Alaska Satellite Facility
Delivering Remote Sensing Data Since 1991

Segment Review Questions
Teacher's Guide

What's 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 & 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, & 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

 
    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
    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's a Crevasse" segment
   

Brain Challenge!
    Do you think a surging glacier could knock down Mt. McKinley?

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?

Calving

    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!)

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