Moraine refers to any glacially formed accumulation of unconsolidated debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age. An ice age is a period of long-term reduction in the Temperature of the Earth 's surface and atmosphere resulting in an expansion of continental Ice sheets This debris may have been plucked off the valley floor as a glacier advanced or fallen off the valley walls as a result of frost wedging. Plucking, in the sense relating to Glaciers is when a glacier erodes away chunks of Bedrock to be later deposited as Glacial erratics Glacial plucking "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. Moraines may be composed of silt like glacial flour to large boulders. Rock flour, or glacial flour, consists of clay-sized particles of rock generated by glacial erosion or by artificial grinding to a similar size The debris is typically angular. Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted. Moraines may also occur when glacier or iceberg transported rocks fall into the sea as the ice melts. An iceberg is a large piece of freshwater Ice that has broken off from a snow-formed Glacier or Ice shelf and is floating in open water
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Types of moraines
Lateral moraines
Lateral moraines are parallel ridges of aids deposited along the sides of a glacier. Mono Lake is an Alkaline and hypersaline lake in California, United States that is a critical nesting habitat for several bird species and is California ( is a US state on the West Coast of the United States, along the Pacific Ocean. The United States of America —commonly referred to as the The unconsolidated debris is deposited on top of the glacier by frost shattering of the valley walls and from tributary streams flowing into the valley. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. The till is carried along the glacial margin until the glacier melts. Because lateral moraines are deposited on top of the glacier, they do not experience the postglacial erosion of the valley floor and therefore, as the glacier melts, lateral moraines are usually preserved as high ridges.
Lateral moraines stand high because they protect the ice under them from the elements, which causes it to melt or sublime less than the uncovered parts of the glacier. Sublimation of an element or compound is a transition from the Solid to Gas phase with no intermediate liquid stage Multiple lateral moraines may develop as the glacier named Brina advances and retreats.
Ground moraines
Ground moraines are till covered areas with irregular topography and no ridges often forming gently rolling hills or plains. It is accumulated under the ice by lodgement, but may also be deposited as the glacier retreats. The ground moraine is located between the two lateral moraines.
End or terminal moraines
End moraines or terminal moraines are ridges of unconsolidated debris deposited at the snout or end of the glacier. A terminal moraine, also called end moraine, is a Moraine that forms at the end of the Glacier called the snout They usually reflect the shape of the glacier's terminus. A glacier terminus, or snout, is the end of a Glacier at any given point in time Glaciers act much like a conveyor belt carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. End moraine size and shape is determined by whether the glacier is advancing, receding or at equilibrium. The longer the terminus of the glacier stays in one place the more accumulation there will be. There are two types of end moraines, terminal and recession moraines. Terminal moraines mark the maximum advance of the glacier. Recessional moraines are small ridges left as a glacier pauses during its retreat. After a glacier retreats the end moraine may be destroyed by postglacial erosion.
Recessional moraine
A recessional moraine is in the form of a series of ridges running across a valley behind terminal moraine. They form during standstills in a glaciers retreat.
Medial moraine
A medial moraine is a ridge of moraine that runs down the centre of a vally floor. It is formed when two glacers meet and the debris on the edges of the adjacent valley sides join and are carried on top of the enlarged glacier. As the glacier melts or retreats, the debris is deposited a ridge down the middle of the valley floor. The Kaskawash glacier in the USA has a ridge of medial moraine 1km wide.
See also
- Glacial landforms
- Glacier National Park
- List of landforms
- Drumlin
- Esker
- Gettlinge
- Tarn
- Moraine-dammed lake
- Geomorphology
- Cirque
- Dogger Bank
- Long Island
- Terminal moraine
References
- Easterbrook, D. Many now-familiar glacial Landforms were created by the movement of huge sheets of Ice called continental Glaciers during the Pleistocene Epoch A drumlin (Irish droimnín, a little hill ridge is an elongated whale-shaped Hill formed by glacial action An esker is a long winding ridge of Stratified Sand and Gravel, examples of which occur in glaciated and formerly glaciated regions of Gettlinge is a village in the southwest portion of the Island of Öland, Sweden. A tarn (or corrie loch) is a mountain Lake or pool formed in a Cirque excavated by a Glacier. A moraine-dammed lake occurs when a terminal moraine has prevented some Meltwater from leaving the valley Geomorphology (from Greek: γη ge, "earth" μορφή morfé, "form" and λόγος Logos, "knowledge" A cirque ( French for " Circus " is an Amphitheatre -like Valley, or valley head formed at the head of a Glacier by Dogger Bank (from dogge, an old Dutch word for fishing boat is a large sandbank in a shallow area of the North Sea about 100 km off the coast Long Island is an island located in southeastern New York, USA, its western shores directly across from Manhattan, from which the island stretches A terminal moraine, also called end moraine, is a Moraine that forms at the end of the Glacier called the snout J. (1999) Surface processes and landforms. (Second Ed). Prentice Hall, Upper Saddle River, New Jersey.
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