exercise 21 - Glacial landforms

Glacial Mass Balance

1. a. See table.

b. See table.

Table 1. Glacial Mass Balance Data. Units in inches water equivalent.

Elevation Glacier 1 Glacier 2 Glacier 3

(feet) B_s B_w B_n B_s B_w B_n B_s B_w B_n

10,000 -13 +20 7 -14 +19 5 -19 +20 1

8,000 -23 +27 4 -24 +24 0 -13 +19 6

6,000 -26 +15 -11 -30 +18 -12 -10 +20 10

4,000 nr^* nr nr nr -10 +10 0

2,000 nr nr nr nr -12 + 4 -8

0 nr nr nr nr nr nr

Total -62 62 0 -68 61 -7 -64 73 9

* nr: no record

2. a.

b. At high altitudes, net mass balance is positive. As altitude decreases, net mass balance decreases and becomes negative at lower altitudes.

3. a 0 (zero)

b. Glacier 1: 7500 feet

Glacier 2: 8000 feet

Glacier 3: 4000 feet

c. Glacier 3

d. Glacier 3 is located at a higher latitude than Glaciers 1 and 2, therefore, it probably has colder temperatures resulting in less melting. Table 1 shows that more snow accumulated in the winter than was lost in the summer for Glacier 3.

e. The orientation could be responsible for the difference in elevation of the equilibrium lines. Glacier 2 faces southeast and probably experiences warmer temperatures than Glacier 1, which faces north. Warmer temperatures cause more melting.

4. a. Glacier 3 is most likely advancing.

Glacier 2 is most likely retreating.

b. Glacier 3 has a positive net mass balance, thus more snow is accumulating than is being lost. Glacier 2 has a negative net mass balance, thus more snow is being lost than is accumulating.

exercise 21 - glacial landforms

part 2: Mt. Rainier, Washington

1. Composite (strato) volcano

2. White with blue contour lines.

3. a. In orange.

b. Sand and gravel.

c. Medial moraine.

d. Lateral moraine.

4. An arete.

5. a. In yellow.

b. In green

c. In pink.

6. a. Volcanic crater.

7. a. It forms a steep-sided, sharp edged ridge.

b. Whitman Crest.

c. The lower portions are light gray, indicating they are covered with sediment.

8. a. It indicates that a lot of sediment (sand) has been deposited along the river bed.

b. Braided

c. It indicates that the White River has a high sediment load; there is more sediment available for transport than the river can carry at normal flow levels.

d. The valley would be U shaped; it is a steep-sided, flat bottomed valley.

e. It was created by glacial erosion. In mountainous regions, glaciers carve out U-shaped valleys while rivers carve out V-shaped valleys.

9. a. In brown

b. In pink.

c. It is a cirque.

d. Sunset Amphitheater

10. a. It is a very steep-sided, semi-circular shaped feature.

b. It is an arete

c. change in elevation = 9700 feet - 3500 feet = 6200 feet

distance =

gradient = = 1216 ft/mi

d. No, the gradient is steepest near the head of the glacier and gentlest in the middle of the glacier.

e. A hanging valley.

f. The floor of this valley is high above the floor of the valley the Carbon glacier flows in. This is an example of a hanging valley.

exercise 21 - glacial landforms

part 3: Whitewater, Wisconsin

1. a. See map; In yellow.

b. Because it is full of kettle holes.

2. a. To the northwest; behind the moraine.

b. See map.

3. a. Outwash plain.

b. Meltwater flowing out from the glacier created this flat plain. Sediments from the glacier were deposited here. The coarsest material was deposited first and as distance from the glacier increased, progressively finer material was deposited.

4. a. Kettle holes.

b. As the glacier melted, blocks of ice broke off the main glacier. These blocks of ice were covered by sediment, which insulated them, preventing them from melting quickly. Eventually, however, the blocks melted and the overlying material collapsed into the depression left where the ice blocks were. Kettle holes may or may not contain water.

5. a. Drumlins.

b. N S

c. The ice flowed from the north to the south.