All About Glaciers
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Background:

Glaciers form from layer upon layer of snow. Because snow is light and fluffy much of a snowflake's volume is composed of air. As new snow piles on top of old, individual snowflakes on the bottom layer are pushed together. The amount of air space between crystals decreases and a dense, closely packed form of snow results called "firn." This process takes about 1 year. As decades or even centuries pass, pressure causes the air spaces in the firn to disappear and the result is glacial ice.

Once masses of this glacial ice form, they are pulled by gravity, flowing downhill if on mountainous terrain or outward, if on flat terrain. As they flow, they carry rocks and parts of mountains with them, moving about 100 ft/yr. and picking up more rocks, sand and clay. This accumulation usually gouges the surface, changing V-shaped river valleys to U-shaped glacial valleys and carrying huge boulders and masses of gravel down the mountain to be deposited when the glacier finally melts. In the last 150 years,

Resources/Materials/Supplies:

Video Segment

Internet access

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Description:

In this activity students will:

Read about layering as a way of organizing information: Layering: http://www.graphic.org/layering.html;

Work in small groups to research, collect and organize information in an assigned category that describe glaciers and their interrelationships with the Earth's topography. Categories include:

  • Natural features of the region, such as mountain ranges, valleys, etc.
  • Definitions, typical locations and activities of different glacier types æ valley, mountain, piedmont, cirque, tidewater and hanging glaciers, etc.
  • Glacier features æ moraine, crevasse, firn, ablation area, accumulation area, etc.
  • Topographic Map of the region around the Katmai/Brooks Camp area
  • How glaciers move, grow and recede

Collate their information and layer it onto a relief map of the Katmai National Park and Preserve

  • Layer 1: Relief map of the Katmai/Brooks Camp area.
  • Layer 2: Code to label the natural features of the area.
  • Layer 3: Labels/descriptions of the kinds of glaciers found in the Katmai National Park and Preserve area.
  • Layer 4: List of glacial features coded to those features shown on the map.
  • Layer 5: Description of the ways glaciers move over Earth's surface, coded to the glaciers in Layer 3, describing how they have moved and changed over time.

Participate in a class discussion to answer the following questions:

  • By looking at the map, how can you prove that the glaciers are receding?
  • If the glaciers are receding, what does that say about the climate of Alaska?
  • Would you expect Alaska's climate to be undergoing the same changes as other glacial regions on the Earth's surface? Explain.
  • How would the map change if the Earth were to enter another Ice Age?

Management Tips and Hints:

After their reading discuss the concept of layering with them. Help them understand how they will "layer" their information on top of a relief map of the Katmai National Park and Preserve found on the Internet.

Meet with the groups in the layer order to help them construct a map or coded list to show their data.

If one group is unable to layer their data because information is missing from a previous layer, that group must consult with the group that has left out information to determine a way to resolve the problem. The first group may have to find more data or the second may find that their data cannot be shown in the Katmai layer graphic and must be left out or included as a footnote.

You may wish to share the following Hot Link with advanced students who are interested in the effects of possible global warming on the Earth.

Reconstruction of the Earth's Temperature Record for the Last 6 Centuries: http://envlib2.harvard.edu/HERO/wrapper/pageid%3Dlists%2Farchives%2Fenvconfs%2Dl%2Fmsg00730.html

Reading this information with the help of the graphic organizer at these Hot Links will help them understand its content.