Glaciers

EES 101

What is a glacier?

It is essentially rivers and lakes of ice. They are large masses of moving ice which comes from snow.

Where and how do glaciers and glacial ice form?

They form at the polar regions and at high elevations when the winter’s snowfall is greater than the summer’s melt.

What portion of the Earth’s land area is covered by glaciers?

10%

What percentage of total water is held in glaciers?

2%

What are Alpine glaciers?

They occur in mountainous areas. Their length is greater than their width. They create U-shaped valleys and are also called valley glaciers.

What are continental glaciers?

They are large scale glaciers found in polar regions. They are also called ice sheets. Examples include Greenland which is 1.7 million km² and Antarctica which is 13.9km².

Explain the glacier budget.

The accumulation zone is the area where the glacier grows with snow. The zone of ablation is the area where the glacier melts or decreases. The snow line is the area where accumulation and wastage are equal.

What is the primary force behind glacial movement?

Gravity and slope

What is plastic flow?

It is movement within the ice.

What is basal slip?

It is when the entire ice mass slips along the ground, slowed by friction.

Where does the glacier move the fastest?

In the top center.

What is abrasion?

Sediments in ice that act as giant sandpaper (striation).

What is plucking?

When blocks of rock are loosened and lifted by ice flow.

What are the most obvious eroded features caused by Alpine glaciation?

Sharp angles

What is a horn?

It is a sharp peak carved by a glacier

What is an Arete?

It is a sharp ridge carved by a glacier.

What is a cirque?

It is a circular crest where glaciers originate.

What is a tarn?

They are lakes formed when glaciers melt in cirques.

What are U-Shaped valleys?

They are valleys caused by Alpine glaciers.

What are hanging valleys?

They are the tributaries to glacier valleys.

What are Fjords?

They are U-shaped valleys drowned by rising sea levels. They are narrow inlets of the sea between cliffs and steep slopes which results from marine inundation of a glaciated valley.

How do ice sheets erode the landscape?

They create rounded features and flat plains, like the Canadian shield.

What is a kettle?

It is when an ice block creates a depression, and when the ice melts, it fills the depression.

What is till?

It is the unsorted debris left by glaciers. It can be as small as a grain of clay or as large as a boulder. It can create rocks known as Tillite.

What is a Moraine?

It is a deposit of till at or near margins of glaciers.

What is a terminal/end moraine?

It is a moraine at the outermost limit of a glacier’s advance.

What is a medial moraine?

They are moraines that form when two tributary glaciers join.

What is a lateral moraine?

They are parallel ridges of debris along the sides of a glacier.

What is an erratic?

It is a glacier deposit of very large boulders transported by glaciers and dropped.

Did glaciers ever reach Kentucky?

No

What is a drumlin?

They are bodies of till shaped into streamlined hills. The narrow end points in the direction of ice flow.

What is Loess?

It is wind-blown silt that is derived from outwash plains. It forms Kentucky’s soils.

What is the Ice age?

It is a period of time when glaciers cover a large part of the Earth’s surface.

What does the Milankovitch hypothesis say causes glaciations?

The shape of Earth’s orbit, the angle of Earth’s axis, and the axis’s wobble. Other reasons could be changes in the atmosphere and variation sin the sun’s energy.

How cold was it during the Great Ice Age?

Only 5 degrees colder on average.