1. German meteorologist
Alfred Wegener proposed the hypothesis of continental drift
2. According to the
hypothesis of continental drift, continents have moved slowly to their current
locations
3. Wegener suggested that
about 200 million years ago, all continents once were connected as one landmass
called Pangaea
4. Pangaea means “all land”
5. Wegener’s ideas about
continental drift were controversial and not believed until after 1930.
6. Fossil clues, climate
clues, and rock clues provided evidence that continental drift occurred.
7. Fossils of Mesosaurus, a freshwater dinosaur provided evidence that
continental drift occurred.
8. Tropical plant fossils,
Glossopteris, have been found in Antarctica, Africa, Australia, South America,
and India.
9. Glacial deposits, rock
surfaces scoured and polished by glaciers have been found in South America,
Africa, India, and Australia.
10. Rock clues-similar rock
structures are found on different continents.
Mountains identical to parts of the Appalachian Mountains have been
found in Greenland and Western Europe.
11. Wegener’s idea of
Continental Drift were rejected because scientists could not give any
explanations how the continents could move.
Seafloor Spreading
12. In the 1940’s and 1950’s, scientists began
using sound waves to map the ocean floor.
13. Sound waves echo off the ocean floor &
the longer they take to return to the ship, the deeper the ocean.
14. using sound waves,
scientists discovered an underwater mountain chain called the mid-ocean ridge.
15. mid-ocean ridge is the
world’s longest chain of mountains. Is
where the sea-floor is spreading apart.
16. Harry Hess, a scientist,
presented his theory of seafloor spreading to explain continental drift in the
1960,s
17. seafloor spreading
is caused by magma rising up towards the
bottom of the ocean crust. Convection
currents in the magma split the crust apart along the mid-ocean ridge letting
lava flow through the crack causing
new seafloor.
18. Glomar Challenger-1968,
research ship that discovered that rocks closest to mid-ocean ridge were the
youngest and that the farther away, the older the rocks.
19. youngest rocks are found
near the mid-ocean ridge and rock gets older the farther away you get.
20. seafloor spreading causes the ocean to get
wider! It pushes the continents away from each other.
21. magnetic alignment in rocks on the seafloor, on
both sides of the mid-ocean ridge, has recorded the periodic reversals of the
Earth’s magnetic field.
http://education.sdsc.edu/optiputer/flash/seafloorspread.htm
http://www.uwsp.edu/geo/faculty/ritter/glossary/S_U/sea_flr_spread.html
Directions: Study the following
diagram of the seafloor. Then match the letters to the statements below.
Directed
Reading for Mastery
______A. Molten rock flows onto the seafloor and hardens as
it cools.
_______B. Hot, molten rock is forced upward toward the
seafloor at a mid-ocean ridge.
_______C. New seafloor moves away from the ridge, cools,
becomes denser, and sinks.
_______D. Molten rock pushes sideways in both directions as
it rises, moving the
mantle with it.
Plate Tectonics
22. theory of plate
tectonics-Earth’s crust and part of the upper mantle are broken into sections.
23. plates-the
sections of the lithosphere
24. lithosphere-the
crunchy part of the Earth, is the crust and the very top of the mantle
25. asthenosphere-the gooey, plasticlike,
top part of the mantle that the lithosphere slides upon
26. plate
boundaries-the edges of plates, where they meet.
27. convection
currents inside the Earth are believed to cause the movement of the plates.
28. convection current
is the heating, rising, cooling, and sinking of magma. As magma gets heated it becomes less dense
which causes it to rise upward through the mantle. As it cools, it sinks back
downward. The rising and falling creates
a current in the magma.
29. three movements of
plates-towards each other, away from each other, and past each other like cars
on a highway
30. If one boundary changes, it will cause changes at other
boundaries.
31. divergent
boundary-when two plates move AWAY from each other, ß à.
32. divergent boundaries cause mid-ocean ridges!!
33. new crust is created by divergent boundaries, mid-ocean
ridges
34. If new crust is created, old crust must be recycled by
the Earth.
35. convergent boundary-when two plates come together, àß.
36. convergent
boundaries come together, denser oceanic plates/crust will sink beneath
continental crust
37. subduction zone-where oceanic plates goes down into the
mantle.
38. volcanoes can form
above subduction zones
39. deep-sea trenches
are formed at convergent boundaries of two ocean plates.
40. subducted plates melt creating new magma. New magma can cause volcanoes or be used to
form new mid-ocean ridges.
41. mountain ranges-when continental plates converge, they
will crumple up.
42. transform
boundaries-where two plates slide past each other.
43. Earthquakes occur
at convergent boundaries and transform boundaries.
44. San Andreas
Fault-a transform boundary in California that causes lots of earthquakes.
45. seismic waves-
energy release as rocks move and break in the crust during an earthquake
46. fault-area where
rocks break and move because of plate movement
47. faults can cause
breaks and shifts in rock layers.
Earthquakes and
Volcanoes!
48. focus-the exact point where the energy is released during
an earthquake, seismic waves travel outward from the focus.
49. earthquakes
produce three types of seismic waves, Primary, Secondary, and Surface waves
50. Primary waves move
the fastest
51. Surface waves
cause the most damage!!!
52. epicenter-surface location above the focus, where the
earthquakes energy reaches the surface and spreads outward like a ripple of
surface waves.
53. seismograph –instrument used to measure Seismic waves from earthquakes
54. seismologists -Scientists who study earthquakes and
seismic waves
55. magnitude is a measure of the energy released by an
earthquake.
56. Richter magnitude scale is used to describe the strength
of an earthquake Each magnitude is 10 times stronger than the last. Magnitude 2 is 10 times stronger than a
magnitude 1 and a magnitude 3 is 100 times stronger than a 1.
57. tsunami-ocean waves caused by earthquakes, can be as
large as 30 meters tall.
58. volcano is
an opening in Earth that erupts gases, ash, and lava
59. Volcanic mountains form when layers of lava, ash, and
other material build up around these openings
60. Earth has more than 600 active volcanoes
61..volcanoes can be active, dormant (sleeping) or extinct
(dead)
62. magma reaches Earth’s surface and flows out through an
opening called a vent
63. crater the steep walled depression around a vent.
64. Ring of Fire is an area of frequent earthquakes
and volcanic eruptions encircling the basin of the Pacific Ocean. It follows the plate boundaries.
65. fault-block
mountains are formed by huge faults
66. Rift valleys and
mid-ocean ridges are cause by divergent plates.
67. The Indian plate and Asian plate boundary is a convergent
boundary. It is moving at 5 cm per year
causing the Himalayan Mountains to keep growing.
68. strike-slip faults are found along divergent boundaries
moving in opposite directions.
69. scientists can measure the movement of plates using
satellites and lasers.
70. Hawaii is moving
towards Japan at 8.3 cm per year.
71. three types of
plate boundaries are convergent, divergent, and transform.