Alaska Satellite Facility - Distributed Active Archive Center

Glacier Power – Teacher Answer Key Segment Review

Segment Review Questions Teacher's Guide

What is a Glacier?

How does the glacier move down it’s slope? Gravity

Are all glaciers the same? No

Where are the world’s largest ice sheets found? Antarctica and Greenland

Do ice shelves float? Yes

Which are bigger, ice shelves or ice caps? Ice Shelves

From what sources might you see a valley glacier flowing? Cirques, ice caps, highland ice fields, or ice sheets

What does SAR stand for? Synthetic Aperture Radar

In what season is meltwater abundant, summer or winter? Summer

Do cold glaciers erode a lot? No 

Brain Challenge!
When rivers freeze, do they turn into glaciers?

Where Have Glaciers Been?

What three continents were covered in ice sheets for 2 million years? North America, Europe, and Asia

What made the glaciers melt two million years ago? Rising Temperatures

Why do geologists and glaciologists study the Ice Age? To find out what happened in the past and what may happen in the future

Do glaciers leave clues behind? Yes or No? Yes  

Name two clues that glaciers leave. Scraped rock, huge boulders, u-shaped valleys, silt, fjords

What two things have to be just right for a glacier to exist? Temperature and precipitation

What does “deposition” mean? The laying down of matter by a natural process

What does “erosion” mean? Process by which material is worn away from the Earth’s surface

What is the difference between a U-shaped valley and a V-shaped valley? U-shaped valleys are formed by glaciers and V-shaped valleys are formed by rivers   

Brain Challenge!
Have glaciers been around where you live? How can you tell?

Anatomy and Other Diagrams of a Glacier

Is the accumulation zone near the upper or lower region of a glacier? Upper

Is the ablation zone near the upper or lower region of a glacier? Lower

The process of calving stops, balances, or increases (pick one) the flow of ice from behind? Balances

True or False: Meltwater flows along the top of glaciers. False

Explain what process is occurring in #3 on the glacier anatomy image. What does it tell you? The equilibrium line divides the accumulation zone and the ablation zone. 

What is the fastest a glacier can surge? 5 times faster than it normally goes or 100 times faster than it normally goes? 100 times faster than it normally goes

In a surge, can a glacier swallow its own valley? Yes

In the diagram in this section that shows what happens when a glacier surges, look at letter B and find out what it’s about. The glacier surging, sliding downhill.

Draw a diagram of shearing at the side of a glacier. (Hint: it’s in the diagram of “types of crevasses”) Located also in the “What is a Crevasse” segment   

Brain Challenge!
Do you think a surging glacier could knock down Denali? 

Strange Glacier Phenomena

Can glaciers make sounds? Yes. such as ice sizzles, ice quakes (a traveling/cracking sound), and the roar of moulins

What are small black wingless springtail bugs that live in firn on glaciers? Glacier fleas

What do ice worms eat? Algae and pollen

There is an image of a fossil in glacial till in this section. What is the fossil? A log or a stump

What are sudden glacial outburst floods of water that can be catastrophic? Jokulhlaups

Do ice quakes sound like earthquakes (rumbling sound) or do they make a hissing and crackling sound? Hissing and crackling sound

Are moulins holes in a glacier or the steel spikes you put on your boots to hike on a glacier? Holes in a glacier   

Brain Challenge!
Would you ever want to be an ice worm? Why or why not?

What are Crevasses?

What can cause a crevasse? Stress in the ice, by ice flowing over bumps or steps in the bedrock

Why don’t crevasses reach to the very bottom of the glacier? Most are squeezed shut by the pressure of the ice below about 30 meters (100 feet)

Where is the most common place on a glacier to find longitudinal or splay crevasses? Near the terminus

What causes marginal crevasses? Shear between the valley wall and the glacier

In a deep crevasse, can scientists see the ice crystals of a glacier? Yes or No? Yes

Why do scientists go down into crevasses: to observe the layers of snow or to test their bravery? To observe the layers of snow

Transverse crevasses form across a glacier where the speed is (pick one) increasing or decreasing? Increasing

Radial crevasses form where a glacier turns a corner. True or False. True

In which zone of a glacier are transverse crevasses most common? Accumulation zone   

Brain Challenge!
What would you do if you ever fell into a crevasse while climbing on a glacier?

Danger and Safety

What is a tower of ice surrounded on all sides by crevasses? A serac

What causes a block of ice to break off and fall? Stress

What do snow bridges cover on a glacier? Crevasses

Does wind drifting cause mechanical hardening in the snow? Yes

Should you walk over a snow bridge? No

What do glacier travelers wear on their boots so they don’t slide on the ice? Steel spikes called crampons

Name two correct ways to travel on a glacier. Travel in a team, use ropes to tie team members together for safety, have an experienced glacier climber with you, and use proper equipment.

Name a piece of proper clothing to wear when traveling on glaciers. Boots, warm jacket, warm pants, and gloves

If they go fast enough, snow machines can cross a snowbridge safely. True or False? False   

Brain Challenge!
What one thing you would like to do on a glacier?

How do Glaciers Form?

The formation of a huge glacier begins with a single, small _____________? Snowflake

What types of summer temperatures need to occur for a glacier to form? Cooler temperatures so snow stays on the mountain

How does over-lying weight affect the snow? It makes snow grains beneath become coarser and larger

What is wetted snow that has survived one summer without being transformed to ice? Firn

How long does it take for firn to form? About one year

When does firn become glacial ice? When the interconnecting air passages between the grains are sealed off

What is the line that separates bare ice from snow at the end of the ablation season? The firn line

What is the difference between a perennial snow patch and a glacier? A glacier flows

What causes a glacier to move downhill? Gravity   

Brain Challenge!
What would Alaska look like if all of the glaciers melted?

How do Glaciers Move?

What causes the glacier to be in motion? Gravity

True or False: Glaciers slide on their beds and this enables them to move faster. True

True or False: Glaciers can’t flow down to sea level or carve fjords. False

What is the zone where a glacier gains snow and ice? The accumulation zone

What is the zone where a glacier loses ice through melting and calving? The ablation zone

What is the difference between the amount of material that a glacier accumulates and the amount it loses during ablation? Mass balance

If the glacier gains more than it loses, will the glacier have a positive or negative mass balance? A positive mass balance

True or False: The snout is another name for the terminus on a glacier. True

Name one type of moraine. Terminal, lateral, or medial   

Brain Challenge!
When climbing a glacier, if you could only bring one other thing with you besides warm clothes, boots, and a camera, what would you bring?


Do glaciers have cows? No

What are chunks of ice that break off of glaciers and fall into the water? Icebergs

List the three rules starting with the letter “L” that you should do at Child’s Glacier. Look, Listen and Leave

Do you move to higher or lower ground when you see a glacier calving? Higher ground

One of the rules is to “Look” at Child’s Glacier. What can you probably see in the woods? Large rocks

There are photographs taken of Child’s Glacier calving. How high did the wave reach? 12 feet

What town in Alaska is Child’s Glacier close to? Cordova

If an iceberg has lots of bubbles inside, what color might it be? White

What does a darkly-striped iceberg consist of? Frozen water and moraine debris   

Brain Challenge!
What would it be like if you were in a boat and a glacier started to calve? Do you think it would rock your boat if you were right next to the glacier?

Why is Glacier Ice Blue?

Glacier ice is so blue because the dense ice of a glacier absorbs/reflects (circle one) every other color of the spectrum except blue/yellow (circle one). Absorbs and blue

Glacial ice is different than regular ice. True or False? True

Are there rocks in glacial ice? Why or Why not? Yes, because glaciers move through rock and soil as they carve their way down slope

What could happen to your glass of water if you dumped glacial ice in it? Your glass could explode!

What is the stuff called that is either alive now or was alive in the past (it may be trapped in glacier ice)? Organic matter

True or False? Glacial ice is just like the water in your freezer. False

What would be in your glass of water if the glacial ice melted? dirt, gravel, and organic matter (living stuff)

Glaciers are just frozen compacted snow. True or False? False

The ice on a glacier has been there for a long time and has been compacted down. True or False? True   

Brain Challenge!
If all the glaciers in the world melted, what would happen? (Use your imagination!)

Why do Scientists Study Glaciers?

Name one thing you can find out by studying glaciers. How the atmosphere was a long time ago

As the ice compacts, is there more/less pore space? Less pore space

Glaciers sometimes make popping sounds. Why? Pressurized air escapes from the ice

What is another big word for “warm spells”? Interglacials

How long was each interglacial period? 10,000 years

18,000 years ago, there was an ice age. How much (%) of the world’s land surface was covered under thick ice? 30%

Dr. Craig Lingle likes to study glaciers. What kind of scientist is he? A glaciologist

What is the largest glacier in North America? Bering Glacier

What did James Roush and Dr. Craig Lingle use to look at glaciers from space? SAR or Synthetic Aperture Radar satellite imagery

Brain Challenge!
Do you think there will be an Ice Age or Global Warming in the next 100 years? (Don’t worry, there is no wrong answer!)