Oceanography ch. 2
What caused the formation of the Himalayas?
The collisions of India with Asia
Which type of plate boundary exists between India and Asia today?
a convergent boundary
which type of force is responsible for reverse fault formation
compressional force
How often does the Earth's magnetic field switch polarity?
every 100,000 to several million years
water depth decreases as you move away from the mid-ocean ridge
false
Where do coral reefs exist with sea mounts
in tropical latitudes
which type of force is responsible for normal strike-slip formation
shear force
Volcanoes on the seafloor that are flat-topped because of wave erosion are called
tablemounts
which type of force is repsonsible for nomal fault formation
tensional force
What was Panthalasse
the single ocean that existed after the Pangaen super continent formed
Deep-sea trenches are found at convergent plate
true
What is the difference between a barrier reef and an atoll?
Barrier reeds surround an inactive volcano emerging above sea level, while atolls surround the previous location of a submerged volcano
The seafloor magnetic pattern is best described as
Parallel to and symmetric about mid-ocean ridges
Which of the following statements is most accurate? landmass
Prior to 30 million years ago, Tibet was a much thinner landmass than it is today
In general, why does Earth's crust sit on top of the mantle?
Earth's crust is less dense than the mantle
In general, when will melted rock in the mantle rise?
almost always
what were the names of the two smaller super continents that formed when Pangaea broke apart?
Laurasia and Gondwanaland
Earthquakes can occur only in the
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 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
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
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)
Loihi is
the newest Hawaiian volcano
Which of the following is characteristic of continental-continental convergent plate boundaries?
uplifted mountain ranges
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
What is a volcanic arc?
A row of volcanoes that forms on the overriding plate near a subduction zone
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 mountain ranges are examples of continental arcs?
Andes and Cascades
Where would you expect to see alternating bands of rock with different magnetic polarities
on both sides of the mid-ocean ridge
A researcher interested in the vertical zonation of oceanic lithosphere would want to study
ophiolites
The study of historical changes of continental shapes and positions is called
paleogeography
What do all plate boundaries have in common
They are all associated with zones of earthquakes
When will magma rise to Earth's surface?
When the magma is less dense than adjacent rock
Did any subduction occur during the collision of india and Asia?
Yes; ocean basic between these two continents subducted under Asia
Match the term with the appropriate phrase: island arc
subduction zone
Match the term with the appropriate phrase: trench
subduction zone
What are rocks below and above a fault called
the football below and the hanging wall above
which type of fault has no vertical motion of rocks associated with it
strike-slip fault
Sea floor spreading along the axis of an oceanic ridge results in symmertical patterns of all the following except
the location of subduction zones
Of the following statements about nemataths and volcanic arcs which are true
- Nemataths and volcanic arcs are both the result of volcanic activity. - A volcanic arc is associated with a convergent plate boundary. - A nematath is created by a hotspot. - In a nematath, the age of the volcanoes progressively decreases as you move closer to the volcanic source. - In a volcanic arc, any of the volcanoes can be active at any time.
What was Pangaea
A supercontinent that began to break apart about 200 million years ago
Iceland is located on what type of plate boundary
Divergent
Which supercontinent contained Africa and South America
Gondawanaland
The book The History of Ocean Basins, which contained the idea of seafloor spreading, was written by geologist
Harry Hess
How are felsic magmas formed?
Hear from the mantle melts part of the lower crust
What is the relationship between the crust and the lithosphere?
The crust is part of the lithosphere
What surface feature provides evidence for the location of hot sports?
volcanoes within tectonic plates
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
Which of the following statements is most accurate? countries
A moving India collided with a stationary Asia about 30 million years ago
What is a tablemount?
A seamount that grew above sea level, experienced wave erosion, and is now inactive
Evidence for continental drift includes
All of the above
The hawaiian Islands are located where the Pacific plate is
Moving over a hot spot of mantle plume
Of the following statements about ocean crust which are true?
Ocean crust is created at the mid-ocean ridge
Which geologic features are associated with convergent boundaries?
Ocean trenches and volcanoes
Match the term with the appropriate phrase: supercontinent 250 million years ago
Pangaea
Fossils of ancient tropical plants are currently found near the poles because the
Plants lives in the tropics, but landmasses have drifted to current locations
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
Which mountain belt lies to the north of India?
The Himalayas
What is the relationship between the crust and lithosphere?
The crust is part of the lithosphere
Which of the following statements about Earth's magnetic field is most accurate?
Earth's magnetic field switches polarity at irregular time intervals
Convergent plate boundaries occur when tectonic plates move away from each other
False
New crust is formed at trenches and older rust 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 the geologic time
False
The majority of the wold's hotspots are associated with plate boundaries
False
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 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 super continent formed
Where is the youngest ocean floor found?
along the crest of mid-ocean ridges
Which of the following is characteristic of oceanic-continental convergent plate boundaries?
andesitic volcanoes
Which type of plate boundary is most closely associated with the formation of new ocean floor?
divergent
Platers move apart at ____ boundaries, move together at ____ boundaries, and move side-by-side at _____ boundaries
divergent/convergent/transform
Which geologic features are associated with divergent boundaries
mid-ocean ridges and continental rift valleys
Complete this statement: Divergence is to moving away as convergence is to ____
moving toward
Match the term with the appropriate phrase: study of magnetism over geologic time
paleomagnetism
What is the relationship between the mantle and the lithosphere?
some of the mantle is contained within a smaller layer called the lithosphere
Match the term with the appropriate phrase: seafloor magnetic stripes
spreading center
When will a hot spot volcano become extinct
when the volcano is carried away from the hot spot by the tectonic plate
Of the following statements about Earth's magnetic field, which are true
- 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. - 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 magnetic field is oriented vertical relative to Earth's surface at the south magnetic pole.
The first scientist to propose the origin of coral reefs based upon subsidence (sinking) of volcanic islands was
Charles Darwin
Which of the following is the main reason that Earth has a magnetic field?
Convection in the liquid iron-nickel outercore 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
Which is the correct order of coral reef development near seamounts
Fringing reef, barrier reef, atoll
Which of the following statements about tectonic plates is true?
Most tectonic plates contain both oceanic and continental lithosphere
Climate distribution on Earth is primarily controlled by
Lattitude
The cities of Los Angeles and San Francisco, CA, are about 380 miles apart. Plate motion along the San Andreas Fault is about five centimeters per year. If the Los Angeles Dodgers and the San Francisco Giants continue to play at their current locations, how long will it be before their games will constitute a cross-town rivalry?
about 12,230,000
What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary
a single volcano
Tectonic plates are pieces of the ____ that float on the more fluid ____ below
a. Lithosphere b. Asthenosphere
The following set of observation describes an actual body of water. Evaluate these statements and determine the evolutionary stage of ocean basin based upon the following characteristics
a. lacks a mid-ocean ridge b. deep ocean basin is present c. early signs of mountain formation d. volcanic island arc and trench absent -terminal
The Mid-Atlantic ridge is an example of a
divergent plate boundary
New crust is formed at trenches and older crust is subducted at oceanic ridges
false
The magnetic north pole has remained very close to the geographic North Pole throughout all of geologic time
false
In general what are the Himalayan mountains composed of?
folded and faulted rock
Complete this statement: Divergence is to moving away as convergence is to
moving toward
Why didn't india subduct under Asia
the two continents have similar densities