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 and water

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

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

11. Evidence:Earth’s Magnetic Field • Movement of Fe (l) in the outer core as the planet rotates. • Behaves like permanent magnet near center of Earth • Magnetic north (compass measures) differs from geographic north of planet’s axis of rotation.

12. 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. • Paleomagnetism = Study of ancient magnetism

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

14. http://nsdl.org BUT…..Magnetic North is NOT at the North Pole

15. AND…the Magnetic Field Reverses • Field reverses ~1 time every 200,000 years on average. • 400 times in last 330 million years. • Last reversal was 780,000 years ago. NORMAL REVERSE

16. Which fault is at fault?! 

17. 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 vertical or horizontal A vertical fault is comprised of a footwall and a hanging wall

18. Normal Fault Tension pulls rocks apart causing the hanging wall block to be pulled down.  Normal does not mean most common!  Why do you think it is called a normal fault? At what type of plate boundary do normal faults occur? 

19. Reverse Fault Opposite of the normal fault Compression pushes rocks together and  causes the hanging wall to be pushed up At what plate boundary do reverse faults occur?

20. Strike-Slip Fault A strike-slip fault happens  when rocks slide past  each other (shearing) Moves left or right laterally with very little horizontal movement At which plate boundary do strike slip faults occur? What is a common example of a strike slip fault?

21. The Himalaya Mountains contain many of these faults.

22. Earthquakes

23. Earthquakes • Earthquake is the vibration of Earth caused by a rapid release of energy • Often caused by slippage 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

24. Faults • Earthquakes are usually associated w/large fractures in Earth’s crust & mantle called faults • Faults are fractures in Earth where movement has occurred

25. Causes of Earthquakes • Scientists studied 1906 San Francisco 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

26. 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

28. Aftershocks & foreshocks • Aftershocks are smaller earthquakes produced after a major earthquake • Foreshocks are small earthquakes produced before a major earthquake; can be days or years before quake

29. Earthquake waves • Surface waves • Travel along Earth’s outer layer • Move up-down & side-to-side • Causes ground & anything on it to move • Most destructive • AKA L waves or Rayleigh waves

30. Earthquake waves • Body waves • P waves • Push-pull waves • Compression waves • Change volume of material they pass through

31. Earthquake waves • S waves • Most particles @ right angles to their travel • Transverse waves • Change shape of material they pass through, SOLIDs only

32. Earthquake waves • Seismogram shows all 3 types of waves • P waves arrive first – fastest traveling • S waves arrive second • Surface waves (L waves) arrive last – slowest traveling

33. Locating an Earthquake • Compare arrival times of P & S waves • Greater the difference = greater distance to focus • Earthquake distance • Developed using seismograms from earthquakes w/identifiable epicenters • 2 steps • 1. Find time interval btwn 1st P wave & 1st S wave • 2. Find on travel-time graph the equivalent time spread btwn P & S wave curves

34. Earthquake direction • Travel-time graphs from 3 or more seismographs can be used to find exact location of earthquake’s epicenter • Draw circle w/diameter in distance, where they intersect = epicenter

35. Earthquake zones • 95% of earthquakes occur in narrow zones • Most on outer edge of Pacific called circum-Pacific belt • Second belt Mediterranean-Asian belt

36. Tsunamis

37. Tsunamis • Wave caused by earthquake 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

38. 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 1-2 destructive tsunamis per year

40. Other Dangers • Landslides • Greatest damage to structures is from landslides & ground subsidence, or sinking of ground triggered by the vibrations • Fire • Start when there’s damage to gas & electric lines

41. 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.

42. 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.

43. Volcanoes Vulcan- Roman God of Fire

44. 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”

45. 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?

46. Types of Volcanoes • Shield Volcano • Built from layers of lava • Non-explosive eruptions • Not very steep, but can be big

47. Types of Volcanoes • Cinder Cone Volcano • Built from pyroclastic material • Moderately explosive, short eruptions • Small in size, steep slopes

48. Types of Volcanoes • Composite Volcanoes • Most common type • Explosive eruptions and lava flow • Built from pyroclastic material AND lava

49. Types of Volcanoes

50. Volcanic Eruptions and Hazards