What is a Moraine?

The moraine is a feature of the landscape. It's a ridge of soil and rocks, with a depression on top. The ice pushes boulders up onto the sides of the glacier as it moves forward. When the glacier melts away, the material from the sides gets dumped in a ridge of debris. It forms from debris that the receding glacier has deposited. Eventually, the moraine is worn back into the soil through weathering.

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Types of Moraine

There are mainly four types of the moraine, namely- medial moraines, supraglacial moraines, lateral moraines, and terminal moraines.

Lateral ones are typically found on the sides of glaciers. They occur as the ice sheet retreats and generates piles of debris, or they form as a glacier pushes against a large existing rock formation. Medial one forms as two lateral moraines from opposite sides of a glacier merge with one another. Supraglacial moraines occur when the glacier is in direct contact with a permanent body of water, such as a lake or ocean. Finally, terminal moraines form at the end of a glacier furthest from its source, where the ice is thickest and can spread out to cover an area thousands of miles rather than just melting in place.

Moraines of the last glaciation became significantly more complex and widespread than they did during previous glaciations. During the Quaternary Period, cryoplanation was responsible for the formation of many of the larger, more complex moraines that we see today. As climate change occurs, these moraines will continue to move and shift, which will create new landforms and new formations.

Glacial Moraines

They are the rocky debris found at the end of glaciers, also forming bodies of rock called rock glaciers. Rock glaciers are not perfectly hard solid ice, despite one sometimes thinking that it may be so. They are, in fact, masses of stone covered in ice, but in some cases, the ice is in the solid-state with no water in evidence, and in other cases, there is indeed water trapped in crevices in the rocks.

Terminal Moraine

The terminal moraine is a glacier system deposited at the end of a glacier. It is deposited when the glacier comes to a halt, and the ice that was pushing against the rock in front of it melts back, exposing it. They are often found in association with Roche moutonnées and drumlins. It is basically a feature caused by long-standing and fast-flowing glaciers and occurs at the snout of some glaciers.

Lateral Moraines

They are formed when a large mass of ice is stopped in its movement. This can be triggered by a large boulder that stops the flow of the ice, or it may be caused by a sudden drop in the bed of the glacier. Apart from its formation, you will find many interesting facts pertaining to its effects. It is a ridge of glacial debris formed by a glacier when it flows in a confined space or when the pressure from the expanding ice front forces the sides of the glacier outward to form an offshoot. It is one of five types of moraines.

It is a type of moraine that forms along the sides of glaciers rather than at the front. The same processes create them as medial ones (the pointy bits on either side of a valley), but they form further down the valley because the glacier has flowed along the side of it rather than up it.

Ground Moraine

It is found in areas where there are glaciers. As the glacier moves, it pushes rocks in front of it. When the glacier melts, you will find rocky deposits left behind by the ice age. These rocky deposits are called ground moraines.

We can distinguish two types of the ground moraine, like frozen soil (retro-moraines) and flat-lying till plains (recessional moraines). The latter is further subdivided into solifluction or earthflow deposits, where soil materials have flowed under the influence of percolating groundwater, and ice-flow deposits, which are formed by the sliding of surface soil down firn slopes.

Ground moraine is an accumulation of material in an ice-contact zone on land, where the ice is flowing away from the shoreline. It is located below and behind a moving glacier and can be found just offshore underwater and at the terminal and recessional moraines associated with the glacier's snout. The word moraine comes from the French language and refers to any glacial debris, both of which accumulate at the base of advancing glaciers as well as along their sides.

Medial Moraine

It is a ridge that appears between two tributaries of an active glacier. Formed by the glacier's bulk, the moraine may also be called a medial moraine ridge or medial moraine wall. They are distinct from the end or lateral moraines. Although they are composed of debris derived from the same source, they are deposited along the sides of the glacier rather than at its end.

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FAQs (Frequently Asked Questions)

1. State some facts about moraines.

Two facts about moraines are as follows.

  • It is a ridge of debris dumped in a line across a glacier's path. The ridged form becomes visible when the glacier recedes, exposing the moraine to view.

  • Medial one, unlike lateral and end moraines, is deposited in the middle of a glacier. They form when two lateral from opposite sides of a valley converge.

2. How are glacial moraines formed?

They are a pretty amazing phenomenon. They're a feature that exists in a lot of places, for example, in the Alps of Europe. But they only form in colder climates. The same forces that move glacier ice also build up these long ridges of gravel and stone. They last after the glaciers have retreated, increasing the land height and contributing to erosion. They are landforms created by the deposition of material produced by a glacier. As ice flows over the Earth's surface, it picks up rocks, soil, loose materials, and everything else lying on top of the glacier. This debris is ground into smaller pieces by the motion of the ice and then dumped in mounds at the end of the glacier, where they are left after it melts.