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Home , Ablation zone, Accumulation zone

Conversational Answers

Learning to speak like a glaciologist

Matching Exercise A sharp knife-edge ridge of high ground that forms between two corries where they are cutting back into the rock

A form of erosion that is caused by rocks and sediment at the abrasion base of grinding along the ground beneath acting like a giant sand-paper file to scrape and smooth rocks below

Sediment material that is dragged along the base of a bedload or , acting to erode the ground beneath

A mixture of sands, clays and boulders carried by a glacier and boulder then deposited over a large area clay (till)

As ice slowly moves forward it pushes material forwards ahead bulldozing of it like a bulldozer

The process whereby blocks of ice collapse and fall from the calving snout of the glacier, often into a glacial lagoon

An armchair-shaped rounded hollow in a mountainside that is formed by a combination of glacial erosion, rotational slip and corrie /cwm / freeze-thaw weathering. When the ice melts it leaves a depression in the rock

A deep crack found in the surface of an ice-sheet or glacier, these are often buried under snow and can be incredibly dangerous if unseen

A hill landform that is formed by the deposition of glacial till (boulder clay) as a glacier moves, they are usually oval in shape and their long axis is parallel to the direction of ice

The imaginary boundary line between the zone (where equilibrium ice is lost) and (where ice is gained) line The process of material being broken down and worn away, erosion which can happen in various ways, e.g. abrasion, , freeze-thaw

Rock sediments that are transported and deposited by a glacier at some distance from their original source location, making erratics them appear unusual in comparison to other materials nearby

A long, narrow, deep, steep-sided inlet from the sea back inland that is formed by glaciers and then later drowned once sea level rises again

Also known as frost-shattering, this is a type of erosion when freeze-thaw temperatures are near freezing point and as water enters cracks in the rocks it will later freeze, expand and then break weathering the rocks apart

glacial Also known as a U-shaped , the U refers to the deep and trough / wide shape that a valley becomes following ice erosion (unlike glaciated river valleys which are eroded to form a V shape) valley

A tributary valley that joins on to the main glacier, it is too high up and cold for ice to be able to easily move and so does hanging not become as eroded as the main glacier valley – it often has valley waterfalls today

The current epoch of geological time, that began Holocene approximately 12'000 years ago at the end of the Pleistocene; part of the Quaternary period

The period of time in between glacial periods (ice ages) when interglacial it is warmer

A narrow band of sediment debris that runs along the sides and edges of a glacier as a result of the ice eroding the valley lateral sides and freeze-thaw weathering of the rocks

Frost-shattered rock debris and sediment that is eroded from moraine the valley floor and sides then transported and deposited by glaciers Sediment, often sands and gravels, deposited by outwash streams in front of and underneath glaciers which is then sorted and rounded over time (this forms an , similar to a river forming a floodplain)

A type of erosion where glacial melt water freezes onto rocks plucking and then as the ice carries on moving it ‘plucks’ and pulls off pieces of rock

When several corries cut back into the rock back-to-back they pyramidal meet at a central point, eroding the mountain to form a steep peak pyramid shape

Long, narrow finger-shaped lakes that are found in glaciated valleys, and were formed when the glacier had more erosion energy (e.g. when the glacier moves over a band of softer rock that erodes more quickly than surrounding harder rock)

A bare outcrop of rock (that looks like a sheep head) that is shaped by roches glacial erosion to leave one side smooth and gently sloping while the moutonn other side is steep, plucked and rough ées

A process that occurs when ice flows in a circular motion, rotational helping to erode hollows and bowls in the landscape slip

Loose stones that are broken away from mountain sides by scree freeze-thaw weathering, and leave slopes covered in angular loose stones

Changes in the relative level of the sea compared to the land sea level which can fluctuate according to glacier activity, e.g. falling sea change levels during high glaciation, or rising seas during times of ice melt

The end of a glacier, which is always either advancing or snout retreating as glaciers are constantly (though very slowly) (terminus moving or toe)

A deep circular lake that forms within corries / / cwms when ice has melted I A ridge of rock / sediment debris that is deposited at the end of terminal a glacier, it is usually a mix of boulders, sand, gravel and clays moraine I x- ---- + ------� I A former river valley spur (ridge of high land) which has had truncated the ends ‘sliced’ off by a valley glacier, leaving steep cliff-like spur edges -----+------Also known as a glacial trough, the U refers to the deep and U shaped valley wide shape that a valley becomes following ice erosion by glaciers leaving a wide flat valley floor and straight sides -----+------The breakdown or decomposition of material such as rock by weathering physical (mechanical), chemical or biological processes -----+------

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I Professional Glaciology Answers

Learning to speak like a glaciologist

Matching Exercise The process of ice loss from a glacier or ice sheet usually through melting, sublimation, evaporation, , avalanche, etc.; the ablation is the area (usually at lower elevations) where net loss takes place (where melting exceeds accumulation)

The build-up of the glacier’s mass due to snow being compacted into ice; the accumulation zone on a glacier is the part of a glacier (usually at accumulation higher elevations) where there is net accumulation (where snowfall and other frozen precipitation exceeds losses)

Albedo is the reflective capacity of material to return incoming solar radiation; white surfaces such as glacial ice have a high albedo effect and albedo effect reflect much solar radiation – there is a feedback loop whereby if ice surfaces melt then more dark surfaces become exposed, leading to more rapid melting When warm glaciers have high enough temperatures at the base to produce significant meltwater this water acts as a lubricant to basal reduce friction between the base of the ice and the bedrock, sliding encouraging flow

A deep crevasse that can be found along the rear wall of a corrie (cwm / cirque) that formed as ice moves away downhill

These are found in higher latitudes and so there is less seasonal variation in temperature and less meltwater; as a result these cold-base glaciers tend to move more from internal deformation rather than glaciers

If the gradient is less steep or ice is moving over a major obstacle then the ice flow slows down and backs up on itself, which can close compressional and form fractures in the ice; the ice thickens which flow increases its mass and pressure at that point which increases erosion

Moraine (rock debris) that is carried along within the ice itself englacial moraine

This marks the line of separation between areas of equilibrium accumulation and areas of ablation, and it will move each year line

A long ridge of sediment that is deposited by meltwater from retreating ice and usually forms a winding course If the gradient becomes steeper then ice will move faster extensional downhill, in effect stretching the ice mass so that it becomes flow thinner in some points and creates cracks and crevasses at right angles to the flow Extensive areas of angular rock, from the German for ‘sea of rock’ where exposed rock surfaces that have been quickly felsenmeer broken up by frost action are found on mountain slopes (also known as blockfield)

The term for anything relating to the erosion or deposition caused by flowing meltwater from glaciers or ice sheets fluvioglacial

When soil particles on a slope move downhill due to gravity, a frost creep form of slow mass movement of soil that begins with freeze- thaw action

A form of solifluction found in periglacial environments where gelifluction the downslope sliding movement of seasonally thawed and saturated soil is assisted by an impermeable layer of permafrost beneath the topsoil

The balance between the amount of inputs compared to glacial outputs in the glacial system, typically a glacier losses mass budget through evaporation and there will be some melting at the snout in the ablation zone Glacial The response of land that was once weighted down and deformed isostatic under the ice rising and falling in reaction to the loss of ice, for rebound / example northern Scotland that was once glaciated is still rebounding adjustment and rising while to compensate the south of England is sinking

The term for a change in sea level due to the uptake or release glacioeustasy of water from terrestrial glaciers and polar ice, during times of increased glaciation or increased melting

This process takes place mostly within cold glaciers where gravity and the pressure of ice in the accumulation zone causes internal ice crystals to slide over each other and crumple and deform, deformation which can form crevasses

Hills that have an , and are usually circular or dome-like isostasy in shape; the ice in the centre accumulates due to hydrostatic pressure or groundwater flow A process of gradually moving wet soil or other material down jökulhlaup slope, particularly when frozen subsoil acts as a barrier to prevent percolation of water; a form of slow mass movement

A steep-sided flat-topped mound of gravel and sand that is / deposited by meltwater from retreating ice; the terrace forms when sediment accumulates in ponds and lakes terrace

A rounded hollow that is generally filled by a lake, that forms due to a melting ice mass that is trapped within deposits holes

The net change in a glacier’s mass over a year (or other fixed time span); this can be a positive mass balance if the glacier accumulates mass more ice than it loses through ablation (melting) and a negative balance mass balance if there is more ablation than accumulation

medial Weathered rock debris bands that run along the centre of a glacier, moraine forming when lateral from two glaciers merge together

Once all the ice has melted and a river returns to the misfit deglaciated valley, it can look unexpectedly small and out of stream place within the scale of the large wide glacial trough

A cylindrical vertical or near vertical shaft within a glacier, formed by surface meltwater percolating through a crack in the ice and scouring

Another form of ground ice, with slices of ice that penetrate needle ice down through the soil vertically – playing an important role in breaking up soil particles to loosen them for erosion and transportation

A group of processes such as freeze-thaw and mass wasting nivation serve to carve out depressions and hollows in the ground, which can enlarge over time to form corries

An area adjacent to a glacier or ice sheet that is subjected to periglacial repeated freeze-thaw processes, a cold climate that commonly has permafrost, e.g. Canada, Greenland, Siberia, etc. I Hills that have an ice core, and are usually circular or dome- pingos like in shape; the ice in the centre accumulates due to I hydrostatic pressure or groundwater flow x- ---- + ------The most recent epoch during which ice coverage was much � I greater than it is today, from approximately 2.5million years Pleistocene ago until 11’800 years ago, which ended with the present interglacial Holocene epoch -----+------The most common type of ground ice which develops in spaces - between soil particles The most common type of ground ice pore ice which develops in spaces between soil particles

-----+------Similar to , but rather than being at the - absolute furthest point of the glacier’s snout they are recessional deposited wherever the snout remained static for long enough moraine to accumulate debris

-----+------Layers of rock debris from the valley sides build up on the surface of - glaciers over time, and each successive winter it becomes embedded rotational within the growing ice; bands of slowly rotating frozen rock then scouring scrape over the bedrock to erode when ice moves downhill

-----+------A process of gradually moving wet soil or other material down - solifluction slope, particularly when frozen subsoil acts as a barrier to prevent percolation of water; a form of slow mass movement

-----+------Grooves that are scratched into the bedrock below ice as the - � glacier moves and transports material down valley; these lines striations show in what direction the ice flowed

-----+------Irregular land surfaces found in periglacial landscapes that - consist of alternating hills and hollows that are formed when thermokarst permafrost thaws

-----+------When a large portion of ice becomes detached from the main - glacier and melts, any suspended sediment within the ice will � till plains be deposited and form a large plain of unsorted till material

-----+------Glacial sediment deposits that form in thin layers in pairs of - clay and silt; these layers represent a single year (summer and varves winter deposits) in a lake and can help scientists determine the glacier chronology I I Also known as temperate glaciers these are found at lower warm-base latitudes (e.g. the Alps mountain range); temperatures around glaciers I the glacier are warmer allowing the ice to move more rapidly x- ---- + with - increased - - - liquid - -meltwater - - -and -basa -l sliding ------� I

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