Glaciers

Question 1

Define Ablation

Answer 1

All processes by which snow and ice are lost from a glacier, floating ice, or snow cover; or the amount which is melted. These processes include melting, evaporation, (sublimation), wind erosion and calving.

Question 2

Abrasion?

Answer 2

The mechanical wearing or grinding away of coo surfaces by the friction and impact of rock particles transpired by wind, ice, waves, rubbing water, or gravity.

Question 3

Accumulation?

Answer 3

All processes that add snow or ice to a glacier or to locating ice or snow cover: snow fall, avalanching, wind transposed, refreezing.

Question 4

Albedo?

Answer 4

The percent of the incoming radiation that is reflected by a natural surface such as the ground, ice, snow, water. Atmospheric albedo includes clouds and particulates in the atmosphere. Synonym: reflexivity.

Question 5

Alpine glacier?

Answer 5

Any glacier in a mountain range which is dominantly confines by the surrounding topography. It usually originates in a cirque and may flow down into a valley previously carved by a stream.

Question 6

Calving?

Answer 6

Breaking off and floating away as icebergs of either a tidewater glacier or an ice shelf. Calving is a very efficient form of ablation, this helps stabilise the extent of ice sheets (like Antarctica) which might otherwise expand continuously from a positive mass budget.

Question 7

Crevasse?

Answer 7

A crack in a glacier caused by rapid extension. Crevasses over 10m deep would be healed by internal flow, but much deeper crevasses can be maintained by continued tension.

Question 8

Eccentricity?

Answer 8

The degree to which the Earth’s orbit around the sun varies from a perfect circle - it ranges between about one percent and five percent across a 100,000 year cycle.

Question 9

Esker?

Answer 9

A sinuously curving, narrow deposit of coarse gravel that forms along a meltwater stream channel, developing in a tunnel within or beneath the glacier. The ice-contact margins on the esker are often slumped and mixed with till.

Question 10

Firn?

Answer 10

A transition form between snow and glacial ice resulting from a summer’s consolidation, metamorphosis and melt/refreeze.

Question 11

Frost action (freeze thaw)?

Answer 11

The mechanical weathering process caused by repeated freezing and thawing of water in pores, cracks, and other openings, usually at the surface.

Question 12

Glacial ice?

Answer 12

Compacted and inter grown mass of crystalline ice with a density of 830-910 kg-m-3.

Question 13

Glacial milk?

Answer 13

Term used to deceive a sediment laden glacial stream. The stream described us usually laden with silt particles ghat are a result of glacial a abrasion.

Question 14

Glaciation?

Answer 14

A long period of time (10000+ years) characterised by climatic conditions associated with maximum glacial extent.

Question 15

Greenhouse effect?

Answer 15

Warming of global climate by retention of outgoing (long wavelength) radiation - inferred time be happening at present because of increasing atmospheric Carbon dioxide content (CO2) driven by combustion of fossil fuels.

Question 16

Ice cap?

Answer 16

A dome-shaped cover of perennial ice and snow, covering the summit area of a mountain mass so that no peaks emerge through it, or covering flat landmass such as an artic island; spreading outwards in all directions due to its own weight; and having an area less than 50000 square kilometres.

Question 17

Ice fall?

Answer 17

A region in a glacier where rapid extension (as down steep slopes) causes brittle failure and intense crevassing.

Question 18

Ice field?

Answer 18

An extensive area of interconnected glaciers in a mountain region, or a pack of ice at sea.

Question 19

Ice sheet?

Answer 19

A glacier of considerable thickness and more than fifty thousand km*2 in area, forming a continuous cover of snow and ice over a land surface, spreading outward in all directions and not confined by the underlying topography. Ice sheets are now confined in polar regions (as in Greenland and Antarctica), but during the Pleistocene Epoch they covered large parts of North America and Northern Europe.

Question 20

Ice shelf?

Answer 20

A continuous play of floating ice, which often extends seaward from a glacier or ice sheet on the shore.

Question 21

Insolation?

Answer 21

Incoming solar radiation. Short wavelength radiation - a major component of a glaciers energy balance.

Question 22

Interglaciation?

Answer 22

A long period of time (10000 + years) characterised by climatic conditions associated with minimum glacial extent.

Question 23

Joint?

Answer 23

A fracture of rock without displacement (displacement defines faulting). Jointing of bedrock by pressure release, thermal stress, frost action, and chemical weathering between glaciations allow rapid, effective erosion during glaciations.

Question 24

Jokulhulp?

Icelandic

Answer 24

Outburst flooding from a glacial ice dam breaker or intense melt, as by volcanic activity.

Question 25

Kame?

Answer 25

A deposit, composed largely of material sorted by moving water, formed in direct contact with glacier ice.

Question 26

Kame Delta?

Answer 26

A deposit, often triangular, formed where a glacial stream entered into a proglacial lake. The ice-contact margin of the kame delta is often slumped and mixed with till.

Question 27

Kame Terrace?

Answer 27

A deposit, often sloping down valley more steeply than the valley floor, formed where a glacial stream ran along a glacier margin. The ice-contact margin of the kame is often slumped and mixed with till.

Question 28

Kettle?

Answer 28

Forms when an isolated block of ice persists in a ground moraine, and out wash plain, or valley floor after the glacier retreats; as the block melts, it leaves behind a steep-sided hole that is filled with water.

Question 29

Latitude?

Answer 29

Angular distance of a point in the weather surface, North or South of the equator, measured along a meridian, the equator being latitude 0• , the North Pole latitude 90•N and the South Pole 90•S.

Question 30

Maritime glacier?

Answer 30

A glacier in close proximity to open ocean water, this dominated by high accumulation and ablation.

Question 31

Mass budget?

Answer 31

On an annual basis, the difference between mass gained through accumulation and mass lost by ablation.

Question 32

Orograohic uplift?

Answer 32

Uplift of air masses encountering mountain ranges. As with convective and frontal uplift, causes cooling, this precipitation. Unlike convective and frontal uplift, it is fixed in space, this causes areas of high local precipitation, this glacier growth.

Question 33

Outwash?

Answer 33

Meltwater-deposited sediment, dominantly sand and gravel, showing increasing rounding and sorting into layers with increasing distance from the ice margin.

Question 34

Outwash plain?

Answer 34

A plain of glaciofluvial deposits of stratified drift from meltwater-fed, braided, and overloaded streaks beyond a glacier’s morainal deposits.

Question 35

Pleistocene?

Answer 35

The epoch that extended from about 1.8million years ago to 10,000 years ago in the geologic time scale; when most recent glaciations occurred.

Question 36

Plucking?

Answer 36

A process of glacial erosion by which blocks of rock are loosened, detached, and borne away from bedrock by the freezing of water in fissures.

Question 37

Polar climate?

Answer 37

A type of climate of latitudes greater than sixty six degrees characterised by temperature of 10 degrees Celsius and below. The two types of polar climates in Koppen’s classification are tundra climate and perpetual forest climate (temperature always below zero degrees Celsius).

Question 38

Sea ice?

Answer 38

Ice which covers ocean or sea; includes mostly continuous pack ice, broken only by narrow open water.

Question 39

Snow?

Answer 39

Distinct crystals (of many forms) of ice.

Question 40

Stratified Drift?

Answer 40

Sediments deposited by glacial meltwater that’s are sorted and layered; a major subdivision of glacial drift includes river, lake and marine deposits.

Question 41

Striations?

Answer 41

Multiple scratches or minute lines, generally parallel but occasionally cross cutting, inscribed on a rock surface by a geologic agent. Common indicators of (at least the latest) direction of glacier flow.

Question 42

Till?

Answer 42

Deposits of a glacier - usually described as massive (not layered), poorly-sorted, and composed of multiple types of angular to sub rounded rocks, but varying greatly with source material.

Question 43

Trough? Or U shaped valley

Answer 43

The steep walled, broad floored shape considered diagnostic of former mountain glaciation. Often contrasted to the V shape typical of mass wasting slopes feeding river systems.

Question 44

Valley Glacier?

Answer 44

A subtype or alpine glacier or mountain glacier, which is longer than it, is wide, and flows along the floor of a mountain valley.