Fluvioglacial landform

These streams under immense pressure and at high velocities along with the overlying weight of the glacier itself are able to carve into landscapes and pluck sediment from the ground.

[7] The two processes of advancement and retreat have the power to transform a landscape and leave behind a series of landforms that give great insight into past glacial presence and behavior.

Landforms that result from these processes include moraines, kames, kettles, eskers, drumlins, plains, and proglacial lakes.

Glaciofluvial deposits or Glacio-fluvial sediments consist of boulders, gravel, sand, silt and clay from ice sheets or glaciers.

[8] Low, straight ridges as much as 10 metres (33 ft) high may be formed where sediment fills in crevasses within the glacier or at its base.

[8] A kame is a short mound or ridge with steep sides of sands and gravels deposited from melted ice.

[9] Kame terraces are benches of sand and gravel that were deposited by braided rivers flowing between the side of the valley and the glacier's ice margin.

[13] The turbulent and fast-moving meltwater streams cause mechanical erosion through hydraulic action, cavitation and abrasion.

[11] The channel of the braided streams are very unstable due to high loads of sediment, fluctuations in discharge and lack of plants to anchor the banks.

[17] The amount of material deposited is generally greatest near the end of the glacier, so the sediment will tend to slope down and thin out from that point.

[17] Terraces are formed when the streams grade down to lower levels and abandon higher and older outwash plains.

[12] The sediment is deposited in bedforms ranging in scale from sand ripples a few centimeters across to gravel bars several hundred meters long.

[17] Glaciofluvial streams dominated by annual ice melting events may merge into a normal fluvial environment where non-glacial inflows are more important.

[16] Deposits from the subsiding waters of an outburst flood may be poorly sorted, with a wide range of grain sizes, and without distinct bedforms.

[21] Both original and reworked moraines record a continuum of processes occurring on the landscape as a result of glacial presence.

Medial moraines may also form as subglacial and englacial material is carried upward by ice flow and collects at the surface and inside the glacial body.

Ground moraines are regions of glacial till that form relatively flat areas or gently rolling hills.

Instead, glacial meltwater is diverted laterally along the ice margin and deposits sediments between the glacier and valley wall.

[30] Exact kame terrace morphology is dependent on the flow of the formative meltwater stream, and the angle between the ice margin and valley wall.

A kame delta is a flat-topped landform of well sorted sand and gravel glaciofluvial sediments deposited by a meltwater stream into a body of water or river system.

[4] The height and width of an esker are determined by the water and ice pressure and sediment load at the time of formation.

Under less pressure, often near the terminal end of a glacier, where the ice moves rather slowly, steeped walled eskers may form.

A collection of drumlins in one area is referred to as a field or swarm and creates a landscape sometimes called a “basket of eggs topography”.

[38] The first, often called constructional, suggests that glacial till is deposited by meltwater streams and accumulated by the continual push of an overlying glacier.

[39] The second theory is that the erosion caused by the heavy overlying glacier scrapes material from an unconsolidated sediment bed and repositions it and deposits it at the drumlin.

In all circumstances, because the subglacial region is not visible until after the glacier has retreated and because there is great variability in drumlin presentation, there remains some uncertainty as to the processes that shape these landforms.

[41] Outwash plains may contain other glaciofluvial landforms including meltwater streams, kames, and kettle lakes.

The composition of a till plain varies greatly and is dependent upon the path the glacier took and the bedrock underlying the glaciated region.

[26] Till plains are composed of poorly sorted sediment ranging in size from sand to large boulders.

The sediment contained in a proglacial lake is a useful geochronological tool that records patterns of change in a glaciated region.