Friday 1-25 ps

Intro to earth Science

Earth Science?

• Geology

• Meteorology

• Oceanography

• Hydrology

• Seismology

• Ecology

Definitions

• Earth Science is the study of the earth, how it functions and the connections to the life that lives or has lived on it

• Meteorology – atmosphere

• Oceanography/Hydrology- water

• Seismology- inside the earth

• Ecology- relationship between life and its environment

Our focus

• Overview of the science

• Connection to physical concepts

• History of the Earth

Statistics about the Earth

• Shape of Earth is an oblate spheroid

(only just 40 miles difference in circumferences)

Circumference is about 24,000 miles around

Radius is about 3800 miles

Diameter 7600 miles

Distance between New York and Los Angeles is 2400 miles

• Trip = 1/10 around the world

= 2/3 to the center of the earth

Earth facts

• Relatively smooth for the scale

• Highest mountains are 5.5 miles from sea level

• Deepest trenches about 7 miles below sea level

Facts of Earth

71 % of Earth is covered by water

97% of that water is salty

Air we breathe at this point in earth’s history is made up of

78% nitrogen21 % oxygen1% other gases (including CD)

The Pacific ocean

Largest ocean

at present

64 million square

Miles

It would take 244

States of Texas

To cover the same

area

Trash in the ocean

How old is the Earth?

a) About 7000 years

b) About 4.5 million years

c) About 180 million years

d) About 1.8 billion years

e) About 4.5 billion years

Explanation

A) age derived from calculations based on info from the Bible

B) Age of the first species that could be considered human

C) Last time that Africa was attached to North America

D) First time that multicellular life emerged

E) Time of the formation of Earth

How many lifetimes could a normal modern American have lived since the formation of the

Earth?

About 60 million lifetimes

Change is the only constant in the history of Earth

65 million years ago, the ancestor of the modern whale walked the Earth looking more like a dog than a whale

How hot is the Earth?

• Up to 140° F • Down to -100°F

Black Smoker Vent at the bottom of the ocean (500°F)

Inside the earth?

• Deepest that man has traveled into the earth?

A couple of miles down in the gold mines of South Africa 1 degree for every 33 m

Without air conditioning it would be around 160-170°F

With air conditioning it is 100 degrees with a 100% humidity

South African Gold Miner

Deeper into the earth

• About 20-40 km down = 350 ° F,

the temperature you bake a cake

About 1000-1200 miles down = 2300 ° F

At the center of the Earth = up to 11,000 °F

In other words, 110 times more hot than the hottest summer day you have ever experienced

Scale is different in this portion of the class than before

• Cross section of the earthInner coreOuter CoreMantle

AsthenosphereLithosphere

CrustHydrosphereAtmosphere

Magnetosphere

Inner Core

• Solid Metal, nickel and iron

• Under incredible temp and pressure

• Pressure keeps it solid

• Around 1000 mile thick in diameter

Outer core

• Same composition as the inner core• Less heat and pressure• Liquid• The movement of the Iron liquid, generates the

Earth’s magnetic field• Slightly thicker than inner core

The volume occupied by both cores is about 29.5% of the Earth’s total

Mantle

• Thickest section of the interior of the earth

• The entire mantle Comprises 80% of Earth volume

• The top of the mantle is further divided into 2 important subsections– Lithosphere– Asthenosphere

Mantle subsections

Lithosphere

topmost layer of mantle (nearest to surface of Earth)

solid, brittle

Asthenosphere

underlies the lithosphere

texture like silly-putty, bends under pressure

Crust

• The layer of the earth next to the surface• Very thin

– Oceanic 2-4 miles– Continental 40-65 miles

• The least dense of all layers– Ocean crust is denser than continental crust

• We have never drilled all the way through the crust

The Moho

• The boundary between the crust and the lithosphere

How do you think we know anything about the inside the

earth?

Different form of Echolocation

• Using seismic waves• Created by vibrations of the Earth• Using time to indicate distance and type of

material

• Causes of vibration• Natural: Earthquakes• Man-made: Gunshots

Using an air-gun to create seismic waves

A cross sectional map using info from seismic waves

Two types of Seismic waves used

• P-waves

Primary-pressure wave (longitudinal)

Fastest wave

Some of the wave goes through all

material, some reflects back

Changes direction at each boundary

S-waves

• Secondary, shear

• Slower than P-waves

• Can not go through liquid

Info from Seismic waves

• Can tell the texture of the rock through interpretation of the speed of seismic waves

• Seismic waves move faster in more dense material

• The s-waves can not travel thru any liquid

Seismic wave speed

• Faster in lithosphere than crust

• Slows down in Asthenosphere

• Increases through the rest of the mantle

• Drops off in Outer CoreNo S waves

Shadow Zone

Magnetosphere

• The range of Earth’s magnetic field

• Extends beyond the atmosphere into space

• Northern lights

• May be caused by the movement of the Earth’s liquid core

There may be another source of magnetic field

• Both Sun and Moon have magnetic fields

• Sun contains very little iron

• Moon does not have a liquid core

Northern Lights

• Aurora Borealis• Result from the interaction between the

-Solar wind (charged particles expelled from the outer edge of the sun)

-Earth’s magnetosphere

-Earth’s Atmosphere

Best seen in winter (less water vapor in air) at the poles

Fig. 12-26, pg. 356