Chapter 2 - Plate Tectonics Flashcards
The late Paleozoic supercontinent is known as ________.
Pangaea
Which of the following energy sources is thought to drive the lateral motions of Earth’s lithospheric plates?
export of heat from deep in the mantle to the top of the asthenosphere
Pull-apart rift zones are generally associated with a ________ plate boundary.
divergent
New oceanic crust and lithosphere are formed at ________.
divergent boundaries by submarine eruptions and intrusions of basaltic magma
“Cooler, older, oceanic lithosphere sinks into the mantle at ________.”
subduction zones along convergent plate boundaries
Which one of the following is an important fundamental assumption underlying the plate tectonic theory?
Earth’s diameter has been essentially constant over time.
Deep-oceanic trenches are most abundant around the rim of the ________ ocean basin.
Pacific
Deep ocean trenches are surficial evidence for ________.
sinking of oceanic lithosphere into the mantle at a subduction zone
“The ________ is an example of an active, continent-continent collision.”
northward movement of India into Eurasia
A transform plate boundary is characterized by ________.
a deep, vertical fault along which two plates slide past one another in opposite directions
A very long-lived magma source located deep in the mantle is called a ________.
hot spot
Which one of the following most accurately describes the volcanoes of the Hawaiian Islands?
shield volcanoes fed by a long-lived hot spot below the Pacific lithospheric plate
“Which of the following statements apply to the asthenosphere, but not the lithosphere?”
zone in the upper mantle that deforms by plastic flowage
Today, ________ is in about the same geographic position as during late Paleozoic time.
Antarctica
Earth s surface is protected from solar wind and cosmic radiation by ____________.
Earth s magnetic field
The lithosphere is composed of the ____________.
crust and the uppermost part of the mantle
The youngest sea floor occurs ____________.
Along mid ocean ridges
A typical rate of seafloor spreading in the Atlantic Ocean is ________.
2 centimeters per year
True or False?
Wegener’s continental drift hypothesis was weakened because a viable mechanism for moving the continents was lacking.
True
True or False?
“The rate of seafloor spreading is, on the average, about one meter per year.”
False
True or False?
Earth’s radius and surface area are slowly increasing to accommodate the new oceanic crust being formed at mid-ocean ridges.
False
True or False?
“As the South Atlantic basin widens by seafloor spreading, Africa and South America are moving closer together.”
False
True or False?
“The oldest rocks of the oceanic crust are found in deep ocean trenches far away from active, mid-ocean ridges.”
True
True or False?
“In general, rocks of the continental crust are less dense than rocks of the oceanic crust.”
True
True or False?
The Himalayan Mountains are the tectonic product of a collision between India and Eurasia that began in Eocene time and still continues.
True
True or False?
The oldest rocks on the seafloor are much younger than the oldest rocks on the continents.
True
True or False?
Hawaii is the oldest island of the Hawaiian Island chain.
False
True or False?
“During various times in the geologic past, the polarity of Earth’s magnetic field has been reversed.”
True
True or False?
“During the geologic past, the magnetic field poles have generally been very close to Earth’s rotational poles.”
True
True or False?
The volcanoes of Hawaii are localized above a deep mantle hot spot; they are not part of the East Pacific oceanic ridge.
True
True or False?
Seafloor spreading rates can be estimated if the geologic ages of the magnetic field reversals are independently known.
True
True or False?
“An extensive, late Paleozoic glaciation affected southern India, southern Africa and southeastern South America.”
True
True or False?
“Iceland is a good example of an island arc, formed from an oceanic-oceanic plate collision.”
False
