Glaciated Landscapes 1 Flashcards
System
Set of interrelated objects comprising of components (stores) and processes (links) that are connected together to form a working unit/united whole
Open system
Energy and matter can be transferred from neighbouring systems as an input and transferred to as an output
Inputs in glaciated landscape system
Kinetic from wind and moving glaciers. Thermal from heat of sun. Potential from position of material on slopes, material from deposition, weathering and mass movement from slopes and ice from accumulated snow fall
Outputs
Glacial and wind erosion from rock surfaces. Evaporation, sublimation and meltwater
Throughputs
Stores: ice, water, debris accumulation. Flows: movement of ice ,water and debris downslope under gravity
Warm based glacier characteristics
High altitude locations, steep relief, basal temp at/above PMP, rapid rates of movement (20-200m per yr)
Cold based glaciers characteristics
Hugh latitude locations, low relief, basal temp below PMP so frozen to bedrock, very slow rates of movement (few m per yr)
Pressure melting point
The point at which ice is on the verge of melting
Slippage
Ice slides over valley floor as meltwater reduces friction
Creep/regulation
Ice deforms under pressure due to obstructions on the floor. Enables it to spread over/around obstruction before re freezing when pressure reduces
Bed deformation
Ice carried by saturated bed sediments moving beneath it on gentle gradients
Intergranular flow
Individual ice crystals reorintate and move in relation to each other
Laminar flow
Movement of individual layers within the glacier - often layers of annual accumulation
Extending flow
When ice moves over a steep slope, its unable to deform quickly so it fractures forming crevasses. The leading ice pulls away from the ice behind it which has yet to reach the steep slope
Compressing flow
When gradient reduces, the ice thickens and the following ice pushes over the leading slow moving ice. Slip planes are at different angles in each course
Factors influencing the movement of ice
Gravity, gradient, thickness of ice, internal temp of ice, the glacier budget
Glacier masss balance/ budget
Difference between amount of snow and ice accumulation and amount of ablation occurring in a glacier over 1 year
Formation of glacier ice
Glaciers form when temps are low enough for snow that falls in 1 year to remain frozen throughout the year
Glaciers
Large, slow moving masses of ice
Ice sheets
Largest accumulations of ice. E.g. Antarctica and Greenland - 96% of worlds ice
Self regulation in a system
When equilibrium is disturbed, the system changes its from until equilibrium is restored
Dynamic equilibrium in a system
System produces its own response - example of negative feedback
Lithology
Describes physical and chemical composition of rocks
Weak lithology
Little resistance to erosion, weathering and mass movements. Weak bonds. E.g clay
Strong lithology
Dense interlocking crystals, highly resistant, form landforms. E.g. basalt
Structure
Concerns properties of rock types - jointing, faulting and permeability
Primary permeability
Air spaces (pores) separate mineral particles, can absorb and store water
Secondary permeability
Water seeps into rock due to many joints. Joints largened by solution
