Edexcel Geography A-Level - Glaciated Landscapes and Change

Flashcards on Glaciated Landscapes and Change

Glacial Period

Colder temperatures causing glacial advances and sea levels to fall.

Interglacial Period

Warmer temperatures causing glacial retreats and sea levels to rise.

Last Glacial Maximum

The most recent period of glacial advance around 21,000 years ago.

Little Ice Age

A significant global cooling period between 1300 and 1870.

Milankovitch Cycles

Earth's orbital changes (eccentricity, tilt, wobble) affecting global energy and climate.

Eccentricity

The Earth’s orbit changes from circular to eclipse every 96000 years, which changes the distance between the earth and the sun.

Tilt

The Earth’s tilt changes between 21.8 degrees and 24.4 degrees every 41000 years.

Axial Precession

Over time, the direction in which the axis tilts changes. In 22000 years, the axial tilt spins one whole time around.

Sunspots

Dark areas on the sun that increase solar output; their number varies in an 11-year cycle.

Holocene Epoch

An era of limited ice cover lasting over 10,000 years, the epoch we are currently in.

Polar environments

Located at high latitudes within the Arctic (66°N) and Antarctic Circles (66°S) or within the 10°C isotherm.

Alpine Environments

Areas of low temperatures in high altitude, mountainous regions, found at any latitudes, above the tree line.

Periglacial Environments

Areas on the edge of colder environments with permafrost (permanently frozen ground).

Permafrost

Ground that is permanently frozen.

Active Layer

The top layer of permafrost that thaws in the summer.

Nivation

Processes involving snow and ice that cause erosion.

Frost Heave

Water underneath rocks or ground freezes, expands, and thus forces the mass upwards.

Solifluction

Mass movement of waterlogged soil between the active layer and frozen permafrost, flowing due to gravity.

Accumulation

The addition of mass (usually snow) to a glacier.

Ablation

The loss of mass from a glacier (meltwater, avalanches, sublimation, etc.).

Glacial Budget

The mass balance of a glacier (difference between accumulation and ablation).

Dynamic Equilibrium

A state of balance where inputs equal outputs in a glacier system.

Positive Feedback Loop

A chain reaction where one process heightens another, exacerbating the initial process.

Negative Feedback Loop

A process that counteracts another, leading to no overall change.

Internal Deformation

The deformation of layers of ice or individual ice crystals caused by the pressure from the weight of the ice.

Compressional Flow

When ice hits a shallower gradient, friction causes the ice to slow down, build up and compress.

Extensional Flow

When ice meets a steep downhill gradient, gravity forces the ice to increase in velocity.

Rotational Slip

Compressed ice becomes trapped in a hollow, but gravity causes it to continue to move downwards. Meltwater assists in moving the glacier in a rotational movement, causing it to continually erode the hollow.

Basal Sliding

Glacier sliding over the bedrock due to meltwater lubrication.

Creep

Occurs when a glacier travels around a large obstacle (greater than 1m) by plastically deformation.

Regelation

Glacier melts under increased pressure and so the glacier accelerates due to basal slip. The glacier will refreeze on the leeside of the obstacle.

Plucking

Rocks attached to bedrock become frozen to the glacier and are pulled from the landscape.

Abrasion

A sandpapering effect caused by small rocks embedded within the glacier rubbing on bedrock.

Corrie

Bowl-shaped hollow with a steep back wall, formed by glacial erosion (plucking and abrasion).

Arête

Knife-edged ridge formed between two corries.

Glacial Trough

U-shaped valley formed by a glacier eroding a river valley.

Hanging Valley

A smaller u-shaped valley caused by a tributary glacier.

Roche Moutonnée

Mound of rock shaped by a glacier flowing over it, with a gently sloping stoss side and a steeper lee side.

Till Plain

Unsorted glacial material deposited when an ice sheet melts.

Erratics

A large boulder that is of a different rock type to surrounding rock that has been transported by a glacier and deposited.

Moraine

Deposits of eroded material transported with the glacier (lateral, medial, ground, recessional, terminal).

Drumlin

Elongated hill of glacial deposit, shaped like an inverted spoon.

Meltwater Channel

Streams of meltwater (melted glacier) formed by higher temperatures.

Kame

Mound of sorted material deposited by meltwater on a retreating glacier.

Esker

Long, winding ridge of glacial deposition, a mould of glacial meltwater channels.

Outwash Plain

A plain formed of glacial sediments deposited by meltwater at the terminus of a glacier.

Patterned Ground

Ground is formed through the frost heave of stones in and underneath the active layer.

Ice Wedge

Water infiltrates small cracks in the permafrost and expands on freezing (frost action).

Pingo

Ground is forced upwards through frost heave of an ice lens, leaving a mound. The mound can be an open or closed pingo.

Terracette

One of a series of steps on a hillside, thought to be caused by soil creep.

Solifluction Lobe

Tongue-shaped lobes of soil that fall down a slope caused by solifluction.

Blockfield

A rock-strewn landscape caused by extensive frost action of the landscape

Thermokarst

Marshy, boggy wetlands caused when permafrost melts.

Environmental Fragility

The concept of an environment being vulnerable and at risk , as it lacks the ability to be resilient and adapt to changes.

IUU Fishing

Illegal, unreported, and unregulated fishing .