KEY TERMS OF GLACIATION - Geography

Periglacial environments

Found on the fringes of polar or glacial environments. These areas experience permanent frozen ground ( Permafrost). NOT PERMANENTLY COVERED BY ICE

Valley glacier

A glacier that flows for all or most of its length within the walls of a mountain valley

Ice sheet

Cover vast areas with ice, they aren’t in mountainous areas. Formed in areas of high latitudes and can form in low altitudes. Have to be 50,000 square kilometers.

Permafrost

Soil or underwater sediment which is a continuous sheet of frozen ice and only classifies as permafrost after being under 0 degrees celsius for two years

Discontinuous permafrost

Broken up into separate areas. Sometimes it stays all year in the shadow of a mountain

Open systems

Inputs and outputs of energy + matter eg. Drainage basin systems

Closed system

Only inputs and outpurs are energy eg. Global scale water cycle. Water never leaves our atmosphere, it gets recycled. Nothing physical enters or leaves the system

System

Set of interrelated components working together that are made up of inputs, outputs , stores and flows/transfers

Feedback

If an input increases without the corresponding output changes, then the equilibrium is upset

Negative feedback

Where the effects of the change are reduced by subsequent knock on effects. It goes back to equilibrium

Positive feedback

Where the effects of the change increase as a result of the change continuing. THIS IS BAD

Transportation

The movement of material by the kinetic energy of a medium such as water, wind or ice

Aeolian

Erosional,transportational and depositional process by the wind

Precipitation

Any form of water that falls from the atmosphere to the land or ocean

Mass balance

Total sum of all the accumulation and melt or ice loss across an entire glacier

Altitude

The height of an object or point in relation to sea level or ground level

Latitude

The distance of a place, North of South of the equator

Ice shelves

Extension of the main glacier to the to the ocean

Basal sliding

When the glacier slides over the bed as a result of meltwater at the base, which acts as a lubricant

Slippage

When the ice slides over the valley floor due to meltwater reducing friction, as a result of the glacier being above its PMP

Creep/regulation

When ice deforms under pressure due to obstructions on the valley floor which enables it to spread around and over the obstruction, re freezes

Bed deformation

As glaciers flow over soft sediments, the movement of the ice mass above results in the sediments below being ground down and dragged along the direction of flow.

Inter granular flow

Individual ice crystals re- orientate and move in relation to another

Laminar flow

Movement of individual layers within a glacier. Eg. Textbooks

Glacial surges

When the critical mass is reached in the accumulation zone and the ice moves 10 to 100 times its normal velocity

Relief

The height and shape of land

Aspect

Direction the slope faces

Microclimate

Local climate whose main characteristics are determined by topography and land use

Geology

The specific rock type in an area. The sub - catagories are lithology and strucutre

Jointing

Joints form due to stress being applied by moving ice along pre existing zones of weakness in the rock

Bedding

As the pressure of the glacier increases, the individual ice grains slide past one another causing the ice to move downhill.

Faulting

When rocks crack and form joints. Geological characteristic which means that the rock is more susceptible to freeze thaw and physical processes

Weathering

The breakdown and disintegration of rock in situ

Mechanical/physical weathering

Physical processes effect the rock, such as changes in temperature or when the rock is exposed to the effects of wind, rain and waves

Active layer and what does it release

When the surface layer melts in the summer. Lots of water is released, which create many landforms

Continuous permafrost

Permanently frozen areas. Occurs in the coldest regions and can reach up to 1,500 m in depth, which prevents melting

Sporadic permafrost

Permafrost produced in isolated spots that can only just reach the temperatures to freeze. Mean temperatures are around 0 degrees celsius. The active layer melts easily due to more energy being transported to the active layer from the radiation of heat from the talik.

Congelifluction

Any flows of earth within still frozen permafrost

Recessional moraine

shows how the glacier retreats and advances as it responds to changes in climate

Lateral moraine

As the glacier flows down a valley, the glacier erodes the sides of the valley which made it steeper, allowing rock falls to occur. It creates a ridge of deposited material that runs alongside the glacier, and meets in the middle to join the terminal moraine

Example of lateral moraine

A lateral moraine left by the retreating Athabasca glacier in Canada is 1.5 km long and 124m high

Example of erratics

Norber erratics, Yorkshire England

Drumlin

Mound of glacial debris that has been streamlined into a elongated hill

Example of a till sheet

East Anglia, the till is chalky due to the rocks that were passed by the ice. 30 - 50 m deep and was formed by several different ice sheet advances

Pressure melting point

The temperature at which ice is on the verge of melting. At the surface, this is 0 degrees celsius, but within an ice mass it will be fractionally lowered by increasing pressure.

extending flow

Eskers

Eskers are long, sinuous ridges made from glacial till deposited on valley floors by glacial meltwater flowing through subglacial and englacial tunnels.

Example of Esker

Dahlen esker in North Dakota, USA.

Example of an Outwash plain

Kelling Heath, Norfolk

Capillary action

the movement of water through the soil

Usual diameter of stone polygons

1-5 m

Precipitation levels in two different locations?

Vostock station in Antarctica has a mean annual precipitation total of only 4.5 mm. However, high altitude locations have much higher totals, such as in Jasper National Park in the Canadian Rockies having 600mm per annum of precipitation

Discontinuous permafrost

Permafrost that doesn’t cover all of the ground and the active layer melts easily because the talik can radiate more heat onto it

How can an ocean facilitate discontinuous permafrost?

Ocean acts as an insulator, which produces more taliks

Difference between sporadic permafrost and discontinuous permafrost

Discontinuous permafrost refers to areas where 50-90% of the surface is underlain by permafrost, while sporadic permafrost signifies areas with 10-50% permafrost coverage

What is artesian pressure

This pressure is a result of the water being trapped between layers of rock, creating a pressurized environment which in turn, causes the ground water to rise to the surface

Why does the stones have a lower specific heat capacity than the soil, and how does this affect patterned ground formation

These have a lower specific heat capacity than the soil that they are in due to the fact that they react to changes in temperature quicker than the soil. In winter, the stones become very cold, making the surrounding soil cold and freezing any moisture, facilitating the ice lens.