other and the deep rift, or crack, allows magma to well up between plates.

These areas are likely to have earthquakes, volcanoes, and rift valleys.

Divergent = Pull Away

Spreading ZoneTwo sea plates moving away

3

Transform =Move Horizontally

•When they meet, friction can lock them into place for a long periods, allowing pressure to build below the crust.

•When the pressure gets too great the plates come unstuck and move. This is an earthquake.

At a FAULT, the plates will grind or slide past each other rather than colliding. Example: San Andres Fault.

Fault

Other Information

Hot SpotsHot regions deep within the mantle thatproduce magma, which rises to the

surface.

Volcanic island chains form as oceanic plates

drift over the hot spot.

Example: Hawaiian Islands.