A glacier is a huge mass of ice that moves slowly over land. Alpine glaciers are also called valley glaciers or mountain glaciers. Ice sheets, unlike alpine glaciers, are not limited to mountainous areas. They form broad domes and spread out from their centers in all directions.

The front of a glacier is known as the terminus.

A warm-based glacier or ice sheet will have liquid water at its base. Water and ice together are highly erosive, and the combination often scours landscapes. A cold-based ice sheet, however, will simply freeze to the bed, preserving whatever lies under the ice, even as the upper layers of ice flow over it.

The classic drumlin shapes is a hill that highest on its up-glacier end and tapers gently from there, like a half-buried egg. Because they have been streamlined by flowing ice, scientists often use them to understand past glacier flow directions. They are longest in the direction of flow.

Valley glaciers form several unique features through erosion, including cirques, arêtes, and horns. Glaciers deposit their sediment when they melt. Landforms deposited by glaciers include drumlins, kettle lakes, and eskers.

Drumlins are generally found in broad lowland regions, with their long axes roughly parallel to the path of glacial flow. Although they come in a variety of shapes, the glacier side is always high and steep, while the lee side is smooth and tapers gently in the direction of ice movement.

Drumlins are oval-shaped hills, largely composed of glacial drift, formed beneath a glacier or ice sheet and aligned in the direction of ice flow.

What is an esker? Eskers are ridges made of sands and gravels, deposited by glacial meltwater flowing through tunnels within and underneath glaciers, or through meltwater channels on top of glaciers. Over time, the channel or tunnel gets filled up with sediments.

Two types of drift are Till (unsorted, unstratified debris deposited directly from ice) and Stratified Drift (sorted and stratified debris deposited from glacial meltwater). The front edge of the glacier remains stationary while the conveyor belt of ice brings down more material.

A large amount of snow that stays around all year is called a snowfield. If they grow large enough, the snow will pack together into ice and begin to flow like a glacier. A glacier is a large amount of ice that sits on the land.

Eskers were formed by deposition of gravel and sand in subsurface river tunnels in or under the glacier. The ice that formed the sides and roof of the tunnel subsequently disappears, leaving behind sand and gravel deposits in ridges with long and sinuous shapes.

Subglacial meltwater channels can form networks, similar to those that form on ground today. Flow is driven by pressure gradients as well as elevation, so these channels can flow uphill and therefore have undulating long profiles1, that go up and down.

Notable areas of eskers are found in Maine, U.S.; Canada; Ireland; and Sweden. Because of ease of access, esker deposits often are quarried for their sand and gravel for construction purposes.

An esker is a sinuous low ridge composed of sand and gravel which formed by deposition from meltwaters running through a channelway beneath glacial ice.

An esker, eskar, eschar, or os, sometimes called an asar, osar, or serpent kame, is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North America.

A horn results when glaciers erode three or more arêtes, usually forming a sharp-edged peak. Cirques are concave, circular basins carved by the base of a glacier as it erodes the landscape. The Matterhorn in Switzerland is a horn carved away by glacial erosion.

The largest glacier in the world is the Lambert-Fisher Glacier in Antarctica. At 400 kilometers (250 miles) long, and up to 100 kilometers (60 miles) wide, this ice stream alone drains about 8 percent of the Antarctic Ice Sheet. Antarctic ice is up to 4.7 kilometers (3 miles) thick in some areas.

At a terminal moraine, all the debris that was scooped up and pushed to the front of the glacier is deposited as a large clump of rocks, soil, and sediment. Scientists study terminal moraines to see where the glacier flowed and how quickly it moved.

Moraines may be composed of debris ranging in size from silt-sized glacial flour to large boulders. The debris is typically sub-angular to rounded in shape. Moraines may be on the glacier’s surface or deposited as piles or sheets of debris where the glacier has melted.

A terminal, or end, moraine consists of a ridgelike accumulation of glacial debris pushed forward by the leading glacial snout and dumped at the outermost edge of any given ice advance. It curves convexly down the valley and may extend up the sides as lateral moraines.