The Dynamic Earth

Environmental ScienceMs. Moore

1/28/13

The Earth as a System

• The Earth consists of rock, air, water, and living things that all interact with each other– Geosphere: rock– Atmosphere: air– Hydrosphere: water– Biosphere: living things

The Geosphere

• The solid part of the Earth that consists of all rock, as well as soils and loose rocks on the Earth’s surface, makes up the geosphere.

• Most of the geosphere is located in Earth’s interior.

Discovering Earth’s Interior

• How do we study the interior Earth?– Seismic waves: travel through the Earth’s interior

during an earthquake– We use the same thinking when figuring out if a

melon is ripe.

The Earth’s Composition

• Using chemical properties, scientists divide Earth into 3 layers:– Crust: composed of light elements; makes up less

than 1% of the Earth’s mass; thinnest layer, 5-8km thick beneath oceans and 20-70km thick beneath continents

– Mantle: beneath crust; makes up 64% of Earth’s mass; 2,900km thick; made up of rocks

– Core: Earth’s innermost layer; densest elements; radius of 3,400km

Structure of the Earth• Using physical properties, scientist divide the

Earth into 5 layers:– Lithosphere: outer layer; 15-300km thick; includes

the crust and uppermost mantle; divided into tectonic plates

– Asthenosphere: layer beneath lithosphere; plastic, solid layer of the mantle made of rock

– Mesosphere: lower part of the mantle; 2,550km thick– Outer Core: 2,200km thick; outer shell of core; made

of liquid nickel and iron– Inner Core: 1,228km radius; sphere of solid nickel

and iron at the center of the Earth

Activity

• Ms. Moore will divide you into 5 groups

• Create a presentation about the layers of the Earth– Include compositional and physical layers– Include facts about each layer

• Be prepared to present your project to the class

Plate Tectonics

• Lithosphere is divided into pieces called tectonic plates. They glide across the asthenosphere like a chunk of ice drifts across a pond.

• Major tectonic plates:– Pacific– North American– South American– African– Eurasian– Antarctic

Plate Boundaries

• Plates may move away from one another, collide, or slip past one another. The forces produced can cause mountains to form, earthquakes to shake the crust, and volcanoes to erupt.

Convergent Boundary

• A convergent boundary occurs where two plates are pushing toward each other.– The boundary between the Eurasian Plate and the

Indain Plate at the Himalayas– The boundary between the Nazca Plate and the

South American Plate along the west coast of South America

Divergent Boundary

• A divergent boundary marks two plates that are moving apart from each other.– The boundary between the African Plate and the

Arabian Plate in the Red Sea– The boundary between the Pacific and Antarctic

Plates– The mid-Atlantic Ridge, made up of the boundary

between the North American and Eurasian Plates in the North Atlantic, crossing Iceland, and the South American and the African Plates in the South Atlantic

Transform Boundary

• A transform boundary occurs where two plates slide past each other.– The boundary between the Pacific Plate, crossing

New Zealand– The boundary between the Pacific Plate and the

North American Plate in California

Earthquakes

• A fault is a break in the Earth’s crust