Glaciers and Glaciation
Which is the only continent that does not presently have glaciers?
Australia
Medial moraines demarcate the various tributaries of a glacier and form when two end moraines merge.
False
Sea level has fallen dramatically since the Pleistocene Epoch.
False
There is good evidence that variation in solar energy, as evinced by sunspot activity cycles, is responsible for short-term climatic variations.
False
What happens to ice movement within a glacier when the glacier is retreating?
The ice flows downhill.
Which statement about valley glaciers is true?
They tend to flow faster than continental glaciers.
According to the Milankovitch theory, variations in Earth's orbit and axial tilt can trigger long-term climatic changes and prompt the start and end of ice ages.
True
Basal slip becomes a more important means of glacier movement in warmer months when more meltwater collects at a glacier's base.
True
Continental glaciers generally flow on the order of centimeters to meters per day.
True
End moraines continue to grow as long as the ice front remains stationary.
True
Glacial striations, roche moutonées, and drumlins allow scientists to identify the direction of glacial movement.
True
Glaciers are geologically important because they erode, transport, and deposit so much material.
True
The majority of glaciers on Earth are melting in response to warmer temperatures.
True
A glaciers budget is balanced when ____.
additions to the zone of accumulation equal losses in the zone of wastage
Ice Ages ____.
are the result of variations in the amount of solar heat received
A glacial landform that forms at the head of glacial valleys or troughs is called a(n) ____.
cirque
Which of the following is an erosional feature of glaciers?
cirques
Which of the following is a depositional feature of glaciers?
end moraine
Which type of glacial deposit was formed by running water?
eskers
A terminal moraine marks the ____.
farthermost point of a glacier's advance
What term describes the straight scratches on rock surfaces created by glacial abrasion?
glacial striations
Orbital eccentricity refers to ____.
how circular or elliptical Earth's orbit is
In the process of sublimation, ____.
ice changes directly into water vapor
In a cross-section of a glacier, where do the greatest flow velocities occur?
in the few tens of meters below the surface
Suppose that glacial ice were a rock. What type of rock would it be?
metamorphic only
The most important process by which glaciers move is ____.
plastic flow
If wastage is greater than accumulation, a glacier is said to be ____.
retreating
Worldwide, the majority of glaciers are ____.
retreating
A glacial landform produced primarily by plucking rocks on the downstream side and smoothing by the glacier on the upstream side is called a(n) ____.
roche moutonée
A glacier forms when ____.
snow accumulates to form ice, and the ice mass begins to flow under its own weight
The three stages involved in the formation of glacial ice are, in order, ____, ____, and ____.
snowfall; firn; glacial ice
What is a lake formed within a cirque?
tarn
The health of a glacier and the glacial budget are determined primarily by ____.
the amount of snowfall and temperature
Mountain valleys subjected to glaciation are typically shaped like ____.
the letter "U"
Glacial till is ____.
unstratified sediment deposited directly by a glacier
A glacier that is unconfined by topography and has tributaries is a(n) ____.
valley glacier
Short-term climatic changes like the Little Ice Age are poorly understood. One hypothesis for why short-term climatic events occur is ____.
variations in solar radiation
How much of Earth's surface is covered by glaciers?
10%
When did the Pleistocene Ice Age end?
11,700 years ago
A glacier begins to flow when the ice reaches what critical thickness?
40 M
