Ch 17 Glacial and Periglacial Landscapes

Question 1

Which 2 countries does most of the snow and ice sit in the world?

Answer 1

Greenland and Antarctica

Question 2

Cryosphere:

Answer 2

portions of the hydrosphere and lithosphere that are perennially frozen, including the freshwater making up snow, ice, glaciers, and frozen ground, and the frozen saltwater in sea ice

High latitudes and high elevations

Question 3

Describe the feed back loop of increasing temperature and decreasing snow cover

Answer 3

As temperatures increase with climate change, seasonal snow cover decreases, creating a positive feedback loop in which decreasing snow cover lowers the global albedo, leading to more warming and, in turn, further decreasing the seasonal snow cover

Question 4

Snow properties:

What happens to places with high latitudes and elevations?

Answer 4

In the mid-latitudes, snow
accumulates and melts in
different cycles depending on location and weather patterns

At high latitudes and high
elevations, snow will
accumulate year over year.

Snowline: lowest elevation at which snow persists year-round

Question 5

Firn:

Answer 5

A granular, partly compacted snow that is intermediate between snow and ice

Question 6

Formation of glaciers:

Answer 6

1- Snow Accumulates: Snow falls and builds up over time, especially in winter. Each new layer adds weight on top of the older layers.

2- Pressure Builds: As more snow accumulates, the layers at the bottom are pressed harder, causing them to become denser.

3- Firn Forms: After surviving the summer, the snow becomes firn, a kind of granular, compacted snow that’s between snow and ice.

4- Glacial Ice Forms: Over many years, the firn is further compressed and crystallizes into dense glacial ice due to continued pressure from above.

Question 7

Alpine glaciers:
(type of glacier)

Answer 7

A glacier in a mountain
range is an alpine glacier or mountain glacier.

Four common subtypes:

1- Cirque glacier - glacier in a bowl- shaped recess at the head of a valley

2- Valley glacier - in steep-walled valleys

3- Piedmont glacier - at the base of a mountain range

4- Tidewater glacier (or tidal glacier) - a glacier ends in a body of water
influenced by tides

Question 8

Continental glaciers, ice sheets, and ice fields:

Answer 8

1- A continuous mass of ice with a much larger scale than individual alpine glaciers is a continental
glacier.

An ice sheet is a mass of glacier ice that covers an area of more than 50,000 km2. Two major ice sheets
are Antarctic and Greenland ice sheets.

Two additional types of continuous ice cover associated with mountain
locations are ice caps and ice fields.

Question 9

glacier at equilibrium:

Answer 9

incoming snow = melt rate

Therefore, glacier remains its size

Question 10

Glaciers are open or closed systems?

Answer 10

Open system, inputs are snow and outputs are ice, melt water, and water vapor

Question 11

Firnline:

Answer 11

Where the accumulation zone ends, and summer melting occurs below this line

Question 12

Ablation:

Answer 12

Loss of glacial ice through melting
sublimation
iceberg calving
wind erosion

Question 13

Accumulation:

Answer 13

The addition of mass to a glacier through

• Snow, hail, freezing rain
• Avalanching of snow from adjacent slopes

Question 14

Glacial Mass balance:

Answer 14

Advance:
Gains exceed losses (accumulation > ablation); glacier thickens and extends at the terminus, equilibrium line moves
down

Losses exceed gains (accumulation < ablation); glacier thins and retreats at the terminus, equilibrium line moves up

Question 15

Where does deformation occur in a glacier?

Answer 15

Deformation occurs internally, below the rigid surface layer, which fractures as the underlying plastic zone moves forward

Question 16

Basal slip:

Answer 16

Basal slip is when a glacier slides over the ground beneath it instead of just deforming under its own weight. This happens when the ice at the bottom is warm enough to melt slightly, creating a layer of water or slush that acts as a lubricant, making it easier for the glacier to move

Question 17

Glacial erosion:

Answer 17

plucking: The glacier lifts and removes rocks from the ground as it moves, carrying the debris either on its surface or within the ice itself

Abrasion: Rocks frozen into the glacier’s base scrape and smooth the surface beneath, polishing the exposed rock and leaving grooves or scratches (glacial striations) in the direction of the glacier’s movement

Question 18

Roche moutonnee

Answer 18

An erosional landform, from plucking + abrasion, asymmetrical hill of bedrock with gently smooth upslope and a rough downslope

Question 19

Fjord:

Answer 19

A deep, narrow valley filled with seawater, created when a glacier carves a path to the ocean and then melts away. As the glacier retreats, the sea floods the valley.

Question 20

Glacial drift:

Answer 20

The general term for all glacial deposits, both unsorted and sorted

Question 21

Moraines:

Answer 21

Depositional landforms

A glacier carries rocks and debris on top, inside, or at its bottom as it moves. When the glacier melts, it drops everything in a jumbled pile on the ground.

Medial moraine is when 2 moraines meet

terminal moraine: occurs at a glaciers endpoint

Question 22

till plain

Answer 22

A deposition of till that forms behind a terminal moraine as the glacier retreats and is generally spread widely across the ground surface, creating irregular topography

Question 23

Glacial outwash:

Answer 23

Milky white water owing to the sediment load of fine-grained materials, known as “rock flour.”

Question 24

Periglacial:

Answer 24

A result of geomorphic processes related to freeze-thaw cycles of rock and frost action.

Periglacial land is an area with permafrost that is not covered by glaciers

Question 25

Permafrost:

Answer 25

When rock or soil temperatures remain under 0 degrees for at least 2 years, perennially frozen ground forms.

Question 26

2 types of permafrost:

Answer 26

Continuous:
1- Found in the coldest areas, where it stays frozen year-round.
2- Covers almost all surfaces except under deep lakes or rivers.
3- Can be up to 1000 meters deep.

Discontinuous:
1- Found in slightly warmer areas, where patches of permafrost are mixed with unfrozen ground.
2- More likely to thaw with climate change, especially on warmer slopes or under insulating snow.

Question 27

Frost action processes:

Answer 27

Frost heaving: Soil and rocks pushed upward.

Frost thrusting: Soil and rocks pushed sideways.

Ice wedges: Cracks in frozen ground fill with water, which freezes and expands.

Answer 28

Solifluction
General process: Refers to the slow downhill flow of waterlogged soil.

Occurs in: Any environment where soil becomes saturated, not necessarily in permafrost areas.

Key cause: Thawing and water saturation in the active layer, without the presence of ground ice

Gelifluction
Specific process: A type of solifluction that occurs in areas with permafrost or ground ice.

Occurs in: Periglacial environments (cold regions with permafrost).

Key cause: Movement of the thawed active layer over a frozen or icy base, which acts as a barrier, enhancing the flow.

Question 29

The Pleistocene
Epoch

Answer 29

A 1/3rd of Earth’s surface was buried
beneath ice sheets and glaciers.

Began 2.5 million years ago

Question 30

Ice age landscapes

Answer 30

Ice age (or glacial age) – any extended period of cold (can last millions of years).

Includes glacial (advance) and interglacial (retreat) periods.

The last glacial period ended ~7,000 years ago.