ES 1 Chapter 7: Glaciers, Deserts, and Wind

Comprehensive practice flashcards reviewing glacial features, desert landscapes, and wind erosional/depositional processes from Chapter 7 of Fundamentals of Earth Science.

What is a glacier?

A thick mass of ice that forms above the snowline over hundreds or thousands of years.

What is an Ice Age?

A period when much of Earth's surface was covered in glaciers.

How is a valley glacier defined?

An ice mass that slowly advances down a mountain valley once occupied by a stream, flowing between steep rock walls.

What is an ice sheet, and where are present-day ice sheets located?

An enormous ice mass flowing in all directions from one or more centers, covering everything but the highest land; currently found in Greenland and Antarctica.

What are the two ways glacial flow occurs?

Plastic flow (movement within the ice) and basal slip (ice slipping/sliding downward due to gravity).

What is the glacial budget?

The balance or imbalance between accumulation (gain of snow/ice at the upper end) and wastage (loss of ice at the lower end).

What is the difference between the zone of accumulation and the zone of wastage?

The zone of accumulation is the upper area above the snowline where snow builds up, while the zone of wastage is the lower area where ice is lost.

What are crevasses and calving?

Crevasses are cracks in the ice, and calving is the breaking off of ice at the glacier's edge to form icebergs.

How do plucking and abrasion differ as mechanisms of glacial erosion?

Plucking occurs when a glacier lifts and carries away blocks of rock, while abrasion occurs when embedded rock debris grinds and scrapes bedrock, producing rock flour and striations.

What erosional landforms are produced by glaciers?

Glacial troughs (U-shaped valleys), hanging valleys (tributary valleys left hanging above the main trough), cirques (bowl-shaped depressions), arêtes (sharp, jagged ridges), and horns (pyramid-like peaks).

What is the difference between till and stratified drift?

Till is material deposited directly by the glacier and is unsorted, whereas stratified drift is sediment deposited by glacial meltwater and is sorted and layered.

What are the key depositional landforms formed by glaciers?

Moraines (ridges/layers of till), outwash plains (sloping sediment plains from meltwater), kettles (depressions from buried, melted ice), drumlins (streamlined asymmetrical hills of till), and eskers (ridges of sand and gravel from subglacial streams).

When did the Ice Age begin, which epoch does it correspond to, and how much land did ice cover?

It began $2\text{--}3\text{ million years}$ ago during the Pleistocene epoch and covered about $30\,\%$ of Earth's land area.

What are ephemeral streams and why do they dry up in deserts?

Desert streams that carry water only after rainfall; they typically dry up before reaching the ocean due to evaporation and infiltration.

Which agent does most of the erosional work in deserts?

Running water.

What are playa lakes and alluvial fans?

A playa lake is the flat floor of an undrained desert basin (playa) that temporarily fills with water after heavy rain; an alluvial fan is a fan-shaped sediment deposit formed where a stream's slope abruptly decreases at a mountain base.

What is deflation in wind erosion and what features does it create?

Deflation is the lifting and removal of loose, fine particles (clay, silt); it produces blowouts (shallow depressions) and desert pavement (a layer of coarse pebbles and gravel).

What is loess and what are its primary sources?

Blanket-like deposits of windblown silt; its main sources are deserts and glacial stratified drift.

What are the slip face and cross beds of a sand dune?

The slip face is the steep, leeward (downwind) slope of a dune, and cross beds are the sloping, layered internal structure formed as the dune migrates.

How do barchan, transverse, and barchanoid dunes differ?

Barchan dunes are crescent-shaped with horns pointing downwind (limited sand supply); transverse dunes are wavy ridges perpendicular to the wind (abundant sand, little vegetation); barchanoid dunes are wavy rows of connected barchans.

How are longitudinal, parabolic, and star dunes defined?

Longitudinal dunes are long ridges parallel to wind direction; parabolic dunes are U-shaped with horns pointing upwind (anchored by vegetation); star dunes are pyramid-shaped with radiating ridges formed where wind blows from multiple directions.