EARTH SCIENCE

A Quick Review

Where are we?

• 3rd planet from the sun• About 92 million miles

– Perfect distance to balance warmth– “The Water Planet”

Who are we?• Geosphere• Hydrosphere• Atmosphere• Biosphere

Earth’s History• About 4.6 billion years old (according to rock

record)• Geologic Time scale - broken down into eons,

eras, periods and epochs. (Precambrian epoch = 87% of time scale)

• Divisions mainly dependent on rise of certain types of organisms or major events.

Earth’s History

• 3 major concentric zones

• Core:– Solid inner – due to

pressure (Ni & Fe)– Molten outer - creates

magnetic field (Fe & S)

• Mantle:– Mostly solid– Asthenosphere =

slowly flowing

• Lithosphere:– Thin rigid– Contains the crust

Earth’s Composition

Earth’s Magnetic Field

Earth’s Crust• Oceanic crust – mostly basalt (more dense,

~3.0g/cm3)• Continental crust – mostly granite (less dense,

~2.7g/cm3)

Plate Tectonics

• Nuclear decay in the core releases heat into the mantle and asthenosphere causing convection currents that create plate movement

Plate Tectonics

• Convection currents have caused the mass movement of plates over millions of years.

• The movement of these plates is called “Continental Drift”.

Plate Tectonics

• Each individual plate (about 12) is made of lithosphere and mantle.

Plate Tectonics

• Today, the plates are still in motion – – PLATE TECTONICS

– http://sos.noaa.gov/videos/Paleo3.mov

Plate Tectonics

Plate Tectonics• The plates today:

Plate tectonics• Plate boundaries – edges of the plates

– Three types: convergent, divergent and transform

Earth’s Crust• Convergence (subduction)

• Creates mountains and volcanoes

Earth’s Crust

• Divergence (ridge formation)– Creates volcanoes and new crust

Earth’s Crust

• Transform – plates sliding past one another.– Creates

earthquakes

Volcanoes• Active• Dormant• Extinct

• Subduction volcanoes– At plate boundaries

• Hot spot volcanoes– In the middle of

plates

Volcanoes

• Rift Volcanoes– Form new oceanic crust

Earthquakes• Each

black dot is the

location of an

earthquake

Earthquakes

• Anatomy:– Fault– Focus– Epicenter– Waves

Rock Cycle• Rocks come from rocks

• Time, erosion, pressure and heat create 3 basic types– Igneous– Sedimentary– Metamorphic

Rock Cycle•Erosion

Soil• A crucial link between

biotic (living) and abiotic (nonliving)

Earth’s orbit and rotation

• Revolution, rotation and tilt determine our days and seasons.

Seasons

• Spring in the Northern, Autumn in the Southern

Seasons

• Summer in the Northern, Winter in the Southern

Seasons

• Autumn in the Northern, Spring in the Southern

Seasons

• Winter in the Northern, Summer in the Southern

The Atmosphere• A layer of gases

held close to the Earth by gravity

• With the help of the sun, it’s where our weather and climates occur

Atmosphere

• Troposphere – all of the weather, most of the water vapor and clouds.

• Well mixed layer.• Area of the

atmosphere that holds the greenhouse gases

The Greenhouse Effect• Without the

greenhouse gases (CO2, H2O, and CH4) in the atmosphere, we wouldn’t survive.

Atmosphere

• Stratosphere – not well mixed.

• Contains the ozone layer (O3)

Atmosphere

• Mesosphere – where meteors usually burn up.

Atmosphere• Thermosphere

(or Ionosphere)

• Thinnest gas layer– Aurora’s– Space shuttles– Ionization

(absorption of solar wind)

– Reflects radio waves

Atmosphere

• Exosphere – Satellites – Lightest gases –

H2 and He

Atmosphere• Magnetosphere – area where the magnetic

field of the earth dominantly controls the movements of gas and charged particles.

Hydrosphere & Biosphere

• We’ll cover these later…..