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Reading Check question 1. Section 1
Who proposed Continental drift?
The German meteorologist Alfred Wegener proposed the continental drift.
Reading Check question 2. Section 2
How do Mesosaurus fossils support the past existence of Pangaea?
Mesosaurus was found in South America and Africa, but this reptile lived in
freshwater and land. Wegener hypothesized that the two continents were joined
like a puzzle.
Section 1 Assessment
1. Why were Wegener’s ideas about continental drift initially rejected?
Wegener’s ideas about continental drift were initially rejected because the
evidence he presented wasn’t enough to convince many people.
2. How did Wegener use climate clues to support his hypothesis of continental
drift?
Wegener showed that some of the fossils from warmer climates were found
in the cold Artic Ocean and there were some glacial deposits and scoured,
polished rock surfaces in South America, Africa, India, and Australia.
3. What rock clues were used to support the hypothesis of continental drift?
The rock clues that supported Wegner’s hypothesis is that some of the same
rock structures on one continent were found on another continent like the
Appellation Mountains are found on the eastern part of the United States,
Greenland, and Western Europe.
4. In what ways do fossils help support the hypothesis of continental drift?
Fossils helped prove this hypothesis because fossils like the Mesosaurus and
Kannemeyerid are either or both land and freshwater reptiles but their
fossils are only found in two or three different places of the world and
nowhere else. This showing that the continents had to be connected in order
for the fossils to get into different places of the world.
5. Why would you expect to see similar rock structures on two landmasses
that were connected at one time?
You would see similar rock structures on two landmasses that were once
connected because the landmasses are like a jigsaw puzzle, the puzzle must
be continuous.
Reading Check question 1. Section 2
How were mid-ocean ridges discover?
Mid-ocean ridges were discovered when using the echolocation sound waves to
measure how deep the water is.
Reading Check question 2. Section 2
How does new seafloor form at mid-ocean ridges?
When the seafloor spreads, the magma flows upward and fills in the cracks. When
the magma cools and becomes solid there is a new seafloor.
Section 2 Assessment
1. What properties of iron-bearing minerals on the seafloor supporting the
theory of the seafloor spreading?
Iron-bearing minerals, such as magnate, are found on the seafloor in rocks
that can record the Earth’s magnetic field when ever the Earth changes.
When the Earth Changes the Magnetic field also changes.
2. How do the ages of the rocks on the ocean floor support the theory of
seafloor spreading?
The older rocks are being pushed outward away from the ocean ridges while
the younger rocks and cracked and filled in with magma creating new
seafloors.
3. How did Harry Hess’s hypothesis explain seafloor movement?
Harry Hess explained that hot, less dense material below the surface of the
Earth’s crust rises toward the surface at the mid-ocean ridges. Then flows
sideways pushing the ridges in both directions while magma fills in the fresh
cracks. Cools and becomes a new seafloor.
4. Why does some partly molten material rise toward Earth’s surface?
Partly molten material is forced up because its density is less than the
density of the surrounding material.
5. The ideas of Hess, Wegener, and others emphasize that Earth is a dynamic
planet. How is seafloor spreading different from continental drift?
Continental drift was thought that the continents plowed through the ocean.
Seafloor spreading was about the tectonic plates diverging, pushing the
continents away from each other.
Reading Check question 1. Section 3
What are the general ways that plates interact?
Tectonic plates can move toward each other colliding, pull apart, or slide along each
other.
Reading Check question 2. Section 3
What happens when seismic energy is released as rocks in Earth’s crust break and
move?
When seismic energy is released this creates earthquakes.
Reading Check question 3.Section 3
What features occur where plates converge?
The features that are caused from plates colliding are massive folds in the Earth or
mountain ranges.
Section 3 Assessment
1. What happens to plates at a transform plate boundary?
A transform plate boundary is when two plates slide past each other, moving
in opposite directions or same direction at different speeds. If one slips past
another suddenly this will create an earthquake.
2. What occurs at plate boundaries that are associated with seafloor spreading?
Plate boundaries will collide with other plates with one plate sliding under
the other less dense plate creating Subduction. The plate underneath is
creating friction turning the rock into molten rock or lava and rises to the
surface creating volcanoes.
3. Describe three types of plate boundaries where volcanic eruptions can occur.
Divergent, The plates split allowing magma to rise to the surface.
Convergent, When an oceanic plate collides with a less dense plate
4. How are convection currents related to plate tectonics?
Scientist believes that convection currents transfer heat inside Earth that
provides energy to move the plates and causes so many features of the Earth.
5. Using figure 9 and a world map, determine what natural disasters might
occur in Iceland. Also determine what disasters might occur in Tibet. Explain
why some Icelandic disasters are not expected to occur in Tibet.
Iceland may split into two island and possible volcanic eruptions from being
above a mid-ocean ridge. Tibet disasters are Earthquakes from being on top
of a convergent plate boundary. The plate boundary activity is different
creating different disasters, Iceland’s plate boundary is diverging, and Tibet’s
plate boundary is converging.
Chapter 10 Assessment
1. Which layer of Earth contains the asthenosphere?
a) Crust
b) Mantle
c) Outer core
d) Inner core
2. What type of plate boundary is the San Andreas Fault part of?
a) Divergent
b) Subduction
c) Convergent
d) Transform
3. What hypothesis states that continents slowly moved to their present
positions on Earth?
a) Subduction
b) Seafloor spreading
c) Continental drift
d) Erosion
4. Which plate is subducting beneath the South American Plate to form the
Andes mountain range?
a) North American
b) African
c) Indo-Australian
d) Nazca
5. Which of the following features indicates that many continents are once near
Earth’s south pole?
a) Glacial deposits
b) Mid-ocean ridges
c) Volcanoes
d) Earthquakes
6. What evidence in rocks supports the theory of seafloor spreading?
a) Plate movement
b) Magnetic reversals
c) Subduction
d) Convergence
7. Which type of plate boundary is the Mid-Atlantic Ridge part of?
a) Convergent
b) Divergent
c) Transform
d) Lithosphere
8. What theory states that plates move around on the asthenosphere?
a) Continental drift
b) Seafloor spreading
c) Subduction
d) Plate tectonics
9. What forms when one plate slides past another plate?
a) Transform boundary
b) Divergent boundary
c) Subduction zone
d) Mid-ocean ridge
10. When oceanic plates collide, what volcanic landforms are made?
a) Folded mountains
b) Island arcs
c) Strike-slip faults
d) Mid-ocean ridge
11. Why do many earthquakes but few volcanic eruptions occur in Himalaya?
More Earthquakes happen in the Himalaya because the plate is converging
with another plate, but the plate isn’t and ocean plate, the plate is a
continental plate.
12. Glacial deposits often form at high latitudes near the pole. Explain why
glacial deposits have been found in Africa.
When Africa was in form with Pangaea, Africa was some where near the
South Pole of the Earth where Antarctica is now.
13. How is magnetism used to support the theory of seafloor spreading?
Magnetism was used to support the seafloor spreading theory by showing us
that over the past years every time the seafloor spreads when the iron in the
magma cools the floor has a new magnetic field. This was shown when
scientist measured the magnetic fields with a magnetometer and found high
ratings of magnetic fields.
14. Explain why volcanoes do not form along the San Andreas Fault.
The San Andreas Fault a strike-slip boundary sliding past each other with
little to no up or down movement. A strike-slip boundary does not push
against each other and slide under creating a volcano.
15. Explain why the fossil of an ocean fish found on two different continents
would not be good evidence of continental drift.
Ocean fish are salt-water fish that can go any where in the ocean and there
are too many places that the fish could have come from in the ocean.