MG CH 15 – Flashcards
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Which of the following responses best defines the movement of ice within a glacier?
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Glacial movement is always in a downslope direction
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The terminus of a glacier will advance when which of the following conditions is met?
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Accumulation of snow is greater than wastage
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Which of the following best describes the position and/or migration of the snowline on an active glacier?
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The snowline moves downslope when the glacier is advancing
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Working in a mountain valley that contains an alpine glacier, you discover a series of end moraines in the valley. As you move up toward the glacier, what conclusions can you expect to make about the moraines?
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The moraines get younger as you get closer to the glacier
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During the Cold War, a B-52 bomber accidentally dropped an unarmed nuclear device on the Greenland Ice Sheet. Upon returning to the drop zone many years later, the device had gone missing. As a glaciologist on the project, where should you look for the missing device?
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To find it you should go downslope from the drop zone, in the direction of ice flow
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Where do glaciers form?
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In places where more snow falls in the winter than melts away in the summer
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What is the snowline?
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The elevation above which snow persists throughout the yar
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What is the zone of wastage?
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The part of a glacier where snow melting exceeds snow accumulation
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Under what conditions will the front of a glacier remain stationary?
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Glacial fronts remain stationary when melting and snow accumulation are equal
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What is an end moraine?
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A ridge of debris deposited at the end of a glacier
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How does an end moraine form?
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Pieces of rock are transported to the front of a glacier as ice within the glacier moves
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Will plucking occur if a glacier is NOT advancing?
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Yes, because glacial ice is still moving inside the glacier even if the glacier's front is not advancing
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A ___ is defined as a chain of glacial lakes where each lake flows into the next.
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Pater noster lake
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What is the best way to describe the shape of a glacial valley?
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U-Shaped
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What is the name for an isolated boulder of unexpected rock type that has been transported by a glacier and stranded after the ice melts?
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erratic
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What causes a crevasse to form?
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When ice flows around a bend or over an obstacle, it is stretched and torn, causing large cracks to form
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What causes streams that emerge from glaciers to be milk-colored?
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The presence of finely ground sediment called rock flour in the meltwater
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What shape is a glacial trough?
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U-Shaped
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Most modern glaciers are ___.
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Retreating
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Which two regions currently contain the world's last remaining ice sheets?
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Antartica and Greenland
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When was the last time North America had major ice sheets?
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18,000 years ago
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Which landform marks the furthest extent of an advancing glacier?
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terminal moraine
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What feature is responsible for creating eskers?
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streams that flowed below, in, or on the glacier
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Which orbital effect describes how the shape of Earth's orbit around the Sun will change over time?
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eccentricity
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What is the critical latitude for incoming solar radiation, which could affect the formation of ice sheets?
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65 degrees N
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How many years does one complete cycle of precession take?
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26,000 years
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What effect will an increased angle of tilt have on the Earth's climate?
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warmer summers and colder winters
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Which of the following scenarios will have the greatest chance of triggering an ice age?
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eccentricity, obliquity, and precession overlapping to provide the least amount of solar radiation
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A(n)___ would logically be situated next to a large end moraine or terminal moraine.
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outwash plain
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What type of moraine is formed by the merging of two lateral moraines at a junction of two valley glaciers?
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medial
