Oceanography Chapter 2
Match the term with the appropriate phrase. supercontinent 250 million years ago
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.
What is the relationship between the crust and lithosphere?
The crust is part of the lithosphere.
Which hypothesis best explains the continuous bend in the Hawaiian Islands-Emperor Seamount chain?
The direction of plate motion shifted over time over a stationary mantle plume (hot spot).
How often does the Earth's magnetic field switch polarity?
every 100,000 to several million years
What is a fault?
fractures along which rocks move
Where do coral reefs exist with sea mounts
in tropical latitudes
Climate distribution on Earth is primarily controlled by:
latitude.
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
Where would you expect to see alternating bands of rock with different magnetic polarities?
on both sides of the mid-ocean ridge
Ophiolites
pieces of oceanic crust thrusted onto continental crust
Fossils of ancient tropical plants are currently found near the poles because the:
plants lived in the tropics, but landmasses have drifted to current locations.
Match the term with the appropriate phrase. trench
subduction zones
What is a tablemount?
A seamount that grew above sea level, experienced wave erosion, and is now inactive.
Examine the five words and/or phrases and determine the relationship among the majority of words/phrases. Please identify the word and/or phrase that does NOT fit the pattern. Enter only the letter of the answer (caps, no period, and not the full entry) in the field below. A. Gondwanaland B. Panamerica C. Pangaea D. Panthalassa E. Tethys Sea
B
The study of historical changes of continental shapes and positions is called:
paleogeography.
Sea floor spreading along the axis of an oceanic ridge results in symmetrical patterns of all of the following EXCEPT ______________.
the location of subduction zones
In general, when will melted rock in the mantle rise?
almost always
Where is the youngest ocean floor found?
along the crest of mid-ocean ridges
Which of the following mountain ranges are examples of continental arcs?
andes and cascades
Which type of force is responsible for normal strike-slip formation?
shear force
Match the term with the appropriate phrase. seafloor magnetic stripes
spreading center
Which type of fault has no vertical motion of rocks associated with it?
strike-slip fault
Match the term with the appropriate phrase. island arc
subduction zone
Earthquakes can occur only in the __________.
lithosphere
Tectonic plates are pieces of the ________ that float on the more fluid ________ below.
lithosphere; asthenosphere
volcanoes on the seafloor that are flat-topped because of wave erosion are called:
tablemounts
Which type of force is responsible for normal fault formation?
tensional force
The following set of observations describes an actual body of water. Evaluate these statements and determine the evolutionary stage of an ocean basin based upon the following characteristics: Lacks a mid-ocean ridge Deep ocean basin is present Early signs of mountain formation Volcanic island arc and trench absent
terminal
The Hawaiian Islands are located where the Pacific plate is:
moving over a hot spot or mantle plume.
Complete this statement: Divergence is to moving away as convergence is to _______
moving toward
A researcher interested in the vertical zonation of oceanic lithosphere would want to study __________.
ophiolites
Match the term with the appropriate phrase. study of magnetism over geologic time
paleomagnetism
The seafloor magnetic pattern is best described as:
parallel to and symmetric about mid-ocean ridges.
Convergent plate boundaries occur when tectonic plates move away from each other.
False
New crust is formed at trenches and older crust is subducted at oceanic ridges.
False
The magnetic field of the Earth reverses itself each time that magma erupts at a mid-ocean ridge.
False
The magnetic north pole has remained very close to the geographic North Pole throughout all of geologic time.
False
How are felsic magmas formed?
Heat from the mantle melts part of the lower crust.
Examine the five words and/or phrases and determine the relationship among the majority of words/phrases. Please identify the word and/or phrase that does NOT fit the pattern. Enter only the letter of the answer (caps, no period, and not the full entry) in the field below. A. hydrothermal vents B. island arcs C. tall, folded mountain belts D. oceanic trenches E. large volcanoes caused by subduction
A
Of the following statements about Earth's magnetic field, which is/are true? The magnetic field is oriented vertical relative to Earth's surface at the south magnetic pole. The magnetic field is oriented vertical relative to Earth's surface at the north magnetic pole. Earth's magnetic field has varying dips around the world that range from vertical to horizontal, depending on latitude. The locations of Earth's magnetic poles have moved through time and have even reversed in polarity. The magnetic field is oriented horizontal (parallel) to Earth's surface at the magnetic equator.
ALL
The first scientist to propose the origin of coral reefs based upon subsidence (sinking) of volcanic islands was:
Darwin
Iceland is located on what type of plate boundary?
Divergent
Examine the five words and/or phrases and determine the relationship among the majority of words/phrases. Please identify the word and/or phrase that does NOT fit the pattern. Enter only the letter of the answer (caps, no period, and not the full entry) in the field below. A. divergent plate boundary B. oceanic-continental convergence C. oceanic-oceanic convergence D. transform plate boundary E. hot spot
E
Examine the five words and/or phrases and determine the relationship among the majority of words/phrases. Please identify the word and/or phrase that does NOT fit the pattern. Enter only the letter of the answer (caps, no period, and not the full entry) in the field below. A. transform fault B. San Andreas Fault C. oceanic transform fault D. Mendocino Fracture Zone E. Mariana Trench
E
How do mafic volcanic rocks get to Earth's surface?
Pressure from overlying crust forces mantle magmas through cracks to Earth's surface. These magmas erupt out of volcanoes, cool, and solidify into rock.
What do all plate boundaries have in common? Select only one answer.
They are all associated with zones of earthquakes.
Areas of intense volcanic activity that remain in more or less the same location over long periods of geologic time and are unrelated to plate boundaries are called hotspots.
True
Charles Darwin was the first person to propose a hypothesis on the origin of coral reefs.
True
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
Nematath
chain of extinct volcanoes that is progressively older as one travels away from a hotspot
Which type of force is responsible for reverse fault formation?
compressional force
Which type of plate boundary is most closely associated with the formation of new ocean floor?
divergent
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 caused the formation of the Himalayas?
the collision of India with Asia
What are rocks below and above a fault called?
the footwall below and the hanging wall above
Loihi is __________.
the newest Hawaiian volcano
What was Panthalassa?
the single ocean that existed after the Pangaean supercontinent formed
Andesitic volcanoes
type of volcanic rock in the andes
Which of the following is characteristic of continental-continental convergent plate boundaries?
uplifted mountain ranges
Of the following statements about ocean crust, which is/are true? Ocean crust is destroyed at transform faults. Ocean crust is destroyed at deep sea trenches. Ocean crust is created at transform faults. Ocean crust is destroyed at the mid-ocean ridge. Ocean crust is created at deep sea trenches. Ocean crust is created at the mid-ocean ridge.
2 and 6
Examine the five words and/or phrases and determine the relationship among the majority of words/phrases. Please identify the word and/or phrase that does NOT fit the pattern. Enter only the letter of the answer (caps, no period, and not the full entry) in the field below. A. Aleutian Islands B. Canary Islands C. Galapagos Islands D. Hawaiian Islands E. Iceland
A
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.
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.
Of the following statements about nemataths and volcanic arcs, which is/are true? A volcanic arc is associated with a convergent plate boundary. In a volcanic arc, any of the volcanoes can be active at any time. Nemataths and volcanic arcs are both the result of volcanic activity. In a nematath, the age of the volcanoes progressively decreases as you move closer to the volcanic source. A nematath is created by a hotspot.
ALL
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
What is a seamount?
An active volcano that occurs along the crest of the mid-ocean ridge.
Which of the following is characteristic of oceanic-continental convergent plate boundaries?
Andesitic volcanoes
What is the difference between a barrier reef and an atoll?
Barrier reefs surround an inactive volcano emerging above sea level, while atolls surround the previous location of a submerged volcano.
Which of the following is the main reason that Earth has a magnetic field?
Convection in the liquid iron-nickel outer core generates a magnetic field.
Which of the following statements about coral reefs and seamounts is most accurate?
Coral reefs at the ocean surface grow away from seamounts over time
In general, why does Earth's crust sit on top of the mantle?
Earth's crust is less dense than the mantle.
Which of the following statements about Earth's magnetic field is most accurate?
Earth's magnetic field switches polarity at irregular time intervals.
The majority of the world's hotspots are associated with plate boundaries.
False
Water depth decreases as you move away from the mid-ocean ridge.
False
Which is the correct order of coral reef development near seamounts?
Fringing reef, barrier reef, atoll
Which supercontinent contained Africa and South America?
Gondwanaland
The book The History of Ocean Basins, which contained the idea of seafloor spreading, was written by geologist:
Harry Hess.
What were the names of the two smaller super continents that formed when Pangaea broke apart?
Laurasia and Gondwanaland
Which of the following statements about tectonic plates is true? Few tectonic plates contain both oceanic and continental lithosphere. Most tectonic plates contain both oceanic and continental lithosphere. All tectonic plates contain both oceanic and continental lithosphere. No tectonic plates contain both oceanic and continental lithosphere.
Most tectonic plates contain both oceanic and continental lithosphere.
Why do coral reefs at the ocean surface grow away from seamounts over time?
Seamounts subside as tectonic plates move. Coral reefs grow away from the seamount in order to stay near the sunlight.
What is the relationship between the mantle and the lithosphere?
Some of the mantle is contained within a smaller layer called the lithosphere.
Deep-sea trenches are found at convergent plate boundaries.
True
The Wilson Cycle uses plate tectonic processes to show the life cycles of ocean basins during their growth, formation, and destruction over geologic time.
True
What is the relationship between continent edges and plate boundaries?
Very few plate boundaries follow the edges of continents.
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 provides evidence for the location of hot spots?
volcanoes within tectonic plates
When will magma rise to Earth's surface?
when the magma is less dense than adjacent rock
When will a hot spot volcano become extinct?
when the volcano is carried away from the hot spot by the tectonic plate