Glaciers

Theories of Glaciations Volcanic Eruptions Volcanic eruptions send a layer of ash And dust into the Earths atmosphere Which blocks out the Suns solar radiation, resulting in cooling. Reduced CO2 When the amount of CO2 is reduced this lowers the Earths ability to absorb radiation, so less heat is trapped in the atmosphere. Earths Axis Changes in the Earths axis or orbit may cause the absorption of solar radiation to lower

Alpine and Continental Glaciation Alpine glaciation takes place on fold mountains that are close to coastlines, causing them to be exposed to onshore winds. Due to the frequent freezing and thawing, the head of the glacier often plucks out the side of the mountain. A circular amphitheater is cut into the peak. This is also known as a “cirque”. A well-known example of this would be Mt. Kilimanjaro. Continential Continental glaciation covers continental land masses, for example: Greenland. While alpine glaciation only covers mountain tops, continential glaciation covers land masses that are closer to the poles, regardless of elevation.

Eroding and Depositional Terms Plucking Plucking is a result of when glacial meltwater runs into rocks cracks and refreezes causing chunks of rock to attach to the glacier. When the glacier moves, the rock that is attached is ripped off and carried away. This process often results in surfaces such as the one below. Till Unsorted and unstratified glacial debris. Example: Sand, gravel, boulders Abrasion When debris and rock that is attached to the glacier gouges, scapres and polishes the rock surface that it is sliding over, leaving the surface smooth like the picture below. Outwash Deposit left from meltwaters. Water transports this debris and causes it to be sorted and stratified. The heaviest materials are deposited first. Drift Any material that has been deposited by a glacier.

Alpine Landscapes (Erosional) Hanging Valleys Smaller u-shaped troughs that join the main valley ay right angles. Horn The remaining rock pinnacle when a cirque connects around a peak. Tarn Remaining mountain lake after a cirque. Cirque Armchair like depression Arete Sharp, knife-edged ridges of a rock between cirques Truncated Spur Triangular faces of vertical walls of the U-shaped valley. Crevasses Cracks that occur when glaciers move into a wider part of the valley or encounters a change in the slope. Striations Glacial scratches on exposed rock Fjord Drowning of a U-Shaped valley by the sea.

Alpine Landscapes (Depositional) Ground Moraine The layer of til that covers the underlying bedrock. Lateral Moraine Erosional debris left at the side of the valley. Recessional Moraine Located at the higher elevations. Forms as glaciers pause during periods of retreat. Terminal Moraine Marks the farthest extent of glacial advance and thus is the end of the moraine located at the lowest elevation. Medial Moraine When the lateral moraine of two glaciers combines to form a single line.

Continential Landscapes (Erosional) Striations Scratches on rock strata Glacial Erratics Isolated boulder left by a glacier Roche Moutonnee Smooth mound of bedrock caused by glacial abrasion Kettle lakes Formed by melting of stagnant block of ice

Continential Landscapes (Depositional) Outwash Plain Deposition of sediment in front of glaciers formed and carried by meltwater. Drumlins Tear-shaped hills where the steep end faces the direction in which the ice came. Eskers Ridges of sand and gravel; deposited by subglacial streams

5 Benefits of Glaciation Melting glaciers resulted in many rivers and lakes, providing a water source for hydroelectric power. Moving glaciers stripped the Canadian Shiel of soil, exposing the underlying bedrock and it’s valuable minerals. Glaciers deposited valuable and fertile soils into the Prairies Glaciers are tourist attractions. Example: Skiing on glaciers Provides freshwater for humans and surrounding flora and fauna

5 Disadvantages of Glaciation Although exposure of bedrock may be useful, this involves the removal of fertile soil that was originally covering the rock. Living in a glaciated region may result in floods during warmer seasons. Glaciers often lay down poor quality soil if they don’t strip it away. Poor soil left behind is only good for growing vegetation of little value. Glacial boulder clay is subject to erosion at coastlines, resulting in loss of settlements alone the shorelines.