The photo below shows that till is made of sedimentary materials of many different sizes.
Moraines are accumulations of till that have surface expression. A terminal moraine is a deposit that mark, the farthest advance of a glacier. Moraine deposits created during halts in the retreat of the glacier are called recessional moraines. The debris that falls from valley side slopes can be concentrated in a narrow belt and cause a deposit known as a lateral moraine. When two glaciers flow together, two lateral moraines can merge to form an interior belt of debris, called a medial moraine.
Till can be sculpted into drumlins. These are large mounds of glacial debris that have been shaped into features that are streamlined parallel to ice flow. Often, they have a rough tear-drop shape with the tail pointing in the direction of ice flow. Drumlins often form in groups or clusters. Drumlins come in a variety of dimensions. Lengths can range from 100 to 5000 meters and heights can sometimes exceed 200 meters.
The diagram below shows a plan and profile of a typical drumlin.
Erratics are another feature formed by till. Boulders are picked up and carried by ice, often for many kilometres, to be deposited in areas of completely different lithology. The large boulder in the picture below is a good example of an erratic.
Glaciofluvial deposits are generally quite stratified and less assorted in particle size. Outwash deposits are formed when sand is eroded, transported, and deposited by meltwater streams from the glacier's snout and nearby till deposits to areas in front of the glacier. Outwash plain develops when there are a great number of meltwater streams depositing material ahead of the glacier. Glaciofluvial deposits are also directly in front of the glacier. Where water rich in sediment flows off the snout of the ice, a conical-shaped pile of sediment, known as a kame, can be deposited. Many kames are often found on or at the edge of moraines.
Outwash plains are composed of gravels, sands and, uppermost and furthest from the snout, clays. They are deposited by meltwater streams issuing from the ice either during summer or when the glacier melts. The material may originally have been deposited by the glacier and later picked up, sorted and dropped by running water beyond the maximum extent of the ice sheets. Outwash material may also be deposited on top of till following the retreat of the ice.
Glaciers can also contain sinuous flows of meltwater that occur in ice tunnels at the base of the ice. The beds of these sub-surface glacial streams are composed of layers of sand and gravel. When the ice melts from around the meltwater tunnels, the beds of sand and gravel are deposited on the Earth's surface as long twisting ridges known as eskers. The slightly curving thin ridge in the centre of this photo is an esker located near Lac du Sauvage.
When glaciers retreat rapidly, numerous blocks of ice can become detached from the main body of the glacier. If glacial drift is then placed around the ice, a depression on the surface called a kettle hole can be created when the ice melts. Kettle holes are commonly found on moraine and outwash plain deposits. Large kettle holes that reach below the water table can form into lakes. The photo overleaf shows some kettle lakes in glacifluvial outwash complex located in the North-western District of Mackenzie. Some kettle holes develop into wetlands such as bogs, swamps, and marshes.
