Geology I like to move it move it

1. GeologyI like to move it move it Part 1 Age of Earth and scientific classification Part 2 Plate tectonics

2. Continental Drift

3. 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

4. Pangea 250 million ____________________years ago

5. Evidence Fit of continents

6. Evidence Distribution of rocks &  mountains

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

8. Plate Movement • “Plates” of lithosphere are moved around by the underlying hot mantle convection cells

9. Questions: What evidence is there for the continents to be one land mass called Pangaea? What causes continents to move? Unit 1-Spheres of the Earth

10. Spreading ridges As plates move apart _________________is erupted to fill the gap Effect: Underwater mountains Divergent Boundaries new material

11. Age of Oceanic Crust Courtesy of www.ngdc.noaa.gov

12. 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

13. 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

14. http://nsdl.org Earth’s Magnetic Field

15. http://nsdl.org Magnetic North is NOT at the North Pole

16. 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. 200,000 years NORMAL REVERSE

17. Questions: Is a compass always going to point north? How does the magnetic field relate to plate tectonics? Unit 1-Spheres of the Earth

18. Which fault is at fault?! 

19. 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

20. Normal Fault Tension pulls rocks apart causing the hanging wall block to be pulled down.  Normal ______________ mean most common!  does not

21. Reverse Fault _______________of the normal fault Compression pushes rocks together and causes the hanging wall to be pushed up Opposite

22. 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

23. Questions: What are the three types of faults? What are the differences in how these faults move? Unit 1-Spheres of the Earth

24. Earthquakes

25. 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

26. Causes of Earthquakes San Francisco • 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

27. Causes of Earthquakes Elastic • _______________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

29. 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

30. Longitudinal Waves A longitudinal wave and is created by ____________. Demo: push slinky, compressing the coils… Any individual particle simply ____________________! compression moves back & forth 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

31. Transverse Waves • 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 perpendicular tension • Animation: • Animation: Transverse • Stadium Wave

32. 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. primary p Compressions Undisturbed Medium Expansions

33. 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. s secondary It is known that p-waves travel farther than s-waves. Why might that be? transverse Since we know that __________ waves cannot travel through _________, this provides evidence that the earth has a __________ core. liquids liquid

34. 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. time difference speed distance Seismograph

35. 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. 3 3 epicenter = seismograph station intersection spheres

36. 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%

37. 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.

38. Questions: What causes Earthquakes? Where are most Earthquakes located? Why? Unit 1-Spheres of the Earth

39. Tsunamis

40. Tsunamis earthquake • 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

41. 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 year 1-2 destructive

43. 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.

44. Volcanoes Vulcan- Roman God of Fire

45. 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

46. 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?

48. 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

49. Explosive Eruptions • 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!!! Mt. Redoubt Above: Large eruption column and ash cloud from an explosive eruption at Mt Redoubt, Alaska

50. Volcanic Hazards • Pyroclastic flow • Lahars/Mud flows • Pyroclastic fall • Lava flow • Noxious Gas • Earthquakes Courtesy of www.swisseduc.ch