Glaciated landscapes Glossary Flashcards
Glacier
Compressed snow. Ranging from 1km to the scale of Antarctica
Glaciated landscape
A landscape that has features to form a glacier. These can be active or a relic landscape
Ablation
Loss of mass- ice
Accumulation
More mass- ice
Zone of accumulation
Greater amounts of accumulation than ablation
Zone of ablation
Greater amounts of ablation than accumulation
Equilibrium line
Separates the 2 zones of accumulation and ablation
Glacial mass balance
Difference between the amount of snow and ice accumulation and the amount of ablation occurring in a glacier over a year
System
Set of interrelated elements comprising of components (stores) and processes (links) that are connected together
Pressure melting point
Refers to the temperature at which ice is at the verge of melting
Basal sliding
Sliding of glacier over bedrock
Regelation (or creep)
The base of the ice meets a rock outcrop on the valley floor the ice may flow around it
Intergranular slip
Weight of ice can result in ice crystals changing shape due to compaction. Ice crystals become flattened and slide over each other
Laminar flow
Ice flow in layers
Rigid zone
Upper zone of thew glacier where the ice is brittle and breaks
Plastic zone
Lower zone of the glacier where the under the pressure the ice deforms
Freeze thaw
Process of weathering caused by water, confined in rock joints, expanding as it freezes
Plucking
Rocks and stones become frozen to the base or sides of glacier and are plucked from the ground
Abrasion
Process of erosion whereby stones and rocks become embedded in the base and sides of the glacier
Opened system
Matter and energy can be transferred
Corrie
Armchair shaped hollow found on upland hills or mountains
Geomorphic processes
Natural mechanisms of weathering, mass movement, erosion, transportation and deposition
Weathering
Breakdown of rocks
Erosion
Wearing away or removal of rock
Physical weathering
Breakdown of rock by physical processes
Chemical weathering
The decay of rocks as a result of chemical weathering
Biological weathering
May consist of physical actions such as growth of plant roots
Oxidation
Minerals in rocks react with oxygen, either in the air or in water.
Frost shattering
Extremely low temperatures water trapped in rock pores freezes and expands
Solution
Mineral dissolves in water
Hydration
Water molecules added to rock minerals create new minerals of a larger volume
Tree roots
Tree roots grows into cracks or joints in rocks and exert outward pressure
Carbonation
Rainwater combines with dissolved carbon dioxide from the atmosphere to produce a weak carbonic acid
Organic acids
Produced during decomposition of plant and animal litter
Hydrolysis
Chemical reaction between rock minerals and water
Pressure release
The weight of the overlying ice in a glacier is lost due to melting
Supraglacial debris
Carried on the surface of a glacier. Comes forms weathering and mass movement
Englacial debris
Carried within the glacier. Comes from surface debris which has fallen down a crevasse
Subglacial debris
Transported at the base of the debris. Comes mainly from plucking and abrasion
Glacial till
Material deposited directly by the ice
Glacio-fluvial material
Deposited by meltwater
Lodgement till
Material deposited at the base of advancing glaciers due to basal melting
Ablation till
Material deposited as the ice melts away from retreating glaciers
Angular or sub-angular
In shape
Unsorted material
Large fragments and small debris
Unstratified
No sign of layering
No orientation
Rock fragments are no aligned in the same direction
Ribbon lake
A long narrow, finger-shaped lake, usually found in a glacial trough
Rock Bar
A rid or outcrop of rock either side of rock basin variations
Rock Basin
An over deepened section of the floor of the glacial trough
Rock Flour
Very fine material produced by abrasion
Rochee Moutonnee
A mass of resistant rock on the floor of a glacial trough which is smooth and rounded on the stoss (or up the valley side)- often with striation marks showing direction of ice movement
Striation
Scratches or gouges cut into the bedorck by glacial abrasion
Till
material deposited directly by the ice
Pyramidal peak
an angular, sharply pointed mountain top sometimes described as a horn shaped summit
Nivation
is a glacial process that is not easily classified as erosion or weathering
Arete
a narrow, steep sided ridge often called a knife edge ridge
Corrie
Is an arm-chair shaped hollow found on the upland hills or mountain sides. They have a steep back wall, an over-deepened basin and a rock lip at the front
Hanging valley
A smaller tributary valley to the side of the main glacial trough, left ‘hanging’ above the main u-shaped val;ley. A waterfall can be seen
Mass movement
Is the down slope transportation of material under gravity
Glacial trough
A u-shaped valley with steep, straight sides and a flat rounded bottom, carved out from a glacier
Geomorphic processes
natural processes relating to the formation and shaping of landforms and landscapes
Drumlin
A mound of glacial debris that has been streamlined into an elongated hill
End Moraine
The collective term for the three types of moraine ridge that can be formed from deposition at the snout
Erratic
An individual piece of rock, varying from a small pebble to a large boulder which is composed of different geology from the area in which it has been deposited
Lateral Moraine
A ridge of till running along the glacial valley
Medial Moraine
A ridge of till running along the middle of a glacial valley
Moraine
Moraine is used to refer to an accumulation of a glacial till to form a ridge
Push moraine
Till which has been shunted up into mound. Therfore the long axis of the individual stones may be orientated upwards from their original horizontal position
Recessional Moraine
A series of ridges running transversely across glacial troughs and which are broadly parallel to each other and to the end moraine. They are found further up the valley than the terminal moraine
Terminal moraine
A ridge of till extending across a glacial trough.
Till sheets
Formed when a large mass of un-stratified drift is deposited at the end of a period of ice sheet advance, which smooths the underlying surface
Hummocky moraines
Moulds of glacial till left by retreating corrie glacier
The skiddaw Group
Mainly slates and not resistant to weathering and erosion
The Windermere Group
Mainly sedimentary rocks which are least resistant to weathering and erosion
The Borrowdale Volcanic
Igneous rocks which are resistant rocks
Ice sheet
Large accumulations of ice which bury the landscape beneath. They extend for more than 50,000
