Chapter 3-Natural Disasters
How are normal polarity and reverse polarity of Earth's magnetic field different?
A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity.
The Alpine Fault of New Zealand is an example of ________ plate boundary.
A continental transform
The San Andreas Fault is an example of ________ plate boundary.
A continental transform
The Alps are an example of ________ plate boundary.
A continental-continental convergent
The Himalaya Mountains are an example of ________ plate boundary.
A continental-continental convergent
The East Africa Rift Valleys are an example of ________ plate boundary
A continental-continental divergent
The Red Sea is an example of ________ plate boundary.
A continental-continental divergent
In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?
A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.
Which of the following is an example of an oceanic-oceanic convergent plate boundary?
Aleutian Islands
What is the relationship between the mantle and the asthenosphere?
All of the asthenosphere is contained within a larger layer called the mantle.
What is the relationship between the crust and the lithosphere?
All of the crust is contained within a larger layer called the lithosphere
The Eltanin Fault is an example of ________ plate boundary.
An oceanic transform
The Mendocino Fault is an example of ________ plate boundary.
An oceanic transform
The Peru Chile Trench is an example of ________ plate boundary.
An oceanic-continental convergent
The Aleutian Islands are an example of ________ plate boundary.
An oceanic-oceanic convergent
The Mariana Trench is an example of ________ plate boundary
An oceanic-oceanic convergent
The Mid-Atlantic Ridge is an example of ________ plate boundary.
An oceanic-oceanic divergent
Which of the following is an example of an oceanic-continental convergent plate boundary?
Andes Mountains
Which of the following is characteristic of oceanic-continental convergent plate boundaries?
Andesitic volcanoes
What causes an earthquake such as the one that occurred in San Francisco in 1906?
As plates move, stress builds up at the boundary. When the boundary eventually snaps, energy is released as an earthquake.
Which type of plate boundary is most closely associated with the formation of new ocean floor?
Divergent
Which of the following statements about tectonic plates is true?
Most tectonic plates contain both oceanic and continental lithosphere.
Complete this statement: Divergence is to moving away as convergence is to
Moving toward
Which of the following regions was not part of the large Southern Hemisphere continent of Gondwana?
North America
Where would you expect to see alternating bands of rock with different magnetic polarities?
On both sides of the mid-ocean ridge
Which of the following is an example of a continental-continental divergent plate boundary?
Red Sea
Intervals of paleomagnetic ___________ is/are characterized by the alignment of the magnetic south pole and the geographic north pole.
Reversed Polarity
Which of the following is an example of a continental transform plate boundary?
San Andreas Fault
Although all areas of seafloor spreading have tectonic plates diverging and molten magma upwelling from below, not all areas of seafloor spreading are the same. The rate of spreading can affect the shape of the seafloor and the location of molten rock.
Slow spreading rate Top middle- rift valley Top Right- poorly- developed magma chamber Rapid Speading rate Top left- Swell Top Right- Well- Developed magma chamber Bottom middle- Diverging plates
How were scientists able to determine the date of the magnetic reversals during seafloor spreading?
Small marine fossils in deep-sea sediments give the age of the portions of the seafloor
What is the relationship between the mantle and the lithosphere?
Some of the mantle is contained within a smaller layer called the lithosphere.
What evidence supports that the glaciers on the southern continents were once part of a single, massive ice sheet?
Striations **Striations are scratches or grooves created by glacial debris as it moves. The striations found on the southern continents all radiate from the center of the south part of Pangaea.
What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?
The Earth would increase in volume.
Late Paleozoic sedimentary rocks often contain extensive coal seams that were used to support the existence of Pangaea. What would the climate have been at that time and at the location where the coal deposits were formed, and what would it indicate about the continent's past latitude?
The climate would have been a warm, humid climate near the Equator.
When matching up once-joined continents such as South America and Africa, the coastlines do not fit together as nicely as the continental shelves. Why might this be the case?
The continental shelves are the edges of the continent. The shoreline simply shows where the sea level is in relation to topography.
What is the relationship between the crust and lithosphere?
The crust is part of the lithosphere.
What prompted the first widespread mapping of the ocean floor?
The importance of submarine warfare during World War II
As Heezen and Tharp interpreted the ocean depth data, they identified what unusual feature that hinted at continental drift?
The oceanic ridges have a cleft, or rift, in the middle rather than a peak.
What did the maps of the ocean floor produced by Bruce Heezen and Marie Tharp reveal about seafloor topography?
There are ridges in the middle of the ocean basin floors.
Why did Heezen and Tharp have to do "inspired guessing" when creating their maps of the ocean floor?
There were gaps in the data that were used to make the map because the tracks of the ships collecting the data were widely spaced.
Which of the following statements about Earth's magnetic field is most accurate?
Earth's magnetic field switches polarity at irregular time intervals.
Which of the following is an example of an oceanic-oceanic divergent plate boundary?
East Pacific Rise
Seafloor depth was first determined by what remote sensing technology?
Echo Sounder
How often does the Earth's magnetic field switch polarity?
Every 100,000 to several million years
What accounts for most tectonic plate motion?
Forces at subduction zones account for most tectonic plate motion.
How was the fossil record of ancient life used to support Wegener's hypothesis about Pangaea?
Fossils of identical organisms were found on several continents, indicating the continents were once joined.
Which supercontinent contained Africa and South America?
Gondwanaland
Which of the following is an example of a continental-continental convergent plate boundary?
Himalaya Mountains
What is the relationship between temperature and density?
In general, warmer materials are less dense, and colder materials are more dense.
Since the breakup of Pangaea approximately 165 million years ago, a new supercontinent cycle has begun with the collision of which of the following continents?
India and Asia
How is information about magnetic fields recorded in rocks?
Iron particles in magnetically susceptible minerals within basaltic lava align with the magnetic field of the Earth while the lava is still liquid and then freeze in position when the lava solidifies.
Match the term with the appropriate phrase. Drag the terms on the left to the appropriate blanks on the right. (Terms can be used more than once.)
Island Arc- Subduction zone Mid-ocean ridge- Spreading center Seafloor magnetic stripes- Spreading center Seafloor spreading - spreading center Trench- Subduction zone
What were the names of the two smaller super continents that formed when Pangaea broke apart?
Laurasia and Gondwanaland
Which of the following is an example of an oceanic transform plate boundary?
Mendocino Fault
Which of the following is characteristic of continental-continental convergent plate boundaries?
Uplifted mountain ranges
What is the relationship between continent edges and plate boundaries?
Very few plate boundaries follow the edges of continents.
Which of the following is characteristic of oceanic-oceanic convergent plate boundaries?
Volcanic island arcs
The Gulf of California is an example of ________ plate boundary
a continental-continental divergent
The bend in the stone walls in the town of Hollister, California are a result of
a fault creep along the Calaveras Fault
What was the Tethys Sea?
a piece of the Panthalassa Ocean that existed after the Pangaean supercontinent formed
What is a volcanic arc?
a row of volcanoes that forms on the overriding plate near a subduction zone
What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary?
a single volcano
What was Pangaea?
a supercontinent that began to break apart about 200 million years ago
what is a plume
a zone of upwelling material originating at the outer core mantle boundary
Where is the youngest ocean floor found?
along the crest of mid-ocean ridges
The Andes Mountains are an example of ________ plate boundary.
an oceanic-continental convergent
The East Pacific Rise is an example of ________ plate boundary.
an oceanic-oceanic divergent
Which of the following mountain ranges are examples of continental arcs?
andes and cascades
Which of the following techniques can be used to recreate the configuration of supercontinents that existed before Pangaea?
apparently wandering polar paths
What geologic process initiated the breakup of Pangaea approximately 165 million years ago?
continental rifting
Which of the following terms best characterizes upwelling in the asthenosphere?
diffuse
The Mid-Atlantic Ridge is an example of a:
divergent plate boundary
Plates move apart at __________ boundaries, move together at __________ boundaries, and move side-by-side at __________ boundaries
divergent/convergent/transform
What features at the surface provide evidence of plumes?
hot spots
The San Andreas Fault
is a continental transform fault
Earth's outer layer is composed of seven dominant plates. What is the name of this rigid outer layer?
lithosphere
Which geologic features are associated with divergent boundaries?
mid-ocean ridges and continental rift valleys
Which geologic features are associated with convergent boundaries?
ocean trenches and volcanoes
The offset of Wallace Creek is caused by
right-lateral movement along the San Andreas strike-slip fault
Deep ocean trenches are associated with:
subduction zones
What caused the formation of the Himalayas?
the collision of India with Asia
What was Panthalassa?
the single ocean that existed after the Pangaean supercontinent formed
What type of plate interaction produces the San Andreas Fault?
transform(sliding past each other)
What surface feature provides evidence for the location of hot spots?
volcanoes within tectonic plates
When will a hot spot volcano become extinct?
when the volcano is carried away from the hot spot by the tectonic plate
Using the figure above, when was the last time the Earth had a magnetic reversal?
700,000 years
The seafloor rocks (oceanic lithosphere) formed at centers of seafloor spreading are transported away from the mid-ocean ridges. As time passes, oceanic lithosphere moves slowly away from the spreading center at which it formed as plates continue to move and new lithosphere forms at the spreading center. In the map below, the age of oceanic lithosphere is denoted with colors. Red indicates the youngest seafloor, which is less than two million years old. Dark blue indicates the oldest seafloor, which is over 144 million years old. Sedimentary rocks of the continental shelves are colored in light blue and are not considered part of the oceanic lithosphere. Rank from oldest to youngest
C E A D B
Which of the following statements best describes Wegener's idea of continental drift?
Continents were formerly in different positions on the Earth and have shifted to their present locations over time.
What is convection?
Convection is a cycle of moving material formed by the rise of less-dense material and the sinking of denser material.
Which part of the Earth is responsible for generating the planet's magnetic field?
Core