study of ice and its impact on the environment.
The Ice Age in Britain lasted from about one million years ago to
about 20 000 years ago. During that time the Northern and Eastern
parts of the British Isles were covered in ice. Glaciers were formed
which move down valleys with great erosive power. These glaciers
carved new scenery. How
form and flow?
are three main types of glacial
erosion - plucking, abrasion and freeze thaw.
is when meltwater from a glacier freezes around lumps of cracked
and broken rock. When the ice moves downhill, rock is plucked
from the back wall. Abrasion is when rock frozen to the base and
the back of the glacier scrapes the bed rock. Freeze-thaw is when
meltwater or rain gets into cracks in the bed rock, usually the
backwall. At night the water freezes, expands and causes the crack
to get larger. Eventually the rock will break away.
Landforms - Upland Features
- This is an arm chair shaped hollow found in the side of a mountain,
- This is a narrow, knife edge ridge separating two corries, e.g.
Striding Edge, Helvellyn.
Peaks - These are formed when three or more corries form in the
side of one mountain, e.g. The
Matterhorn, Austria or Mount Snowdon,
Snowdonia National Park, Wales
Tarn - This is a lake found in a corrie, e.g. Red Tarn, The Lake
Landforms - Lowland Features
glacial features include:
U-shaped Valley - This a valley which was V-shaped but has been
eroded by ice. The valley sides are steeper and the valley floor
flatter after the ice melts. Hence the name U-shaped valleys.
Truncated Spurs - These are spurs which have been cut through
by ice, e.g. Nant Francon Valley, Snowdonia.
Hanging Valleys - These occur when glaciers at higher levels than
the main valley didn't experience such powerful erosion. Tributary
streams enter the valley as waterfalls from hanging valleys.
Ribbon Lakes - These are lakes found in U-shaped valleys, e.g.
Lake Windermere, Lake District.
- These are hills shaped like eggs! (see diagram below)
are blunt at one end and tapered at the other. Drumlins are found
in swarms called 'basket of eggs'
topography. This is because they look like eggs in a basket! They
are formed when ice is moving forward, but is also melting. The
ice deposits boulder clay and till when it comes across a small
obstacle (e.g. small rock outcrop). Most material is deposition
the 'up stream' end of the drumlin. The down stream end is shaped
by the ice.
Study - Helvellyn, Lake District
following links are to web sites containing case study information
about Helvellyn, an area containing glaciated landforms in the
Lake District, England.
360° 3D view of Helvellyn
glaciers - Helvellyn - A great case study of a corrie
glacier in the UK. Ideal for GCSE