Question 1

The theory of plate tectonics is a theory because it _____________.

Accepted Answer

The theory of plate tectonics cannot be directly proven, as we cannot directly observe the movement of tectonic plates over millions of years. However, the evidence supporting the theory is overwhelming, which is why it is widely accepted in the scientific community.

Question 2

If a geologist discovered coal in a modern-day cold,snowy location,he or she could conclude that _____________.

Accepted Answer

Coal forms from the remains of ancient plant material, so the discovery of coal in a modern-day location would suggest that the area had once been covered with swamps and/or jungles where this vegetation could have grown and been buried over time to eventually form coal deposits. The other choices (A, C, and D) do not have a clear connection to the formation of coal.

Question 3

According to Wegener,puzzle pieces are to a jigsaw puzzle as ____________ is/are to Pangaea.

Accepted Answer

Wegener compared the continents to pieces of a jigsaw puzzle that once fit together to form the supercontinent Pangaea.

Question 4

The apparent tendency of the north (or south)magnetic pole to vary in position over time is termed ____________.

Accepted Answer

The phenomenon described is known as polar wander, which refers to the slow movement of the Earth's magnetic poles over time. This movement can result in changes to magnetic declination, the angle between true north and magnetic north, and magnetic inclination, the angle the magnetic field lines make with the surface of the Earth. Dipole refers to a magnetic field that has two poles, such as the Earth's magnetic field.

Question 5

Which plant genus dominated glaciated regions during the Late Paleozoic and Early Mesozoic?

Accepted Answer

Glossopteris was a dominant plant genus during the Late Paleozoic and Early Mesozoic in glaciated regions, especially in Gondwana, which was centered on what is now India, Australia, and Antarctica. Its fossils have been found in these regions, indicating that it thrived in the cold and dry conditions that characterized these regions during that time.

Question 6

The magnetic field of Earth in the geologic past is ____________.

Accepted Answer

The answer of The magnetic field of Earth in the...

Question 7

Evidence for a united Pangaea comes from the fossil record of which type(s)of organisms?

Accepted Answer

The fossil record of plants, large terrestrial animals, and freshwater animals all provide evidence for a united Pangaea because they have been found on different continents that were once all connected. For example, fossils of the Glossopteris plant have been found on several different continents, indicating that they were all once part of the same landmass. Similarly, fossils of the same species of dinosaur have been found on different continents, further supporting the theory of continental drift and a united Pangaea. Finally, freshwater animals such as certain types of mosasaurs and crocodiles have also been found on different continents, indicating that there were once freshwater connections between these regions.

Question 8

Wegener's evidence for a united Pangaea was so compelling that virtually all geologists agreed with the idea of continental drift during his lifetime.

Accepted Answer

While some geologists were convinced by Wegener's evidence, many others were skeptical and the idea of continental drift did not become widely accepted until much later.

Question 9

Distinctive rock sequences on South America terminate at the Atlantic Ocean but reappear on the continent of ____________.

Accepted Answer

The distinctive rock sequences on South America terminate at the Atlantic Ocean but reappear on the continent of Africa. This suggests that the two continents were once joined together as part of the supercontinent of Gondwana.

Question 10

Without plate tectonics,we would not have _______________.

Accepted Answer

Without plate tectonics, there would be no plates in constant motion, which is necessary for the formation of mountains and the creation of new oceans. Therefore, all of the above choices are correct.

Question 11

Wegener proposed continental drift after he observed evidence from fossils,glacial deposits,and the fit of the continents that suggested all of the continents were once ____________.

Accepted Answer

Wegener proposed that all the continents were once combined to form a supercontinent he termed Pangaea, during the Late Paleozoic through the Mesozoic. He suggested that over time, the continents drifted apart to their current positions. His evidence included the fit of the continents, the distribution of fossils, and glacial deposits that were consistent with a former southern hemisphere location for some continents.

Question 12

The term and concept of sea-floor spreading (see figure below)was developed by _____________.

Accepted Answer

Sea-floor spreading was developed by Harry Hammond Hess and Robert Dietz in the 1960s based on their observations of magnetic anomalies on the ocean floor.

Question 13

Evidence that glaciers once covered an area might include ______________.

Accepted Answer

Till (unsorted glacial sediment) and striations (grooves or scratches on rocks created by glacial movement) are evidence of glacial activity. Backwash (water flowing back from the glacier) and grabens (down-dropped blocks of land between two faults) are not necessarily indicative of glacial activity.

Question 14

Currently,most geologists ____________.

Accepted Answer

Most geologists today agree that continental drift occurs, but the mechanisms that drive it were unknown in Wegener's time. The current understanding is that these mechanisms are at work in the ocean basins and upper mantle.

Question 15

Wegener's idea of continental drift was rejected by American geologists because ____________.

Accepted Answer

Wegener's theory lacked a valid mechanism to explain how the continents moved, which made it difficult for American geologists to accept it as a valid scientific theory.

Question 16

Consult the figure below.Abundant swamps led to the formation of coal during the Late Paleozoic in which of the following places?

Accepted Answer

The figure shows the distribution of coal deposits around the world during the Late Paleozoic. We can see that North America has a significant amount of coal deposits during this time, which suggests that abundant swamps existed in this region and led to the formation of coal. The other regions listed (India, southern Africa, South America) had relatively less coal deposits during this time period.

Question 17

Late Paleozoic glacial deposits are NOT found in which of the following places?

Accepted Answer

The answer of Late Paleozoic glacial deposits are NOT found...

Question 18

If we mentally align the continents to fit Wegener's concept of Pangaea,evidence of Late Paleozoic glacial deposits ____________.

Accepted Answer

Late Paleozoic glacial deposits are found in areas that are currently located near the equator, such as Africa and South America. This is difficult to explain in the modern continental configuration as these regions have warm climates due to their proximity to the equator. However, in the Pangaea configuration, these regions were located near the South Pole and could have experienced glacial conditions similar to those seen in Antarctica today. Therefore, the evidence of Late Paleozoic glacial deposits is much more readily explained in the Pangaea configuration than in the modern configuration.

Question 19

In Wegener's evidence for continental drift,continents were proposed to fit together,such as the east coast of South America with the __________________ and the upper west coast of Africa with the _______________.

Accepted Answer

The answer of In Wegener's evidence for continental drift,continents were...

Question 20

Limestone reefs and salt deposits are important rocks in the reconstruction of Earth history because they ____________.

Accepted Answer

The answer of Limestone reefs and salt deposits are important...

Quiz 3: Drifting Continents and Spreading Seas