The terminus of a glacier is stationary when accumulation (snow) at the top of the glacier is equal to ablation (melt) at the bottom of the glacier. The snout (or terminus) of a glacier may be stationary, but the ice itself isn’t. Glaciers that are neither advancing nor receding are stationary The following selected text is taken from : Common misconceptions about glaciers. Read the NSTA review of this lesson for ideas on how to adapt it for fuller NGSS alignment. Teachers: This is a NSTA-vetted resource. Until recently, glaciologists had no accurate means of seeing the aerial extent of glacier ice on Earth. Furthermore, ice sheets and ice caps are so huge and change so slowly that repeated measurements are needed over large areas and long periods of time. However, direct observations of glaciers are often difficult because they exist in cold, polar regions or high mountain areas that are inaccessible or inhospitable to humans. Glacier-monitoring efforts in national parks provide valuable information to park managers, as well as to the scientific community at large, about the effects of regional and global climate change. In fact, most of Alaska’s estimated 10,600 glaciers are melting. Monitoring the glaciers can help determine why they are retreating. Glaciers are retreating not only along Kenai Fjord’s coast but all throughout the park. As a result, Bear Glacier, once classified as a tidewater glacier, is now a terrestrial glacier. In fact, the beach in front of Bear Glacier is an old recessional moraine that has cut off Bear Glacier’s access to the tidewater’s edge. Bear Glacier, as it retreated, paused long enough to build up a sizeable moraine. As the glaciers retreat, these coastal valleys are filled with seawater, creating fjords. Changes in precipitation have caused Bear Glacier to recede. As glaciers recede, they leave behind rock and debris, which is called a moraine. Write them down and then use them to calculate the class average.Īlong the coastline of the park, glaciers have cut deep valleys into the mounta ins. Your teacher will ask for everyone’s results and then list them on the board.Once you have determined how many grid squares represent a change in glacier cover, you will use this information to calculate the percent cover change in the satellite images provided of Bear Glacier. Repeat Steps 3-6 using the 2018 Landsat 8 image.Work from the upper left to the upper right across each row, putting a dot in each square that represents a change in glacier cover. The other partner will mark the equivalent changed squares using the Cover Change Grid.In this case, the most dominant cover type should be used. You may notice that some squares contain land that is only partially covered by the glacier. One partner will compare the transparency map to the 2002 satellite image and identify the grid squares that show glacier change.Count and record the number of grid squares representing a change in glacier cover.Using a different color of marker than you used in Step 3, trace the outline of the 2002 glacier on the transparency grid.Place the transparent glacier cover map you just made over the 2002 image of Bear Glacier and tape the corners to hold it in place.Make a legend for your transparency cover change grid, which is now becoming a glacier cover map.One partner will hold the image while the other partner outlines the glacier cover on to the transparency with a colored marker.Place the transparency with the cover change grid over the image from 1986, and tape the corners of the transparency to the image.Be careful not to include the icebergs floating in the lake or snow that has collected in the mountains that is not part of the glacier itself.Together with your partner, visually identify the areas in each image that are covered by Bear Glacier.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |