Question 1

Which war was indirectly responsible for the development of the tools that made the theory of plate tectonics possible?

Accepted Answer

World War II indirectly led to the development of technology such as sonar and aerial photography, which were crucial in mapping the seafloor and understanding the geological processes that led to the theory of plate tectonics.

Question 2

Which of the following is not one of the major tectonic plates on the Earth's surface?

Accepted Answer

The Juan de Fuca Plate is a minor tectonic plate located off the west coast of North America and is not considered one of the major plates. The other options, North American, African, and Pacific plates, are all considered major tectonic plates.

Question 3

Which scientist developed the idea of continental drift?

Accepted Answer

Alfred Wegener developed the idea of continental drift in the early 20th century, proposing that continents were once joined together in a single landmass called Pangaea and gradually moved apart over millions of years.

Question 4

Continental crust is mainly composed of ________, whereas oceanic crust is mainly composed of ________.

Accepted Answer

Continental crust is primarily composed of granite, whereas oceanic crust mostly consists of basalt.

Question 5

The lithosphere is composed of the ________ and the rigid part of the ________.

Accepted Answer

The lithosphere is composed of the crust and the rigid, upper part of the mantle. The outer core and inner core are not part of the lithosphere as they are both part of the Earth's core, which is separate from the solid outer layers. The lower mantle is not part of the lithosphere either, as it is a more ductile layer that sits below the rigid lithosphere. Therefore, the best choice is D, which correctly identifies the crust and upper mantle as the components of the lithosphere.

Question 6

Continental rifting is occurring today in ________.

Accepted Answer

Continental rifting is currently occurring in the East African Rift valley, which stretches through Ethiopia and Kenya. The other options listed involve different types of tectonic activity, such as transform faulting (San Andreas Fault), failed rifts (mid-continent rift), or subduction zones (Cascadia subduction zone).

Question 7

In the mid-twentieth century, researchers dredging the seafloor could not find any materials older than ________.

Accepted Answer

The seafloor spreading theory and plate tectonics explain why materials older than about 180 million years are not found on the seafloor. This is due to the continuous process of oceanic crust being formed at mid-ocean ridges and destroyed at subduction zones.

Question 8

Which type of convergence will result in a continental volcanic arc?

Accepted Answer

A continental volcanic arc is formed by convergence of an oceanic plate and a continental plate. This convergence type is called oceanic-continental convergence. As the oceanic plate subducts beneath the continental plate, it melts and forms magma that rises to the surface, resulting in the formation of a volcanic arc on the continental plate.

Question 9

Why are the mid-ocean ridges higher in elevation than the surrounding ocean floor?

Accepted Answer

Mid-ocean ridges are higher in elevation than the surrounding ocean floor because the warmer material near the ridge is less dense, so it is more buoyant on the mantle. The elevated ridges are formed as magma rises from deep within the Earth's mantle and solidifies. The magma creates new crust that pushes the older, colder oceanic crust away from the ridge. As the new crust moves away from the ridge, it cools and sinks, creating the surrounding lower elevation ocean floor.

Question 10

Even before the proposal of continental drift, paleontologists recognized that some sort of land connection was needed to account for the identical fossil organisms found on multiple continents.Select the correct hypothesis or hypotheses these paleontologists developed.

Accepted Answer

Before the acceptance of continental drift, paleontologists proposed various hypotheses such as island stepping stones, transoceanic land bridges, and the use of floating debris as rafts to explain the distribution of identical fossil organisms across continents. These ideas were attempts to rationalize how species could have dispersed across vast oceans before the concept of continents moving closer together or apart (plate tectonics) was widely accepted.

Question 11

Think about what happens to the density of an oceanic plate as it ages and cools.How will the age and temperature of the subducting plate affect its angle of descent?

Accepted Answer

As an oceanic plate ages and cools, it becomes denser, which causes it to sink more easily into the mantle. This leads to a shallower angle of descent. The temperature of the subducting plate also affects its angle of descent, with warmer plates being less dense and therefore having a steeper angle of descent. Therefore, old, cool plates will have a shallow angle of descent, which is reflected in choice A.

Question 12

When the continents were assembled and mountain ranges were matched up, mountains in Scandinavia and the British Isles matched up perfectly with which North American mountain range?

Accepted Answer

The mountains in Scandinavia and the British Isles match up perfectly with the Appalachian Mountains in North America. This is due to the fact that these regions were once part of the same supercontinent, Pangaea, before they separated and moved apart.

Question 13

A ________ is a geographic low, which marks the location where oceanic lithosphere descends into the mantle.

Accepted Answer

A deep-ocean trench is a geographic low where oceanic lithosphere descends into the mantle, typically found at subduction zones where tectonic plates converge. Fold and thrust mountains are formed by the compressional forces of tectonic plate collisions, seismic zones are areas where earthquakes occur along faults, and mid-ocean rifts are where new oceanic crust is formed by volcanic activity at divergent plate boundaries.

Question 14

Although the jigsaw-puzzle fit of the southern continents was noted, opponents of continental drift argued that, even if continental displacement had occurred, a good fit between the continents today would be unlikely.What geologic evidence did they cite to support this claim?

Accepted Answer

Opponents of continental drift pointed out that wave erosion and coastal deposition have changed the shape of the continents over time, making a good fit unlikely even if they were once connected.

Question 15

What is the name of the supercontinent proposed by Alfred Wegener?

Accepted Answer

Alfred Wegener proposed the supercontinent Pangaea, which existed around 335 million years ago and began to break apart about 175 million years ago.

Question 16

Which type of convergence will result in a volcanic island arc?

Accepted Answer

The answer of Which type of convergence will result in...

Question 17

Which type of plate boundary accounts for the smallest percentage of all plate boundaries on the surface of the Earth?

Accepted Answer

Transform boundaries account for the smallest percentage of plate boundaries on Earth, as they only occur where two plates slide past each other horizontally. Divergent boundaries account for a larger percentage because they occur where two plates move away from each other, and convergent boundaries account for the largest percentage because they occur where two plates collide and can form various types of interactions such as subduction zones, mountain ranges, and volcanic arcs.

Question 18

In which decade was the theory of plate tectonics developed?

Accepted Answer

The theory of plate tectonics was developed in the 1960s through the work of geologists and geophysicists who conducted research on earthquake and volcanic activity, as well as ocean floor mapping.

Question 19

At a ________, an oceanic plate will be forced beneath another plate because of differences in density.

Accepted Answer

At a subduction zone, an oceanic plate will be forced beneath another plate because of differences in density.

Question 20

When considering evidence of glaciation on the southern continents, why did Wegener reject the explanation that the entire planet had experienced a period of extreme cooling?

Accepted Answer

Wegener rejected the idea of a global cooling period because there was geologic evidence, such as the existence of tropical swamps in the Northern Hemisphere at the same time, which indicated that the entire planet could not have been cold enough for glaciers to form in the southern continents.

Quiz 2: Plate Tectonics: a Scientific Revolution Unfolds