Question 1

When did the great southern hemisphere glaciation of Pangaea occur?

Accepted Answer

The great southern hemisphere glaciation of Pangaea occurred during the Permian Period, which was approximately 299-252 million years ago.

Question 2

The ________ of the geologic time scale occurs within the time of Earth's most recent "Ice Age."

Accepted Answer

The Pleistocene Epoch occurred from about 2.6 million years ago to 11,700 years ago, which is within the time of Earth's most recent "Ice Age." The other options are not directly associated with this time period.

Question 3

The only true modern-day, continental ice sheets are on Antarctica and in the Canadian Arctic.

Accepted Answer

The only true modern-day, continental ice sheets are found in Antarctica and Greenland, not in the Canadian Arctic.

Question 4

Prior to its sudden emptying down the St.Lawrence around 11,000 years ago, ________ was the largest lake in North America.

Accepted Answer

Lake Agassiz was the largest lake in North America before it emptied down the St. Lawrence River around 11,000 years ago. The other options are not correct as Great Bear Lake is the eighth largest lake in North America, Maligne Lake is relatively small, and Lake Winnipeg is the sixth largest lake in Canada but not the largest in North America.

Question 5

Except for vestigial ice fields, Alpine glaciers are usually many times longer than they are wide.

Accepted Answer

Alpine glaciers are typically long and narrow, with lengths that can be many times greater than their widths. Vestigial ice fields, on the other hand, are small remnants of once-larger glaciers and may not exhibit this characteristic shape.

Question 6

Alpine glaciers form in pre-existing stream valleys at high altitudes.

Accepted Answer

Alpine glaciers form in stream valleys where the overall topography is steep and there is sufficient snow accumulation to flow downhill and accumulate more snow. This typically occurs at high altitudes or higher latitudes where the climate is cold enough to sustain glaciers.

Question 7

Because ice floats on seawater, coastal outlet and piedmont glaciers seldom erode much below the elevation of sea level at the times the glaciers are active.

Accepted Answer

This is true because as ice floats on seawater, the weight of the ice is supported by the water underneath it. This means that glaciers cannot erode the sea floor below sea level, which is why coastal outlet and piedmont glaciers usually won't erode much below that level.

Question 8

________ developed and promoted the first comprehensive mathematical model that periodic variations in the geometry of Earth's orbit (eccentricity, obliquity, precession)were responsible for climatic oscillations of 1000 to 100,000 years.

Accepted Answer

Milutin Milankovitch developed and promoted the Milankovitch cycles, which propose that changes in Earth's orbit are responsible for changes in climate over long periods of time.

Question 9

How long ago was the glacial maximum of the last Ice Age?

Accepted Answer

The glacial maximum of the last Ice Age occurred approximately 20,000 years ago, during the Late Pleistocene era. This was the period when the ice sheets were at their maximum extent and the average global temperature was about 4-5 degrees Celsius colder than it is today.

Question 10

During the retreat of the last ice sheets, how long ago did modern sea level become established?

Accepted Answer

Modern sea level became established around 6000 years ago, following the retreat of the last ice sheets. This period marks the end of significant sea-level rise associated with the melting of the ice sheets from the last Ice Age.

Question 11

Which one of the following could not have significantly affected climatic variations, and advances and retreats of ice sheets, during the Pleistocene Epoch?

Accepted Answer

Gradual movements of Earth's tectonic plates occur over millions of years and are too slow to cause the relatively rapid climatic changes and ice sheet advances and retreats seen during the Pleistocene Epoch. The other factors listed are known to influence climate on shorter timescales relevant to the Pleistocene.

Question 12

Melting and evaporation are two forms of ablative calving.

Accepted Answer

Melting and evaporation are not forms of ablative calving. Ablative calving occurs when chunks of ice break off from the edge of a glacier due to friction with the rock and water below. Melting and evaporation are processes that involve the transformation of water from a solid or liquid state to a vapor state.

Question 13

Crevasses are short, narrow cracks in the plastic flow zone of a glacier that alternately open and close as the ice flows along.

Accepted Answer

Crevasses are cracks or fractures in the surface of a glacier that occur in the brittle zone near the surface, not in the plastic flow zone deeper within the glacier. They form due to the glacier's movement and the stress differences in the ice, and they do not alternately open and close but can change shape or size as the glacier moves.

Question 14

Which of the following sediment types is not glacial drift?

Accepted Answer

Pleistocene deep sea oozes are not a type of glacial drift as they are sediments deposited in deep sea environments, not directly related to glacial activity. The other options (ground moraines of till, stratified outwash fans, laminated glacial lake muds with striated and polished dropstones) are all types of glacial drift.

Question 15

The volume of the Antarctic ice sheet is about equal to the total volume of ice in all alpine glaciers of the world.

Accepted Answer

The Antarctic ice sheet holds about 90% of the world's fresh water ice, vastly exceeding the volume found in all alpine glaciers combined.

Question 16

To make glacial ice, requires a thickness of about 50 metres for pressures to be great enough.

Accepted Answer

Glacial ice forms through the process of compaction and recrystallization of snow, which requires significant pressure. A thickness of about 50 metres is necessary for the pressure to be great enough to transform snow into glacial ice.

Question 17

The great glaciation that affected the Southern Hemisphere supercontinent Pangaea (parts of Africa, South America, India, Australia, and Antarctica)occurred ________.

Accepted Answer

The great glaciation that affected the Southern Hemisphere supercontinent Pangaea occurred 300-200 million years ago in late Paleozoic time.

Question 18

All of the following are thought to possibly contribute to ice ages except for ________.

Accepted Answer

Eccentricity and precession are both known factors that contribute to ice ages by affecting the amount and distribution of solar radiation reaching Earth. Plate tectonics can contribute by altering the location and extent of continents and ocean currents. However, there is currently no scientific evidence that comets have a significant impact on ice ages.

Question 19

The downstream end or terminus of a glacier advances over intervals of time during which ablation exceeds accumulation.

Accepted Answer

The downstream end or terminus of a glacier advances over intervals of time during which accumulation exceeds ablation.

Question 20

Glaciers move so quickly that, on an annual basis, they are not very effective at removing any significant amount of water from the hydrologic cycle.

Accepted Answer

Glaciers move very slowly, often only a few centimeters or meters per day, and they store vast amounts of water for long periods, effectively removing it from the hydrologic cycle until it melts.

Quiz 17: Glaciers and Glaciation