Which landforms result from moving or melting ice?

When a glacier loses the ability to transport material, depositional landforms are formed. As the ice melts, the material it is transporting is deposited on the ground. As a glacier moves, material being transported in its base that has been plucked from the bedrock can be dropped. This could be because it gets stuck behind obstacles on the floor, such as a band of hard rock. Most of the material that is deposited is till. Where ice has melted and retreated, we see drumlins and moraines.

Glacial moraine

What are the different types of moraine?

Moraines are piles of rock debris. There are several types of moraine, each with its own shape. These are:

• Lateral moraine – lateral means towards the sides. A lateral moraine is a material ridge found along a U-shaped valley’s edge. This material results from freeze-thaw weathering along the sides of the valley. Frost-shattered rock falls onto the glacier, and the material is deposited on the valley floor as the ice melts.
• Medial moraine – medial means in the middle. When two glaciers meet side-by-side, the lateral moraines join to form a ridge of rock. These are visible as a dark line running down the centre of the merged glacier. When the ice melts, the material is deposited in the centre of a U-shaped valley.
• Ground moraine – material is frozen to the glacier’s base and gets stuck and deposited on the valley floor is known as ground moraine. Large areas of the UK were covered in ground moraine at the end of the last ice age.
• Terminal moraine – terminal means end. As its name suggests, this material is found at the glacier’s end or snout. It is material that the glacier has bulldozed. It is usually a large ridge of material indicating the distance a glacier has travelled.

What are the different types of glacial moraine?

Drumlins

The main features of a drumlin

A drumlin is an egg-shaped formation made up of till. They are formed when material is deposited as ground moraine. This is then shaped by the movement of the ice. Drumlins show the direction of ice movement. They can be 100 metres long or more. A group of drumlins is known as a basket of eggs. Some drumlins have a large piece of rock in their centre.

What do ‘glacial erratics’ tell us about past ice movements?

An erratic is a rock or boulder that differs from the surrounding rock and has been transported by ice over a long distance and deposited by a melting glacier. They provide evidence of the route a glacier has taken.