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, when these areas are under great stress, we experience an earthquake.

• The Richter scale is used by scientists to quantify the magnitude of an earthquake.– 2.0 to 9.5

• The majority of earthquakes take place at or near tectonic plate boundaries.

Volcanoes• A volcano is a mountain built from magma (melted rock);

they are often found near tectonic plate boundaries.

• A volcano erupts when the pressure of the magma inside becomes so great that is blows open the solid surface of the volcano.– If a volcano has magma running out of it all the time, then

pressure never builds up.

• Major volcanic eruptions can change Earth’s climate for several years.– Ash and gases reduce the amount of sunlight that reaches the

Earth’s surface drop in average global surface temperature.

Erosion

• The removal and transport of surface material is called erosion.-this is how geologists know that the round topped

Appalachian mountains are older than the jagged Rocky mountains in the west.

• 2 types:– Wind– Water

The Atmosphere• Earth is surrounded by a mixture of gases known as the

atmosphere.– Nitrogen = 78% (volcanic eruptions, dead organisms decay)– Oxygen = 21% (plant production– Others = 1% (Ar, CO2, CH4, and water vapor)

• The atmosphere is pulled toward Earth by gravity.– The atmosphere is denser near the Earth’s surface

Atmosphere Composition

NitrogenOxygenOther

Layers of the Atmosphere• Nearest to Earth’s surface = troposphere– Weather occurs here; Densest layer; Temp drops as

• Above troposphere = stratosphere– Temp increases as ; ozone (O3) reduces UV to Earth

• Above stratosphere = mesosphere– Coldest layer of atmosphere (-93°C)

• Farthest from Earth’s surface = thermosphere– Absorbs radiation; hottest layer (2,000°C); lower thermosphere =

ionosphere = aurora borealis

Energy in Atmosphere

• Energy from sun is transferred in the Earth’s atmosphere by 3 mechanisms:– Radiation: transfer of energy across space (fire

heat)– Conduction: flow of heat from warmer object to

colder object in direct contact (stove)– Convection: transfer of heat by air currents (hot air

rises and cold air sinks)

Greenhouse Effect • Why does your car

get hot on a sunny day?

• The greenhouse effect is the process in which gases trap heat near the Earth.– Without this effect,

it would be too cold for life to exist.

The Hydrosphere

• Hydrosphere– Includes all of the water

on or near the Earth’s surface.

• The Water Cycle– Continuous movement of

water into the air, onto land, and back to water.

Water Cycle

• Evaporation: liquid water is heated by the sun and rises into the atmosphere as water vapor

• Condensation: water vapor forms water droplets on dust particles = cloud formation

• Precipitation: large water droplets fall from clouds as rain, snow, sleet, or hail

Earth’s Oceans

• What are the Earth’s oceans? Put them in order from largest to smallest.– Pacific, Atlantic, Indian, and Arctic.

• What makes up the ocean?

ChlorineSodiumMagnesiumSulfurCalciumPotassiumOther

Ocean Temperature Zones

Biosphere

• Biosphere: where life exists– Uppermost part of the geosphere, most of the

hydrosphere, and the lower part of the atmosphere

Lab

• Earthquake Exercise

• Volcano Exercise

• The Water Cycle

• Biosphere Model