Lecture 21

Question 1

Glacier

Answer 1

Accumulation of ice affected by past or present movement.
Snow falling in winter exceeds snow melting in summer, so layer left at end of the year, then another year, etc.
Snow turns to ice. Thick ice flows under its own weight.

Question 2

Continental glaciers

Answer 2

Cover large areas, like Antarctica and Greenland.

Question 3

Alpine glaciers

Answer 3

Found in mountainous areas.

Question 4

Quaternary

Answer 4

The last 2.6 million years, designated as the time of ice ages.
Broken up into two time periods.

Question 5

Pleistocene

Answer 5

Majority of the Quaternary.

Question 6

Holocene

Answer 6

Roughly the last 10,000 years (when humans developed agriculture, cities, and civilizations).

Question 7

Glacier Mass Balance

Answer 7

Accounting system for gains and losses of ice.

Question 8

Accumulation

Answer 8

Gain. Snow, rain, avalanches.

Zone of accumulation; part of glacier where accumulation exceeds ablation.

Question 9

Ablation

Answer 9

Loss. Melting, sublimation, calving (results in icebergs).

Question 10

Plucking

Answer 10

Ice melts at base, liquid water gets in cracks in bedrock and refreezes; rocks break free and carried away by ice.
Form of glacial erosion.

Question 11

Scour

Answer 11

Rock particles at base wear way bedrock surface. Glacial erosion.
Fine material; glacial polish.
Big particles; striation.

Question 12

Cirque

Answer 12

At upper part of alpine glacier, plucking erodes the headwall, forming amphitheater-shaped cirque.

Question 13

Arête

Answer 13

Adjacent cirques may form a sharp ridge.

Question 14

Horn

Answer 14

Three or four cirques may form a sharp peak.

Question 15

Hanging valleys

Answer 15

After glaciers go away, tributary valleys may be at a different level.

Question 16

Lateral moraine

Answer 16

Top of alpine glaciers gets sediment dumped on it. Here it is dumped on side.

Question 17

Medial moraine

Answer 17

Here is dumped in the middle (from lateral moraine merging when tributary joins).

Question 18

Terminal moriane

Answer 18

Most glacial sediment gets transported to front of glacier and dumped. Here deposit left at furtherest extent of glacier.

Question 19

Recessional moraine

Answer 19

Deposit left as glacier is retreating, usually where it stops for a time or advances some.

Question 20

Drumlins

Answer 20

Streamlined hills formed beneath glaciers, often found in groups.

Question 21

Kettle

Answer 21

Block of ice buried by sediment, when ice melts, depression remains.

Question 22

Erratics

Answer 22

Boulders deposited far from their bedrock source.

Question 23

Eskers

Answer 23

Sinuous ridge of sediment deposited by stream under ice.

Question 24

Isostatic rebound

Answer 24

During an ice age, weight of ice causes the crust to sink. When ice leaves, the crust rises.

Question 25

Periglacial

Answer 25

Very cold, but not ice covered landscape.

Question 26

Permafrost

Answer 26

Permanently frozen ground; most soil moisture does not melt.

Question 27

Patterned ground

Answer 27

Polygons (lines of bigger rocks) develop on ground surface. Somehow related to freezing and thawing of active layer, large rocks moved around and accumulate in lines.