Geography - Glaciation - Key Terms

System

Process that has inputs, processes and outputs. 2 types

* Open,
* Closed.

Open system

A system whose processes are influenced and changed by external factors.

Inputs

Things that go into a system - e.g. Precipitation, Snow.

Throughputs

How materials are moved within a system between inputs and outputs.

Outputs

Things that leave a system e.g. evaporation and melting.

Processes

Forces that work to form and transform landscapes. e.g. Erosion, Water cycle.

Deposition

Throughflow of a glacier loses energy and is deposited by glacier.

Erosion

Rock materials are worn away over time.

Transport

Eroded material carried by Water/Glaciers.

Mass Movement

Process of erosion, transport and accumulation of material - occur on gentle and deep slopes.

Abrasion

Erosion caused by rocks and boulders in base of glacier grinding against debris in glacier.

Plucking

meltwater freezes into cracks of rock and freezes, as glacier moves, material is dragged along by glacier.

Weathering

Processes where a rock is broken down but does not get transported and so stays in the same position.

Aeolian processes/sediment

Processes responsible for emissions of sand, forming sand dunes.

Stores

Material accumulated and stored in a glacier.

Flows

How material is moved around in a glacier.

Material

Anything from Earth in glacier.

Energy

What causes everything to move. Cannot be created or destroyed.

Mass Balance

Balance of accumulation and ablation.

Positive Mass Balance

When there are more inputs than outputs in a glacier.

Negative Mass Balance

When there are more outputs than inputs in a glacier.

Equilibrium

Balance between accumulation and ablation.

Dynamic Equilibrium

Equilibrium that changes with the seasonal variation found in warm-based glaciers.

Accumulation

Inputs going into glacier. e.g. snow and ice.

Ablation

Outputs leaving glacier. e.g. Melting and evaporation.

Sublimation

Solid becomes gas - skipping liquid.

Climate

Pattern of weather in an area.

Lithology

Physical characteristics of rock.

Structure

Hard or soft.

Geology

Structure + composition of Earth.

Latitude

Distance from equator.

Altitude

Height from sea level.

Relief

Differences in land height from place to place.

Aspect

Orientation of surface in relation to sun.

Insolation

Solar radiation in earths atmosphere or surface.

Albedo

Ability of surfaces to reflect light.

Positive feedback loop

Accelerates temperature rises during climate change.

Negative feedback loop

Slows down temperature rises - typically in ice age periods.

Diagnesis

Physical + chemical processes eroding a rock after deposition.

Firn snow

Time between the snow turning to glacier ice.

Glacial Ice

Ice that has been compacting to the point that it is very dense.

Valley glacier

Originates in valleys and goes downwards between valley walls.

Rigid Zone

Brittle area that is broken down easily.

Plastic Flow Zone

The part of the Earths crust under high pressure to prevent fracturing.

Ice Sheet

Massive area of ice that spans over 50,000km2.

Warmed based glacier

Found in lower latitudes higher altitudes - experience high levels of seasonal variation and are more likely to have a dynamic equilibrium.

Basal Sliding

Bottom and sides of glacier exceed PMP (Pressure Melting Point) causing glacier to melt and move faster - found in warm based glaciers.

Slippage

Same as basal sliding.

Creep/Regulation

Slow downslope movement of material due to a loose surface.

Bed Deformation

Process where unfrozen sediment beneath glacier deforms under glacial weight.

Internal deformation

Occurs in cold based glaciers - is the way cold based glaciers move - 2 types - Intergranular flow and Laminar flow.

Intergranular flow

When crystals in glacier re-align and move in one direction - sliding over each other.

Laminar flow

Layers of glacier slide over each other - moving the glacier in one direction.

Extending flow

Gradient becomes steeper - ice moves faster - glacier stretches and becomes thinner - forming fractures and crevasses.

Compressing flow

Gradient becomes less steep or the ice encounters a major obstacle - ice mass slows - backs up - crevasses close and there are thrust fractures as the ice mass compresses

Freeze thaw

Water goes into cracks - freezes and expand - opening cracks in rock more - until rock fully cracks.

Frost Shattering

Expansion of freezing water into intergranular spaces and fractures in a rock. Result is rock shattering.

Pressure release

Overlying rocks are removed by erosion causing underlying rocks to expand and fracture.

Oxidation

Rocks with Iron in them broken down by water and oxygen.

Carbonation

Carbon dioxide from moisture in the air reacts with carbonate minerals found in rock.

Solution

Acidic water dissolves rocks such as chalk or limestone.

Hydrolysis

The breakdown of rock by acidic water to produce clay and soluble salts.

Biological Weathering

Weathering caused by the movements of plants and animals.

Chelation

Biological process where organisms produce organic substances, known as chelates, that have the ability to decompose minerals and rocks by the removal of metallic cations.

Rock fall

Rocks broken down by freeze-thaw weathering, loosening material making it vulnerable to the elements.

Slides

Downslope movement of material that occurs along a distinctive rupture or slip surface.

Rock flour

Sediment from ground up rock and gravel particles produced during glacial erosion.

Nivation

Erosion of rock or soil by thawing and freezing of meltwater beneath and at the margins of snowbanks.

Avalanche

Mass of snow that moves down a slope.

Debris flow

Fast-moving landslides that are very dangerous to life and property happen without warning.

Supraglacial

Things that happen on the surface of the glacier.

Englacial

Happens inside the glacier.

Subglacial

At the base of the glacier.

Drift

All sediment transported by the glacier.

Till

Unsorted and unstratified sediment, deposited by glacier.

Outwash

Expansive, generally flat areas with braided rivers when glacier is melting.

Glacio-fluvial

Landforms created by glacier meltwater.

Lodgement till

Deposits beneath glacier forced into ground.

Ablation till

Material deposited by water melting when ice is stagnant.

Unsorted

Not arranged according to size.

Unstratified

Doesn’t have distinct layers.

Corrie

Horseshoe-shaped valley which is formed through erosion by ice or glaciers.

Pyramidal peak

3 or more corries backing onto each other making a peak.

Arete

2 corries backing onto each other forming knife edge.

Trough

A long and narrow or shallow channel or depression.\`\`\`\`\`

U shaped valley

Valley formed by a glacier with a flat bottom and steep sides.

Striations

Marks on rock made by glacier as rock embedded in glacier moves over it.

Roche Moutonnee

Landform made of resistant rock with a smooth slope facing direction of ice flow and steep opposite facing slope due to plucking.

Ellipsoidal basin

Former river valley widened and deepened from subglacial activity of ice sheet.

Isostatic

Local changes in sea level due to changes in amount of ice on land.

Eustatic

Rise or fall in sea levels due to a change in volume of water.

Terminal Moraine

Material deposited at the end of a glacier as a glacier recedes.

Lateral Moraine

Material deposited on the sides of the glacier.

Recessional Moraine

Secondary terminal moraine deposited when a glacier stops its recession.

Erratics

Large boulders carried by glacier that are dropped as the glacier melts and recedes. rock is normally found in middle of valleys.

Drumlins

Hills of sediment deposited as a result of friction between rocks and ice, sediment is then streamlined and given its shape by the glacier moving over the top of it. It is a subglacial landform.

Till sheets

Large plains of glacial till that is formed when ice detaches from glacier and melts, depositing sediment it carries.

Proglacial lake

Masses of water at the edge of an ice sheet or glacier.

Lobe

Curved part of a glacier or ice sheet.

Meltwater

Water released by the melting of glacial ice.