Transport and depositional landforms (Edexcel GCSE Geography A): Revision Notes

Transport and depositional landforms

What are transport and depositional landforms?

When glaciers move across the landscape, they pick up, carry, and eventually drop large amounts of rock material. This process of transport and deposition creates distinctive landforms that we can still see today in areas that were once covered by ice. These landforms work together with erosional processes to shape the dramatic landscapes we find in glaciated upland areas.

When the ice eventually melts or the glacier's carrying capacity is exceeded, this material gets deposited to form various types of ridges, hills, and other features across the landscape.

Moraines

Moraines are ridges or mounds of material that have been transported and deposited by glaciers. They form some of the most obvious evidence of past glacial activity and come in two main types.

Terminal moraines represent the furthest point that a glacier reached during its advance. These impressive ridges form at the snout (front end) of the glacier, where the ice stops advancing and begins to melt. As the glacier continues to flow forwards, it acts like a bulldozer, pushing material ahead of it and piling up enormous quantities of rock debris. This creates substantial ridges that can be several metres high and stretch across entire valleys.

Ground moraines form as glaciers retreat and melt across the landscape. As the ice melts, it drops all the material it was carrying - a mixture called boulder clay or till. This material gets spread across the valley floor in an uneven, hummocky pattern. Ground moraines create the rolling, bumpy terrain characteristic of many formerly glaciated areas, with small hills and hollows scattered across the landscape.

Drumlins

Drumlins are distinctive elongated hills that look remarkably like giant eggs when viewed from above. These landforms develop beneath advancing glaciers and provide excellent evidence of the direction ice was flowing.

The formation process begins when a glacier encounters an obstacle on the valley floor, such as a large boulder or outcrop of resistant rock. As the ice flows around this obstacle, it deposits glacial material in a streamlined shape. The stoss end of the drumlin is the blunt, steeper side that faced the direction from which the ice was flowing. The lee end is the longer, more gently sloping side that points in the direction the ice was moving.

They rarely occur alone - instead, they form in groups called swarms or, more colourfully, "baskets of eggs" due to their appearance on maps and from aerial views.

Crag and tail

Crag and tail landforms demonstrate how glaciers interact with particularly resistant outcrops of rock. These features consist of two distinct parts that tell the story of glacial erosion and deposition working side by side.

The crag is a steep-sided rocky hill made of hard, resistant rock that the glacier could not easily erode. As the ice encountered this obstacle, it was forced to flow up and over it, causing significant erosion on the upstream side where the glacier had most power.

The tail is a gently sloping ridge of deposited material that extends away from the crag in the direction of ice flow. This ridge forms because the resistant rock created a "shadow zone" behind it where the glacier had less erosive power. Instead of eroding material away, the ice deposited debris in this sheltered area, gradually building up the characteristic tapering ridge.