Chapter 14. Glaciers and Glacial Landforms

Match the locations on the image with descriptions of glaciers present there.

A- Antarctica: it is the largest ice mass on Earth and has mostly ice sheets with some valley glaciers. B- Andes (especially Patagonia): glaciers occupy high peaks, mostly in the southern part of the mountain range. C- North America: glaciers present mainly in the higher peaks in the west. D- Greenland: large ice sheets and smaller glaciers occupy 80% of this landmass. E- Tibetan Plateau and the Himalaya: glaciers cover many of the highest parts of this area.

Match the images with their descriptions.

A: North American ice over 28,000 years ago Ice cover close to a maximum; ice up to several kilometers thick B: North American ice cover 11,000 years ago Ice age ending

Match the location on the glacier with the appropriate description

A: Snow-covered zone of accumulation Part of the glacier where snow and ice are added faster than they meld B: Part of the glacier where snow and ice are removed from the system faster than they are added Blue-ice zone of ablation

Match the features on the image with their names.

A: Esker B: Kettle lake C: Drumlins D: Recessional moraine E: Terminal moraine

Correctly identify the different types of moraines shown in the pictures.

A: Lateral moraine B: Medial moraine C: Terminal moraine

___________ is the process of scraping bedrock by an overriding glacier, and the removal of pieces of the bedrock by an overriding glacier is ______________.

Abrasion; plucking

What is glacial drift?

Any sediment transported by glaciers, icebergs, or meltwater

Match the erosional glacial landform with its description.

Arete: This is a jagged ridge formed between two glaciers. as they eroded from both sides. Tarn: This is a small lake in a glacially scoured depression. Hanging valley: The side valley is higher than the main valley; created because larger glaciers scour deeper into bedrock than smaller, side valley glaciers. U-shaped valley: Smoothing action of a glacier creates this large-scale feature. Cirque: A bowl-shaped depression is created as ice plucks pieced from the bedrock at the uppermost end of a mountain glacier.

Match the activity to the climatic effect.

Decreased sunspot activity: Climate cools slightly. Increased snow and ice cover on Earth: Increased albedo makes a cooler climate. Release of CO2 and CH4 into atmosphere: More greenhouse gases tend to warm the planet. Large volcanic eruptions: And and dust block sunlight, resulting in cooling.

Match the term on the left to its definition regarding the relative location of transport of sediment by a glacier.

Englacially: Sediment is transported within the glacier. Supraglacially: Sediment is transported on top of the glacier. Subglacially: Sediment is transported at the base of the glacier.

What processes associated with glaciers affect the landscape they exist in?

Erosion and deposition

Match the glacial features with their descriptions.

Eskers: Long, sinuous ridges deposited by meltwater stream beneath a glacier as it retreats Kettle lake: Formed as a block of ice left behind a glacier melts, leaving a depression that fills with water Glacial outwash: River-carried sediment that may either be deposited near or distant to a retreating glacier Recessional moraine: Forms as the front of a glacier melts back and stagnates for some period of time in one location, depositing a pile of sediment Till: The general name given to deposited glacial sediment Drumlins: Streamlined hills formed as a moving glacier sculpts material into this shape

Categorize the evidence by whether it represents a glacial or an interglacial period.

Glacial period: Higher ratios of oxygen-18 to oxygen-16 in the compositions of marine shells (more heavy isotopes) Higher ratios of oxygen-18 to oxygen-16 in seawater Interglacial period: Lower ratios of oxygen-18 to oxygen-16 in seawater Lower ratios of oxygen-18 to oxygen-16 in the compositions of marine shells (less heavy isotopes)

Ice sheets exist in all of the following locations except _______________.

Glacier National Park, Montana (Alpine glaciers are found in Glacier National Park for now. They are melting fast.)

What are some characteristics of glacial areas? (Select all that apply.)

Glaciers form where snow and ice accumulate faster than they melt. Glaciers flow. Glaciers may fracture, forming crevasses.

Match the type of glacier with its description.

Ice sheets: Large, regionally continuous masses of ice more than 50,000 km^2 in area Alpine Glaciers: Glaciers that begin in mountainous terrain and flow down valleys Piedmont glaciers: Broad glaciers that form when a more restricted glacier spreads out as it moves into less confined topography

Order the steps of glacier ice formation from snowflakes, beginning with the snowfall. (Place the first step at the top.)

Snow falls as individual flakes. Snowflakes are pressed together; air is forced out. Snowflakes are compressed into irregular, dense shapes. Snow changes into interlocking crystals and has a blush color.

Which of the following are true of how glaciers move? (Select all that apply.)

The coldest glaciers become locked to the bedrock at their base. The upper part of a glacier flows faster than the lower part. Rates at which glaciers move are extremely variables (a few centimeters to tens of meters per day.)

What is rock flour?

The finely ground sediment formed by glacial erosion.

Why does continental glaciation tend to smooth the surface of the land, causing the ground topography to have relatively low relief (minor height difference between lower and higher topographic locations) once the ice sheet melts? (Select all that apply.)

The ice sheets tend to deposit sediment in topographic lows. The ice sheets round and erode and of the higher areas over which the ice flows.

True or false: There were many glacial and interglacial periods over the past two million years.

True (During this time period, glaciers increased in volume many times.)

In what ways do glaciers lose mass? (Select all that apply.)

Via sublimation Via glacial meltwater Ice breaking off the glacier (Melting ice can evaporate in addition to gathering as glacial meltwater.)

When a glacier encounters a sea or lake __________________. (Choose all that apply.)

a large ice shelf may be formed if a large quantity of ice is floating on the water ice along the leading edge of the glacier may calve and form icebergs it may float on the water

A period of time in which large regions of land are covered year-round with ice and snow, especially in the last 2 million years, is __________________________.

an Ice Age

Glacial ice forms ___________________.

as snowflakes are buried and compressed, eventually becoming crystalline ice

Glaciers erode the underlying surface ________________________. (Choose all that apply.)

by glacial meltwaters through abrasion through plucking

Ice sheets are __________________ ice masses, such as those found in Antarctica and Greenland.

continental-scale

A glacier flowing over a steep drop-off or around a curve will develop cracks in its surface called _________________.

crevasses

Ancient glaciation events are indicated by the presence of ______________________. (Select all that apply.)

dropstones ridges of moraine, eskers, and drumlins tillite erratics

The area on a glacier where the accumulation of ice and snow exactly balances the loss is the ___________________.

equilibrium

A rock that has been plucked by a glacier, carried far away from its source, and eventually deposited is a glacial _______________________.

erratic

During an ice age, when most glaciers and ice sheets are advancing, the time is a(n) ______________ period, but when they are retreating, the time is a(n) ___________ period.

glacial; interglacial

A moving mass of ice, which may range in size from a huge ice sheet that covers large regions to a smaller sheet that is restricted to a single mountain or valley, is called a(n) _________________.

glacier

The rocks that glaciers transport at the base scratch the underlying surface and create striations and deeper gouge marks that we call glacial _______________________.

grooves

A _______________ feedback is one in which a change in the system causes to continue to move in that same direction. Ice, for example, decreases the surface albedo, and this tends to cool the climate even more, resulting in more ice and further cooling.

positive

By studying the processes occurring in modern glaciers and the sediment that results from those processes, we can more fully understand ancient glaciations. We are applying the concept behind the saying "the _____________ is the key to the _______________."

present; past

Glaciers can form only in places where _____________ exceeds______________, usually at higher elevations or latitudes.

snowfall; snowmelt

The lower end of a glacier, where the glacier ends either on land or in the sea is the _____________________.

terminus

This is the word we use to describe the unsorted and unstratified sediment deposited directly by ice.

till

The rock shown in this image is called tillite. It formed from glacial sediment called _____________.

tilt

Match the Milankovitch cycle change with its description.

Maximum tilt angle of the Earth: Increases the effects of the seasons; warmer summer temperatures melt more polar ice; cycles about every 40,000 years. Decreases the effect of the seasons; cooler summers lead to an increase in glaciation; cycles about every 40,000 years. Precession: Each cycle lasts about 23,000 years; this "wobble" may affect global climate. More eccentricity: Earth's orbit is slightly more elliptical; cycles last about 100,000 years. Less eccentricity: Earth's orbit is slightly more circular; cycles last about 100,000 years.

Which of the following best describes the amount of energy given off by the Sun and the composition of the atmosphere, both of which affect Earth's global climate?

Neither one is constant over time.

What land areas were largely covered by a large continuous ice sheet 28,000 years ago but are not largely covered by an ice sheet today? (Choose all that apply.)

Northern Europe Canada Northern United States Northern Asia