2. Recall: Scientists know Earths interior is made mostly of
layers of _______________. Some layers, like the center part,
called the ______are hard and______. Other layers are not. The
layer next to the center, called the_________, is _______. Both
parts of the core are made of___________. inner core; liquid ; rock
iron and nickel; outer core; solid
3. Recall: The largest layer inside Earth is called the _____.
Its neither completely solid nor completely liquid, but_____. Its
extremely______. Earths outermost layer is the______ . This layer
is about 5 km thick under the_______ and up to 35 km thick under
the______. On top of the outer layer is the weathered rock
called______. continents ; mantle; plastic like crust; oceans;
soil; hot
4. Despite the evidences presented by Wegener, WHY was his idea
that the continents were once joined together was not accepted by
the scientific society? This made scientists conduct further
studies in search for the answer.
5. 1950s and 1960s- new techniques and modern gadgets sonars
and submersibles scientists had a clearer view of the ocean floors
discovered underwater features deep within the ocean
6. a system of ridges or mountains in the seafloor similar to
those found in the continents (mid-ocean ridges) Mid-Atlantic
Ridge: an undersea mountain chain in the Atlantic Ocean a gigantic
cleft about 32-48 km long and 1.6 km deep
7. Mid-Atlantic Ridge
8. Activity 5: Split and Separate! Simulate and describe the
seafloor spreading process. Realize the importance of the seafloor
spreading process relative to the Continental Drift Theory.
9. Paper Folder
10. Answer: Q22-27
11. Describe and explain each diagram/illustration.
12. Harry Hess
13. Magnetometer
14. Sea Floor Spreading early 1960s- Harry Hess, together with
Robert Dietz Seafloor Spreading Theory hot, less dense material
from below the earths crust rises towards the surface at the
mid-ocean ridge material flows sideways carrying the seafloor away
from the ridge, and creates a crack in the crust magma flows out of
the crack, cools down and becomes the new seafloor
15. Sea Floor Spreading allowed the creation of new bodies of
water the Red Sea -African plate and the Arabian plate diverged
pulling Australia, South America, and Antarctica away from each
other in the East Pacific Rise The East Pacific Rise -the most
active sites of seafloor spreading, more than 14 cm/yr
16. SFS rate of formation of a new seafloor is not always as
fast as the destruction of the old seafloor at the subduction zone
explains why the Pacific Ocean is getting smaller and why the
Atlantic Ocean is getting wider If subduction is faster than
seafloor spreading, the ocean shrinks When the seafloor spreading
is greater than the subduction, then the ocean gets wider
17. The SFS contradicts a part of the CDT CDT- continents moved
through unmoving oceans and that larger, sturdier continents broke
through the oceanic crust Whereas, the seafloor spreading shows
that the ocean is the actual site of tectonic activity
18. Findings that support Seafloor Spreading Theory: Rocks are
younger at the mid-ocean ridge. Rocks far from the mid-ocean ridge
are older. Sediments are thinner at the ridge. Rocks at the ocean
floor are younger than those at the continents.
19. Bring the ff: Pencil Ruler
20. Activity 6: How fast does it go! Objectives: Analyze a
magnetic polarity map. Use legends and scales of the map properly.
Calculate the rate of seafloor spreading using magnetic clues.
23. Magnetic Reversal magnetic flip of the Earth the North Pole
is transformed into a South Pole and the South Pole becomes the
North Pole due to the change in the direction of flow in the outer
core
24. Magnetic Reversal explained through the magnetic patterns
in magnetic rocks, especially those found in the ocean floor When
lava solidifies, iron bearing minerals crystallize the minerals
behave like tiny compasses and align with the Earths magnetic field
so when magnetic reversal occurs, there is also a change in the
polarity of the rocks
25. Describe and explain each diagram/illustration.
26. Age of Oceanic Crust
27. Divergent: Iceland
28. Over the last 10 million years, there has been an average
of 4 to 5 reversals per million years. New rocks are added to the
ocean floor at the ridge with approximately equal amounts on both
sides of the oceanic ridge. The stripes on both sides are of equal
size and polarity which seemed to be mirror images across the ocean
ridge.
29. What does this indicate? It indicates that indeed, the
seafloor is spreading.
30. NET RESULTS Spreading rates at transform faults Pacific
plate moves NW at 8 cm/yr N American plate moves W at 2 cm/yr
Indian plate moves NE at 12 cm/yr Pacific Ocean is shrinking and
Atlantic is growing Atlantic opened about 200 MY ago so there
should be no rocks older than this in the Atlantic
31. Most recent episode of Seafloor spreading: Pangaea first
broke into 2 pieces Sea opens between N and S continents and
Between Africa and Antarctica India moves North
32. S Atlantic opens Antarctica moving S India moving N
Australia separates and moves N
33. 50 MY in the future: 1. Africa will move N and close
Mediterranean Sea 2. E Africa will detach (Red Sea rift zone) and
move to India 3. Atlantic Ocean will grow and Pacific will shrink
as it is swallowed into Aleutian trench. 4. W California will
travel NW with the Pacific Plate (LA will be swallowed into the
Aleutian trench in 60 MY).
34. Bring the ff: (by group) dropper food color 3-5 small /
light wood blocks (or sponge cut into thin and small blocks)
