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GEOLOGYI LIKE TO MOVE IT

MOVE ITPart 1 Age of Earth and scientific classificationPart 2 Plate tectonics

CONTINENTAL DRIFT

Theory

1912 Alfred Weagner proposed the theory that Earth's crust is slowly drifting on a liquid core. 

His theory was not accepted in his lifetime...but now there is a lot of evidence

National Geographic Continental Drift

http://www.youtube.com/watch?v=3uBcq1x7P34

Pangea

____________________years ago250 million

Evidence

Fit of continents

Evidence

Distribution of rocks & mountains

Evidence

-Paleoclimates- Rocks deposited at the Earth's surface (sedimentary) reflect the climate and latitude of which they form-Glacial sediments-_____________

fossils

Plate Movement

“Plates” of lithosphere are moved around by the underlying hot mantle convection cells

Unit 1-Spheres of the Earth

Questions:What evidence is there for the continents to be one land mass called Pangaea?

What causes continents to move?

Spreading ridges As plates move apart _________________is erupted to fill the gap

Effect: Underwater mountains

Divergent Boundaries

new material

Age of Oceanic Crust

Courtesy of www.ngdc.noaa.gov

Evidence: Earth’s Magnetic Field The magnetic field is caused by the

movement of liquid iron in the outer core as the planet rotates.

Behaves like a _____________________ near center of Earth

Magnetic north (compass measures) differs from geographic north of planet’s axis of rotation.

permanent magnet

How can it be monitored? Basaltic lava with iron minerals act like

compasses. When they cool, they are magnetized in

the direction of the surrounding magnetic field.

_________________ = Study of ancient magnetism

Paleomagnetism

Earth’s Magnetic Field

http://nsdl.org

Magnetic North is NOT at the North Pole

http://nsdl.org

AND…the Magnetic Field Reverses

• Field reverses ~1 time every ___________________on average.

• 400 times in last 330 million years.

• Last reversal was 780,000 years ago.

NORMAL REVERSE

200,000 years

Unit 1-Spheres of the Earth

Questions:Is a compass always going to point north?

How does the magnetic field relate to plate tectonics?

WHICH FAULT IS AT FAULT?! 

What is a fault?

A fault is a fracture in the Earth's crust that occurs when stress is applied to quickly or when stress is too great. 

It can be either _________________________

A vertical fault is comprised of a footwall and a hanging wall

vertical or horizontal

Normal Fault

Tension pulls rocks apart causing the hanging wall block to be pulled down. 

Normal ______________ mean most common! does not

Reverse Fault

_______________of the normal fault

Compression pushes rocks together and causes the hanging wall to be pushed up

Opposite

Strike-Slip Fault

A strike-slip fault happens when rocks ____________________  each other (shearing)

Moves left or right laterally with very little horizontal movement

slide past

Unit 1-Spheres of the Earth

Questions:What are the three types of faults?

What are the differences in how these faults move?

EARTHQUAKES

Earthquakes Earthquake is the vibration of Earth

caused by a rapid release of energy Often caused by _____________along a break

in Earth’s crust Focus & Epicenter

Focus is point w/in Earth where earthquake starts

Energy is released in waves Epicenter is location on surface directly

above the focus

slippage

Causes of Earthquakes Scientists studied 1906

______________quake along San Andreas fault Some areas moved 4.7 m on one side of

fault compared to the other Hypothesis was developed – force causes

rocks to bend & store elastic energy, eventually friction which holds rocks together is overcome, rocks slip at the weakest point (focus) releasing energy allowing rocks to return to original shape

San Francisco

Causes of Earthquakes _______________rebound hypothesis

Explains that when rocks are deformed, they bend then break, releasing stored energy

Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces

When strength of rock is exceeded, it suddenly breaks, causing vibrations of an earthquake

Elastic

Aftershocks & foreshocks Aftershocks are ______________earthquakes

produced after a major earthquake Foreshocks are small earthquakes produced

before a major earthquake; can be days or years before quake

smaller

A longitudinal wave and is created by ____________.Demo: push slinky, compressing the coils…

Any individual particle simply ____________________!

Longitudinal Waves

The following animation and many other wave animations in this unit courtesy of Dan Russell from Kettering University: http://www.kettering.edu/~drussell/demos.html

compression

moves back & forth

When the disturbance and resulting motion of the medium is _______________to the motion of the wave, it is called a transverse wave and is created by __________.

• Demo: stretch slinky by shaking back and forth

Transverse Waves

•Animation:

•Animation: Transverse Stadium Wave

perpendicular

tension

Seismic or Earthquake waves

Earthquakes produce both transverse and longitudinal waves• Longitudinal waves in the ground are compression waves. They travel the fastest, and thus, reach the surface first. So, they are called _________ waves (or __-waves). They do the least amount of damage.

Expansions

Compressions Undisturbed Medium

primaryp

Since we know that __________ waves cannot travel through _________, this provides evidence that the earth has a __________ core.

• Transverse waves in the ground are “shear” waves. They travel slower, and are thus, called __________ waves (or __-waves). They do more damage than the p-waves.

It is known that p-waves travel farther than s-waves. Why might that be?

secondary s

transverseliquids

liquid

Using a seismograph, the _________________ from when the p-wave arrives to when the s-wave arrives can be measured. Knowing the ________ of the two waves through the earth, the ________ to the epicenter (starting point) of the earthquake can be determined.

Seismograph

time difference

speeddistance

Locating the Epicenter of an Earthquake

__ different seismographs at __ different locations are required to find the location of the epicenter.

If each seismograph station calculates the distance from itself to the epicenter, then the location of the epicenter is the ___________ of the _________ created.

= seismograph station

epicenter

3 3

intersectionsphere

s

Ring of Fire Earthquake zones

_______of earthquakes occur in narrow zones

Most on outer edge of Pacific called circum-Pacific belt

Second belt Mediterranean-Asian belt

95%

Emergency Situations What should you do in an Earthquake? If Indoors DROP to the ground; take COVER by getting under a sturdy

table or other piece of furniture; and HOLD ON until the shaking stops. If there isn’t a table or desk near you, cover your face and head with your arms and crouch in an inside corner of the building.

Stay away from glass, windows, outside doors and walls, and anything that could fall, such as lighting fixtures or furniture.

If Outdoors Stay there. Move away from buildings, streetlights, and utility wires. Once in the open, stay there until the shaking stops. The

greatest danger exists directly outside buildings, at exits and alongside exterior walls.

Unit 1-Spheres of the Earth

Questions:What causes Earthquakes?

Where are most Earthquakes located? Why?

TSUNAMIS

Tsunamis Wave caused by ____________ on ocean

floor Causes of tsunamis

Slab of ocean floor is displaced vertically along a fault

Vibration can also set an underwater landslide into motion

Waves travel 500-950 km/hr Height in ocean is less than 1m but can

reach 30m when it hits land

earthquake

Tsunamis Tsunami warning system

Tsunami warning center in Honolulu HI Receives info about large earthquakes in Pacific Use water level in tide gauges Warnings are issued w/in 1 hr of report Only ___________________tsunamis per year1-2

destructive

Emergency Situations What should you do in a Tsunami? Follow the evacuation order issued by authorities and

evacuate immediately. Take your animals with you. Move inland to higher ground immediately. Pick areas 100

feet (30 meters) above sea level or go as far as 2 miles (3 kilometers) inland, away from the coastline. If you cannot get this high or far, go as high or far as you can. Every foot inland or upward may make a difference.

Stay away from the beach. Never go down to the beach to watch a tsunami come in. If you can see the wave you are too close to escape it. CAUTION - If there is noticeable recession in water away from the shoreline this is nature's tsunami warning and it should be heeded. You should move away immediately.

Save yourself - not your possessions. Remember to help your neighbors who may require special

assistance - infants, elderly people, and individuals with access or functional needs.

VOLCANOES

Vulcan- Roman God of Fire

What is a volcano? Volcano- Areas of earth’s surface

through which magma and volcanic gases pass

Volcano comes from the Roman word Vulcan, which means “_______”

fire

What’s inside a volcano? Magma

Chamber- molten rock that feeds a volcano

Vents- cracks in the crust

What is the difference between magma and lava?

How and why do volcanoes erupt?

Hot, molten rock (magma) is ______________(has a lower density than the surrounding rocks) and will rise up through the crust to erupt on the surface.

When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of gas (H2O, CO2, S) it has in it as to how it erupts.

__________ amounts of gas and a high viscosity (sticky) magma will form an explosive eruption!

__________ amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption

buoyant

Large Small

Explosive Eruptions

Mt. Redoubt

Explosive volcanic eruptions can be catastrophic

Erupt 10’s-1000’s km3 of magma

Send ash clouds >25 km into the stratosphere

Have severe environmental and climatic effects

Hazardous!!!

Above: Large eruption column and ash cloud from an explosive eruption at Mt Redoubt, Alaska

Pyroclastic flow Lahars/Mud flows Pyroclastic fall Lava flow Noxious Gas Earthquakes

Volcanic Hazards

Courtesy of www.swisseduc.ch

Effusive Eruptions

Effusive eruptions are characterised by outpourings of lava on to the ground.

Hawaii

Courtesy of www.swisseduc.ch

http://i.imgur.com/kLfA5ol.gif

Direct measurements of pyroclastic flows are extremely dangerous!!!

Pyroclastic Flow

Hot, fast moving, high particles concentration flows of ___________________

For example, eruption of Vesuvius, Italy in 79 AD destroyed the city of Pompeii

gas, rock, and ash

Pompeii (79AD)

On August 24, 79AD Mount Vesuvius literally blew its top, erupting tonnes of molten ash, pumice and sulfuric gas miles into the atmosphere. Pyroclastic flows flowed over the city of Pompeii and surrounding areas.

Pompeii (79AD)Pyroclastic flows of poisonous gas and hot volcanic debris engulfed the cities of Pompeii, Herculaneum and Stabiae suffocating the inhabitants and burying the buildings.

Pompeii (79AD)The cities remained buried and undiscovered for almost 1700 years until excavation began in 1748. These excavations continue today and provide insight into life during the Roman Empire.

Vesuvius today

Vesuvius remains a hazardous volcano with heavily populated flanks: around 1.5 million

people live in the city of Naples alone

Naples is situated approx. 30 km from Vesuvius

Pyroclastic flows can flow up to 100 km from source!

Bay of Naples

Vesuvius

Naples

Courtesy of www.swisseduc.ch

An eruption of Mt Peleé in 1902 produced a pyroclastic flow that destroyed the city of St. Pierre.

before after

Mt Peleé, Martinique (1902)

29,000 people died…. Only 2 survived! Why?

Pyroclastic Flow - direct impact

Courtesy of www.swisseduc.ch

Pyroclastic Fall

• Ash load– Collapses roofs– Brings down power

lines– Kills plants– Contaminates water

supplies– Respiratory hazard

for humans and animals

Lava Flow

It is not just explosive volcanic activity that can be hazardous. Effusive (lava) activity is also dangerous.

So….How do we minimize the risk of

active volcanoes?

*Volcano Monitoring

Volcano Observatories are set up on all active volcanoes that threaten the human population. These are designed to monitor and potentially to predict the eruptive behaviour of the volcano in question.

Unit 1-Spheres of the Earth

Questions:What causes volcanoes?

Is lava the only thing to worry about with volcanoes?