Glaciers 5 points
(missing 3 questions = -1 pt)
Name________________
A glacier gains mass in the zone of accumulation and loses mass in the zone of ablation. In an alpine
glacier, the zone of accumulation occurs at higher elevations. As the glacier moves, tensional cracks known as
crevasses often form in the ice as the glacier passes over steeper terrain. During the summer melting season, the
zone of accumulation will still have fresh snow cover. The zone of ablation is at lower elevations. During the
summer melting season, the ice will show glacial till in and on its surface in the form of moraines. This will
look like dirty ice. These two areas are separated by the equilibrium line (the snow line). The net balance of a
glacier tells us whether it is advancing or retreating.
Section One: Mass balance of a glacier
http://ak.water.usgs.gov/glaciology/south_cascade/index.html
South Cascade Glacier, Washington, is one of three glaciers in a long-term monitoring project to determine the
connection between glaciers, climate, and runoff. See the photo comparisons between 1928 and 2010.
1. Has the equilibrium line between the zone of accumulation and the zone of ablation moved up or down?
2. Based on visual interpretation of the photos, is the glacier gaining or losing mass?
Is the glacier in a stage of advance or retreat?
3. Select the Mass Balance for this glacier from the menu on the left and download the time-series data table.
The right column is the net balance. Based on this data, is the glacier gaining or losing mass?
4. Launch Google Earth and enter South Cascade Glacier, WA in the search box. The little green triangle is
Sentinel Peak, a horn.
What are the ridges leading down and away from it?
5. Search for South Cascade Lake. Use the Ruler Tool and draw a line from the arête to the north of the lake,
passing next to the S in South Cascade Lake, and on to the arête to the south of the lake. Save as Valley and
make sure the altitude is clamped to the ground in the Save dialog box. Click OK. Find Edit menu and Show
Elevation Profile.
Is the elevation profile a V or a U shape?
What does this tell you about the extent of the glacier in the past?
What is exiting the west side of the lake?
Where would you find glacial outwash? Move your cursor to that spot and recorde the latitude/longitude
coordinates.
Section 2: Alpine glaciers and their landforms
Alpine glaciers produce erosional landforms that are very rugged, often on or near steep slopes.
Examples include a U-shaped valley known as a glacial trough, hanging valley, horn, arête, tarn, and
paternoster lakes. These erosional remnants were plucked and abraded by the alpine glacier as it moved down
the valley. Eventually, the rock debris is deposited by the ice as glacial till in the form of moraines. The rock
debris may also be reworked by glacial meltwater and deposited as sorted and layered glacial outwash.
http://3dparks.wr.usgs.gov/ Need the cardboard stereoglasses. Select Mt Ranier.
On the map, select Carbon Glacier to view a series of photos.
Pinnacle Peak – what is the sharp ridge leading down from the peak?
Nisqually Creek – what shape does this valley have?
Terminus of Carbon Glacier – How can you tell the difference between the glacial till and the glacial outwash in
this image?
Plate 47 in stereophoto book, Crillon Glacier, Alaska
1. How many kilometers wide is the Crillon Glacier?
Chief Mountain, Montana individual topo map
1. What is the glacial term for Mt. Grinnell in the center of the map?
2. What is the glacial term for the ridge extending from the mountain down toward Grinnell Point?
3. What is the glacial term for Iceberg Lake?
4. What is the glacial term for the valley occupied by Lake Sherburne near the eastern edge of the map?
5. Some glaciers still exist. They are found on slopes that face mostly _____________.
6. Why aren’t there glaciers found at the same elevation on slopes that face south or southwest?
Mt Rainier, Washington individual topo map. Glacier contours are in blue in the zone of accumulation and
covered by brown dots in the zone of ablation.
1. If the glaciers were rivers, what would the drainage pattern be?
2. What is the length in miles of Winthrop Glacier from the summit of Mt. Rainier to its terminus?
3. What is the evidence that glaciers have extended farther down the valley in the past than they are today?
Plate 7 in the stereophoto book, Wyoming
1. Although alpine glaciers are no longer present, what is the evidence that they sculpted this landscape?
Section 3: Continental glaciers and their landforms
Continental ice sheets move outward in all directions from the central zone of accumulation. These
erosional features, such as glacial grooves and roche moutonnee, and depositional features formed from either
glacial till or glacial outwash tend to have less topographic relief than features in alpine regions. Lateral and
medial moraines are generally not found in areas of continental glaciation since they form in association with
the edges of mountain valleys. Common landforms include many types of moraines, kettle lakes, drumlins,
kames, eskers, and large outwash plains.
Page 63 in topo map book, Paterson, New Jersey
1. The hills labeled with elevation at 740 and 862 ft are drumlins. Based on the contour lines, which side of the
drumlin, north or south, is the steepest?
2. What does that imply about the direction of ice flow?
3. What are drumlins made of?
Page 52 in topo map book, Jackson, Michigan
1. What is the glacial term for these lakes?
2. What kind of drainage pattern is represented?
3. What does this imply about the age of the landscape?
4. How did these lakes form?
Whitewater, WI individual topo map
1. Name and describe the type of glacial depositional material that you would find in the Kettle Moraine State
Forest.
2. Why is the Kettle Moraine State Forest so much higher in elevation than the area to the northwest or
southeast?
4. In the Whitewater area, from what direction did the continental ice sheet advance?
Passadumkeag, Maine individual topo map.
1. As you follow the Penobscot River downstream, what happens to its elevation?
2. Find Hoytville Horseback on the topo map. This esker is composed of sand and gravel. As you travel on the
crest of the esker, what happens to its elevation?
3. Why can’t we call the esker a river channel deposit?