Chapter 2: Plate Tectonics

divergent plate boundaries

Boundary between tectonic plates in which the two plates move away from each other, and new crust is created between them

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.

ocean drilling

Drilling of the ocean floor from the mid ocean ridge toward the coast line

In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?

Due to tectonic activity, rocks on the ocean floor are continually recycled.

evidence of pangea

Fits like a puzzle, Fossil similarities, rock similarities, climate change

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.

Do fracture zones near transform boundaries play a role in plate motion?

No, fracture zones play no role in plate motion.

oceanic-oceanic convergence

Older oceanic plate is forced under the younger one creating subduction zone

convection

Process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler portions will sink.

transform fault examples

San Andreas fault

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

polar wandering

The apparent movement of the magnetic poles illustrated in magnetized rocks indicates that the continents have moved

When oceanic crust is subducted beneath continental crust, partial melting can occur. Which of the following best explains why the resultant magma rises through the crust toward the surface?

The magma is less dense than the surrounding solid rock.

At a convergent boundary, what is the relative motion of plates on each side of the boundary?

The plates move toward each other.

As oceanic crust is subducted, it melts, forming a body of magma. When this magma rises and interacts with the overlying continental crust, what change occurs in the composition of the magma?

The silica content of the magma increases.

paleomagnetism

The study of the alignment of magnetic minerals in rock,specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation

The formation of the Himalaya and the Tibetan Plateau was caused by which of the following events?

There was a collision of two pieces of continental crust at a subduction zone.

What role do transform boundaries play?

Transform boundaries connect other segments of plate boundaries.

What is the relationship between transform boundaries and mid-ocean ridges?

Transform boundaries connect segments of mid-ocean ridges.

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?

Warm, humid climate near the Equator

oceanic-continental convergence

When an oceanic and a continental plate collide, eventually the oceanic plate is subducted under the continental plate due to the high density of the oceanic plate.

Although new crust is being formed at divergent boundaries, Earth remains the same size. Which of the following statements provides the best reason for this? a. An equal volume of crust is being consumed at convergent boundaries. b. Magma continues to upwell at convergent boundaries. c. Earthquakes happen at divergent boundaries. d. Earth's gravitational field prevents it. e. Lava is extruded via volcanoes at convergent boundaries.

a

mantle plume

a mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity

What surface feature would you expect to form if both a hot spot and a tectonic plate are stationary?

a single volcano

magnetic reversal

a switch in the direction of Earth's magnetic field so that the magnetic north pole becomes the magnetic south pole and the magnetic south pole becomes the magnetic north pole.

hot-spot track

active hot-spot volcanoes commonly occur at the end of a chain of dead volcanoes.

When oceanic and continental crust collide at a subduction zone, one plate is forced under the other. The angle at which the subducting plate descends is due to which of the following factors? CHOOSE ALL THAT APPLY. a. the amount of water in the plate being subducted b. the density of the plate being subducted c. the composition of the plate being subducted d. the age of the plate being subducted e. the depth of the water over the plate being subducted

b, d

Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring. What type of plate boundary is this?

convergent

Crustal rifting is currently occurring in East Africa. Which of the following features would you expect to find there? a. Normal Faults b. Long, wide valley c. Lava flows d. All of the above are correct e. Only normal faults and long, wide valleys

d

Which tectonic boundary results when two tectonic plates pull apart from each other?

divergent

continental-continental convergence

neither is less dense; eventually one gives; thickening of continental crust; mountain building (i.e. Himalayas)

continental rifting

process that pulls a continent apart, usually in response to tension stress

Transform boundaries are classified under which type of fault?

strike-slip

Which of the following lithospheric plates is not included among the seven largest? the African plate the Philippine plate the Australian-Indian plate the Antarctic plate the South American plate

the Philippine plate

Earth's lithospheric plates are composed of crust and which of the following layers?

the outermost portion of the mantle

Divergent boundaries are not one, smooth ridge of separation. Instead, they are broken into a series of segments, with different segments of fault offset from others. What features allow for the offset of divergent boundaries?

transform faults

What surface feature provides evidence for the location of hot spots?

volcanoes within tectonic plates

As oceanic crust is subducted below continental crust, which of the following factors most directly drives the melting that will fuel volcanoes at the surface?

water

When will a hot spot volcano become extinct?

when the volcano is carried away from the hot spot by the tectonic plate

A continental volcanic arc is formed when which of the following conditions exists?

A piece of oceanic crust is subducted below continental crust.

pangea

A supercontinent containing all of Earth's land that existed about 225 million years ago.

transform plate boundaries

A tectonic plate boundary in which two plates slide past each other

convergent plate boundaries

A tectonic plate boundary where two plates collide, come together, or crash into each other.

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.

Which of the following processes can be observed at the margins of lithospheric plates? faulting earthquakes volcanoes mountain building All of the responses are correct.

All of the responses are correct