Download
1 / 36
400 likes | 447 Views
12.0. Glaciation. 12.1. Glaciation. About two million years ago, the climates of countries such as Ireland became much colder. Some glaciers melted, while others joined together to form ice sheets. The ice sheets covered huge areas of the earth’s surface.
E N D
12.0 Glaciation
12.1 Glaciation About two million years ago, the climates of countries such as Ireland became much colder. Some glaciers melted, while others joined together to form ice sheets. The ice sheets covered huge areas of the earth’s surface. Snow turned to solid ice in upland areas. The ice moved to lowland areas under the influence of gravity as great rivers of ice called glaciers. Fox Glacier Attribution: ogwen
12.1 Glaciation During the last ice age, 14,000 years ago, almost one-third of the earth’s surface was covered in ice. Ice sheets of the last ice age
12.2 Erosion by Moving Ice As a glacier moves, it erodes the landscape by two main processes. 1. Plucking
12.2 Erosion by Moving Ice As a glacier moves, it erodes the landscape by two main processes. 2. Abrasion
12.2 Erosion by Moving Ice Features of Glacial Erosion
12.2 Erosion by Moving Ice Glaciated Valley AFTER BEFORE THE ICE AGE DURING A glaciated valley was originally a V-shaped river valley. It became straightened and deepened by a glacier filling it. This changed it to look more U-shaped.
12.2 Erosion by Moving Ice Cirques (Corries) Cirques – also called ‘corries’ – are found high up in the mountains. A cirque has three steep sides and may contain a lake. Waterton Park
12.2 Erosion by Moving Ice Cirques – Formation Snow collects in a mountain hollow high up in the mountain. With repeated snowfalls, the snow compacts to form ice. A glacier is born. 1
12.2 Erosion by Moving Ice Cirques – Formation Through plucking and abrasion, the hollow grows deeper. Freeze-thaw action is also at work here. 2
12.2 Erosion by Moving Ice Cirques – Formation When the glacier is big enough, it begins to flow over the edge of the cirque. It then begins its journey down the valley. 3
12.2 Erosion by Moving Ice Cirques – Formation 4 When the glacier melts, a lake called a tarn may be trapped in the cirque hollow.
12.2 Erosion by Moving Ice Cirques – Formation 5 When two cirques form back to back, the ridge between them is known as an arête.
12.3 Transport and Deposition by Moving Ice As a glacier moves, it transports eroded material. These materials are carried: underneath the glacier (subglacial transport). on the surface of the ice (supraglacial transport) within the ice (englacial transport)
12.3 Transport and Deposition by Moving Ice Features of Glacial Deposition and Meltwater
12.3 Transport and Deposition by Moving Ice Moraines A moraine is a mass of rocks and other material carried down and deposited by a glacier.
12.3 Transport and Deposition by Moving Ice Moraines Recessional moraine: 1 A moraine marking a temporary stop in the retreat (moving back) of a glacier.
12.3 Transport and Deposition by Moving Ice Moraines Lateral moraine: 2 Found at the side of the glacier, made of broken rock and soil that fell down the mountain and gathered at the side. This is supraglacial material.
12.3 Transport and Deposition by Moving Ice Moraines Terminal moraine: 3 Found at the front of the glacier, made up of material that is pushed ahead of the glacier. A terminal moraine marks the end point of the glacier.
12.3 Transport and Deposition by Moving Ice Moraines Medial moraine: 4 Found in the middle of a glacier when two glaciers combine. Their two lateral moraines join together. This is englacial material.
12.3 Transport and Deposition by Moving Ice Drumlins They often occur in large numbers known as swarms. Drumlins are oval-shaped hills that are made of deposited boulder clay.
12.3 Transport and Deposition by Moving Ice Drumlins – Formation 1 Glacial ice deposits boulder clay in irregular heaps.
12.3 Transport and Deposition by Moving Ice Drumlins – Formation The ice retreats and then advances again. This time it shapes and smooths the boulder clay into rounded oval-shaped hills. 2
12.3 Transport and Deposition by Moving Ice Drumlins – Formation The steep slope of the drumlin is the direction from which the ice advanced. The gentle is the direction in which the ice was travelling. 3
12.3 Transport and Deposition by Moving Ice Erratics Erratics are large boulders that were deposited by ice in an area where the rock type of the area is quite different to the rock type of the boulder. 8
12.3 Transport and Deposition by Moving Ice Eskers An esker is a long, winding ridge of sand or gravel. As the ice melts, large tunnels of meltwater flow in tunnels beneath the ice. 1 Esker
12.3 Transport and Deposition by Moving Ice Eskers An esker is a long, winding ridge of sand or gravel. When a river leaves an ice tunnel, it slows down and deposits material at the mouth of the tunnel. 2 Esker
12.3 Transport and Deposition by Moving Ice Eskers An esker is a long, winding ridge of sand or gravel. As the ice melts, the deposited material is dropped in a long, narrow ridge of sand and gravel. 3 Esker
12.3 Transport and Deposition by Moving Ice Outwash Plain An outwash plain is a flat area of sand and gravel, found in front of a terminal moraine.
12.3 Transport and Deposition by Moving Ice Outwash Plain – Formation As the ice sheet melts, huge amounts of meltwater flow out of it. 1
12.3 Transport and Deposition by Moving Ice Outwash Plain - Formation The water flushes large quantities of sand and gravel onto the lowland beyond the front of the ice. 2
12.3 Transport and Deposition by Moving Ice Outwash Plain - Formation As the meltwater loses energy, it deposits the heaviest material first, followed by the lighter material. 3
12.4 Glaciation and People Wicklow: Impact of Glaciation Glendalough is a glacial valley in Co. Wicklow. During the last ice age, the valley was carved out by the ice into the U-shape we see today. Glendalough valley Glendalough valley
12.4 Glaciation and People Wicklow: Impact of Glaciation Glaciation created steep topography and removed rich soil cover in upland areas. Forestry provides employment, both directly and indirectly, for many local people. Wicklow Mountains National Park attracts over one million visitors every year. Attractions include walking, fishing, flora and fauna. Glacial lakes provide natural reservoirs for the generation of hydroelectric power. Turlough Hill is the central control point for all hydroelectricity generation throughout Ireland.
