supercontinent 250 million years ago
Pangaea
study of magnetism over geologic time
paleomagnetism
island arc
subduction zone
seafloor magnetic stripes
spreading center
trench
subduction zone
Which type of plate boundary is most closely associated with the formation of new ocean floor?
divergent
Earth's magnetic field switches polarity at irregular time intervals.
every 100,000 to several million years
A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity.
A record of Earth's magneti
Evidence for continental drift includes:
all of the above.
Fossils of ancient polar plants are currently found near the equator because the:
plants lived near the poles, but landmasses have drifted to current locations.
Climate distribution on Earth is primarily controlled by:
latitude.
A. Gondwanaland
B. Panamerica
C. Pangaea
D. Panthalassia
E. Tethys Sea
B. Panamerica
Regarding glacial ages, why is it unlikely that the entire world was covered by ice 300 million years ago?
Coal deposits from the same geologic age are now present in North America and Europe, which formed from the remains of vast tropical swamp plants.
How are Earth's geographic and magnetic axes oriented relative to each other?
Earth's geographic and magnetic axes are oriented at a slight angle to each other.
at the South Pole
the magnetic field of a bar magnet
parallel
about 500,000 years
toward the magnetic south pole
Earthquakes can occur only in the __________.
lithosphere
The book The History of Ocean Basins, which contained the idea of seafloor spreading, was written by geologist:
Harry Hess.
The seafloor magnetic pattern is best described as:
parallel to and symmetric about mid-ocean ridges.
Tectonic plates are pieces of the ________ that float on the more fluid ________ below.
lithosphere; asthenosphere
The magnetic north pole has remained very close to the geographic North Pole throughout all of geologic time.
false
New crust is formed at trenches and older crust is subducted at oceanic ridges.
alse
The magnetic field of the Earth reverses itself each time that magma erupts at a mid-ocean ridge.
false
Describe Earth's magnetic field, including how it has changed through time.
Earth's magnetic field is composed of invisible lines of magnetic force that originate within Earth and travel out into space. The polarity of the field has reversed itself throughout geologic time.
Describe seafloor spreading and why it was an important piece of evidence in support of plate tectonics.
Captain Hess suggested that new ocean crust was created at the mid-oceanic ridges and disappeared back into deep Earth at the trenches near the edges of ocean basins. This was an important piece of evidence in support of plate tectonics because it provide
When will magma rise to Earth's surface?
when the magma is less dense than adjacent rock
almost always
Heat from the mantle melts part of the lower crust.
Earth's crust is less dense than the mantle
Pressure from overlying crust forces mantle magmas through cracks to Earth's surface. These magma
Where are tectonic plates located?
at Earth's surface
divergent, convergent, and transform
Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries.
transform
hot spots
convergent boundaries
What is convection?
a cycle of moving material formed by the rise of less-dense material and the sinking of denser material
forces at subduction zones
n general, warmer materials are less dense, and colder materials are denser.
diffuse
a zone of upwelling material originatin
What type of volcano is Mount St. Helens?
Composite
A massive landslide
Moving magma had over-steepened the mountain slopes.
A&D
2.8 cubic kilometers of rock
The Mid-Atlantic Ridge is an example of a:
divergent plate boundary.
Which of the following is characteristic of oceanic-continental convergent plate boundaries?
andesitic volcanoes
Which of the following is characteristic of continental-continental convergent plate boundaries?
uplifted mountain ranges
A. divergent plate boundary
B. oceanic-continental convergence
C. oceanic-oceanic convergence
D. transform plate boundary
E. hot spot
hot spot
A. hydrothermal vents
B. island arc
C. mountains
D. oceanic trench
E. volcanoes
vents
A. transform fault
B. Sand Andreas Fault
C. oceanic transform fault
D. Juan de Fuca Ridge
E. Mariana Trench
trench
Deep-sea trenches are found at convergent plate boundaries.
truth
Water depth decreases as you move away from the mid-ocean ridge.
flasw
Convergent plate boundaries occur when tectonic plates move in opposite directions.
false
Do most lithospheric plates contain both oceanic- and continental-type crust?
Yes, most lithospheric plates contain both oceanic- and continental-type crust
Iceland is located on what type of plate boundary?
Divergent
The Hawaiian Islands are located where the Pacific plate is:
moving over a hot spot or mantle plume.
volcanoes on the seafloor that are flat-topped because of wave erosion are called:
tablemounts
The first scientist to propose the origin of coral reefs based upon subsidence (sinking) of volcanic islands was:
Charles Darwin
A. Aleutian Islands
B. Canary Islands
C. Galapagos Islands
D. Hawaiian Islands
E. Iceland
A. Aleutian
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
The majority of the world's hotspots are associated with plate boundaries
false
Charles Darwin was the first person to propose a hypothesis on the origin of coral reefs.
true
ow is the age distribution pattern of the Hawaiian Islands-Emperor Seamount chain explained by the position of the Hawaiian hot spot?
The volcanoes in the Hawaiian Island-Emperor Seamount chain get progressively older as one heads northwestward from Hawaii. These age relationships suggest that the Pacific Plate has been steadily moving northwestward, while the underlying mantle plume ha
How can plate tectonics be used to help explain the difference between a seamount and a tablemount?
A seamount is a volcano with a cone-shaped top, whereas a tablemount is a volcano with a flattened top. Though both of these features originate at the crest (and topographic high) of the mid-ocean ridge, a tablemount has been subject to wave erosion when
The study of historical changes of continental shapes and positions is called:
paleogeography.
Loihi is __________.
the newest Hawaiian volcano
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, h
About 12,230,000 years
A researcher interested in the vertical zonation of oceanic lithosphere would want to study __________.
ophiolites
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
Of the following statements about Earth's magnetic field, which is/are true?
The magnetic field is oriented horizontal (parallel) to Earth's surface at the magnetic equator.
Of the following statements about ocean crust, which is/are true?
Ocean crust is created at the mid-ocean ridge.
What do all plate boundaries have in common? Select only one answer.
They are all associated with zones of earthquakes.
Of the following statements about nemataths and volcanic arcs, which is/are true?
A volcanic arc is associated with a convergent plate boundary.