Forces of Change

Spheres of Earth 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

Structure of the Earth A Layered Planet: Inner Core Outer Core Mantle Crust

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.

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 Two of a Kind - Oceanic If 2 oceanic plates collide, one slides under the other. Islands often form this way.

Two of a Kind - Continental Convergent Two of a Kind - Continental If 2 continental plates collide, the land folds or cracks into huge blocks. Example: Mountains

Continental Convergent

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.

This is called Subduction

Convergent Two Different B. Or when sea plates slide under continental plates, they leave behind debris. This can cause continents to grow outward. It is called accretion.

2

Divergent = Pull Away 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.

Spreading Zone Two 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.

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

Other Information

Hot Spots Hot regions deep within the mantle that produce magma, which rises to the surface. Volcanic island chains form as oceanic plates drift over the hot spot. Example: Hawaiian Islands.