Glossary: Ice On The Land Flashcards
Arête.
Sharp-edged two-sided ridge on the top of a mountain.
Basal Sliding.
The act of a glacier sliding over the valley floor, due to melt water under the ice acting as a lubricant.
Boulder clay.
The name given to all materials deposited by ice; usually it is clay containing boulders of different sizes within it.
Erratic.
Boulders found on the surface that are different from the rock below.
Firn.
Crystalline or granular snow found on the upper part of a glacier, where it has not yet been compressed into ice.
Glacial trough.
The flat-floored and steep-sided valley formed by a glacier, often also referred to as a U-shaped valley.
Ground moraine.
Surface deposits left by glaciers and ice sheets; the surface formed is uneven and hummocky.
Ice cap.
A smaller body of ice (less than 50,000km2) usually found in mountainous regions.
Ice sheet.
A large body of ice over 50,000km2 in extent, usually covering all the land in an area.
Abrasion (glacial).
A process of erosion in which rocks carried in the bottom of the ice wear away the surface rock over which the the ice passes.
Lateral moraine.
Pile of scree and boulder clay deposited in a line along the sides of a valley.
Medial moraine.
Pile of loose material carried and deposited in the centre of the ice.
Milankovitch Cycles.
A theory that describes the collective effects of changes in the Earth’s movements upon its climate.
Misfit stream.
Small river which flows over the wide floor of a glaciated valley; its size is out of scale with that of the valley.
Moraine.
All materials deposited after having been transported by ice.
Pleistocene.
Geologists’ name for the last Ice Age when ice covered much larger areas of Europe, North America and Asia than it does today (1.8 million to ~ 10,000 years ago).
Plucking.
A process of erosion in which blocks of rock are torn away from the bed rock as the ice moves away.
Striations.
Deep grooves and scratches on surface rocks made by the sharp edges of stones carried in the bottom of the ice.
Terminal moraine.
Pile of boulder clay in a line across the valley or lowland, dumped by the ice at the furthest point reached.
Till (glacial).
All materials deposited by ice; it is an alternative term for boulder clay.
Valley glacier.
A moving mass of ice confined within a valley.
Corrie.
A circular ‘armchair-shaped’ rock hollow high on a mountainside, surrounded by steep and rocky walls but with a rock lip on the open side.
Drumlins.
Egg-shaped hills made of boulder clay up to 40m high and 400m long; many usually occur together forming ‘baskets of eggs’ scenery.
Hanging Valley.
A tributary valley left high above the main valley floor so that its stream flowing down the main valley sides falls as a waterfall.
