L17: Cryosphere pt. 2

Question 1

Till

Answer 1

the poorly sorted sediment left behind by glaciers. If till is reworked by meltwater beyond the terminus of a glacier, it can be redeposited as outwash

Question 2

Moraine

Answer 2

ridged accumulations of till that form as a glacier advances and retreats. There are several types of moraines that can form in a glacial landscape, and their height can vary from meters to hundreds of meters

Question 3

What happens as glaciers move along the landscape?

Answer 3

they erode the underlying bedrock and accumulate material that falls on them. In areas of ablation (below the equilibrium line of a glacier), considerable deposition of this material occurs at the base and margins of the glacier

Question 4

What are the 3 most common moraine types

Answer 4

Medial, terminal, lateral

Question 5

Medial moraines

Answer 5

form at the margin where two glaciers meet

Question 6

Terminal moraines

Answer 6

a type of end moraine that forms at the terminus of a glacier, and marks its furthest advance

Question 7

Lateral moraines

Answer 7

a type of end moraine that forms at the sides of a glacier.

Question 8

Drumlins

Answer 8

elongated and asymmetrical hills that form near the terminus of glaciers by the action of glacial ice on underlying unconsolidated sediments. The ice flow direction was from the steep side toward the shallow side of the drumlin

Question 9

Eskers

Answer 9

ridges of well-sorted sand and gravel that are formed by rivers flowing beneath glacial ice

Question 10

Kettles

Answer 10

closed basins formed by the melting away of a mass (block) of underlying glacial ice

Question 11

Kames

Answer 11

piles of sand and gravel that were accumulated in streams and lakes on top of glacial ice, and is deposited on the land surface when the glacier retreats

Question 12

Proglacial lakes

Answer 12

As the last ice age was ending, glacial lakes formed on the top of the ice sheet and at the margin

Question 13

Permafrost

Answer 13

permanently (perennially) frozen ground, that contains ice that froze during past glaciations

Question 14

Where is permafrost its thickest?

Answer 14

Perhaps counterintuitively at first glance, permafrost is thickest in areas that were not covered for long periods by insulating ice sheets during glaciations, but were instead exposed for long periods to colder air temperatures

Question 15

There’s an _________________ on top of permafrost that melts in the summer, while the underlying permafrost is __________. What does this mean in regards to construction?

Answer 15

• Active layer
• Impermeable
• Construction directly on top of permafrost can cause it to melt over time, leading to structural problems

Question 16

Pingos

Answer 16

The cyclical freezing and thawing cycles each year lead to the formation of patterned ground (ice-wedge polygons), and to frost heaving that creates small hills

Question 17

Sea ice

Answer 17

• can form when the air temperature falls below the freezing point of seawater, at approximately -2oC
• Frazil ice initially forms
• Melting and sublimation constantly remove ice from the surface of sea ice

Question 18

Frazil Ice

Answer 18

• Initially small needles of frozen and pure H2O
• Frazil ice eventually freezes together to form a continuous ice cover, and subsequent freezing at the base adds thickness

Question 19

Sea ice can be annual or perennial. What do these mean?

Answer 19

• annual – meaning it forms and then melts in a year

- perennial – meaning it lasts for at least several years

Question 20

What occurs to seawater when sea ice freezes?

Answer 20

As sea ice freezes, salt in the remaining seawater is concentrated. The resulting water is cold and denser, and flows downward into deep ocean basins, driving deep ocean circulation

Question 21

How does sea ice have a profound impact on climate?

Answer 21

(1) isolating ocean water from the atmosphere, preventing heat exchange,
(2) its high albedo, causing it to reflect light and heat
(3) contributing to the steep temperature gradient between the poles and the equator that drives atmospheric circulation

Question 22

What are the effects of ice on sea level?

Answer 22

The melting of floating sea ice would have little impact on global sea levels. However, the melting of land based ice (the ice sheets) would raise global ocean levels by an estimated 63 – 75 meters, resulting in catastrophic change