Glaciers

Glaciers cover how much of the land surface of the Earth?

10%

Glaciers store how much of the worlds freshwater supply?

75%

Can you name two continents that have continental glaciers?

Antarctica and Greenland

Glacial and inter-glacial periods are likely caused by the variations in the Earth's position and orientation relative to the Sun. This hypothesis is called the ____________ __________.

Milankovitch hypothesis

The ice age occured 1.6 (or 1.8) million to 10,000 years ago during the ___________ _______.

Pleistocene epoch

The amount of water and ice a glacier looses is greater than the amount of snow it gains, then it will ___________.

Retreat

Plastic flow occurs in...

The lower part of the glacier between the interface with the bedrock and the overlying zone of rigidity.

How would you define till?

Till is poorly sorted and unlayered debris composed of gravel, sand and clay deposited by a glacier.

A valley that once was occupied by a glacier is typically described as ____________.

U-shaped

Lower part of the glacier where calving, melting, and evaporation occur...

Zone of wastage

Relative to the zone of plastic flow where does the rigid zone occur?

above the zone of plastic flow

Glaciers that are confined to valleys are called ___________ or ___________ glaciers.

alpine, valley

If all the global supply of the land ice stored in glaciers melted, then how far would sea level rise?

approximately 7 meters

In the following illustration what is the knife-sharp ridge separating adjacent glacial valleys called?

arete

What are the ampitheatre-like depressions occuring at the heads of the glacial valleys in the following illustration called?

cirques

The terminus marks the farthest ________ extent of a glacier.

down valley

In the following illustration what are the streamlined hills of sediment called?

drumlin

The following illustration schematically depicts the orbital path of the Earth around the Sun as varying from nearly circular to highly elliptical. It takes the Earth ~100,000 years to complete this cycle. What is the term used to describe this cyclical variation in the shape of the Earth's orbit?

eccentricity

In the following illustration what is the name of the ridge of till that lies along the terminus of the valley glacier?

end moraine

In the following illustration what is the long sinuous ridge composed of water-deposited sediment called?

esker

In the following photograph what do you call the blocks of granite resting on the polished glacial surface at Ohmsted Point, Yosemite National Park? Note that they are totally unlike the plutonic rock that they rest on.

exotic blocks

The grooves in the bedrock illustrated in the photograph below are produced by the grinding of rocks caught up in the flowing glacier against the solid bedrock. What are the grooves in the polished glacial surfaces called?

glacial striations

In the illustration, you can still recognize some aspects of an ice crystal, but how much of the elegant crystal outlines have been destroyed. What is the name of the feature shown in the illustration?

granule

A glacier moves under the influence of it's own weight and __________.

gravity

The feature illustrated below is an example of a valley once occupied by a tributary glacier. Bridalveil Creek in Yosemite National Park is another example. What do you call such valleys?

hanging valleys

In the following illustration Mt. Russell and Mt. Carillon are pyramid-like in form. They were produced by the head ward erosion of glaciers that once occupied the valleys that now surround them. What are Mt. Russell and Mt. Carillon?

horns

Snowflakes are ______ crystals.

ice

Glaciers that are not confined to valleys and cover less than 50,000 square kilometers are called

ice caps

Glaciers that cover more than 50,000 squared kilometers are called

ice sheets

If sediment is washed into opening and depressions at the terminus of a wasting continental glacier, then a small hill is left behind. What is this small hill called?

kames

When blocks of ice buried by sediment along the retreating margin of a continental glacier melt a depression forms. In the following illustration what are these lake-filled depressions called?

kettles or kettle lakes

In the following illustration, two valley glaciers merge to form one. What are the ridge-like accumulations of till located along the margins of each valley glacier called?

lateral moraine

When two valley glaciers merge till accumulating along their interiors also merge to form a single distinctive ridge lying between the two glaciers. What is this distinctive single ridge composed of till called?

medial moraine

Glacial plucking is produced by the movement of the glacier away from the areas where _______ ________ has seeped into cracks and frozen.

melt water

As shown in the following illustration the Earth's axis wobbles like a top slowing down as it orbits the Sun. The Earth completes one cycle of this wobble every 20,000 years. What is the term used to describe this cyclical variation?

obliquity

The following illustration schematically depicts the tilt of the Earth's axis either toward or away from the sun as varying over the range of 22.5 degrees to 24.5 degrees. Currently, the tilt is 23.5 degrees. It takes the Earth about ~43,000 years to complete one cycle of this variation in tilt. What is the term used to describe this cyclical variation?

obliquity

In the following illustration, what is the series of glacial lakes called that occupy a valley once occupied by a glacier?

paternoster lakes

What would you call the ridge of material shown in the illustration for question 39 if it was produced by a glacier that was retreating?

recessional moraine

A crevasse in an open void or crack that occurs in the zone of ___________.

rigidity

In the following illustration, what is the smoothed streamlined hill cut into the bedrock called? Note that the glacier flowed from right to left.

rouche mountonnée

A continental glacier is distinguished from an alpine or valley glacier by

size-they exceed 50,000 squared kilometers location-they are not confined to valleys

A snowpack is defined as the result of multiple _________ over a _________ _________.

snowfalls, single winter

A line marking the highest point at which a glacier winter snow cover is lost during a given season is called the

snowline

The grooves in the bedrock illustrated in the photograph below are produced by the grinding of rocks caught up in the flowing glacier against the solid bedrock. What are the groves in the polished glacial surface called?

snowline

What are glacial lakes called?

tarns

What would you call the ridge of material shown in the illustration for question 39 if it was produced by a glacier that had reached its most down valley extent?

terminal moraine

In the illustration below, three small valley glaciers feed the main valley glacier. What are these smaller glaciers called?

tributary glacier

In the following photograph and illustration the ridges extending down into the main glacial valley have been truncated by the large glacier once occupying the valley. What are these truncated ridges called?

truncated spurs

In the following illustration, the main valley glacier is fed by three smaller glaciers. What do you call the main valley glacier?

trunk glaciers

Powder is composed of ice crystals and _____ filled with air.

voids

Basal sliding refers to the movement of the _________ __________ over bedrock.

whole glacier

Upper part of the glacier that is covered with snow year round...

zone of accumulation