EROSIONAL PROCESSES

1. EROSIONAL PROCESSES T Parson – Allerton Grange

2. Abrasion Abrasion is scraping of a rock surface by friction between rocks and moving particles during their transport in wind, glacier, waves, gravity or running water – essentially a sandpapering action. The intensity of abrasion depends on the hardness, concentration, velocity and mass of moving particles. http://www.uky.edu/AS/Geology/howell/goodies/elearning/module07swf.swf Find abrasion by clicking NEXT

3. Task : Abrasion The glacier moves slowly across the landscape Using a flow diagram (text or diagrams) describe and explain the process of plucking ? ? Use as many boxes as you need, remember the more detail the better !

4. Plucking Plucking, in the sense relating to glaciers, is when a glacier erodes away chunks of bedrock to be later deposited. Glacial plucking exploits pre-existing weaknesses in the bedrock. When the ice comes into contact with a joint, the friction on the ice results in melting of some of the ice. The ice then refreezes within the rock fracture. This is then followed by the entrainment of the loosened rock by the ice. The glacier moves ‘plucking’ the loosened material. Plucking is also known as quarrying. http://www.geocities.com/CapeCanaveral/7639/land/pluckng.htm

5. Task : Plucking There are faults, cracks or areas of weakness in the rock Using a flow diagram (text or diagrams) describe and explain the process of plucking ? ? Use as many boxes as you need, remember the more detail the better !

6. Freeze-thaw action This process can also be called frost shattering. Common in areas where the climate fluctuates around freezing point. Moist soils expand or frost heave upon freezing as a result of water migrating along from unfrozen areas via thin films to collect at growing ice lenses. Pore spaces expand as liquid is attracted from surrounding pores. This pressure is exaggerated with the process of freezing/thawing, putting pressure on the surrounding rocks. http://www.uky.edu/AS/Geology/howell/goodies/elearning/module07swf.swf Find freeze-thaw by clicking NEXT

7. Freeze-thaw action continued… Freeze induced weathering action occurs mainly in environments where there is a lot of moisture, and temperatures frequently fluctuate above and below freezing point—that is, mainly alpine and periglacial areas. An example of rocks susceptible to frost action is chalk, which has many pore spaces for the growth of ice crystals. This process can be seen in Dartmoor where it results in the formation of tors. The splitting of rocks along the joints into blocks is called block disintegration. The blocks of rocks that are detached are of various shapes depending on rock structure.

8. http://youtube.com/watch?v=PMDXJlC-c-w&feature=related http://www.geography.ndo.co.uk/animationsweathering.htm# http://www.bbc.co.uk/schools/gcsebitesize/geography/glaciation/glacialprocessesrev2.shtml

9. Task : Freeze – thaw weathering Using 4 diagrams describe and explain freeze – thaw weathering A rock fills with water as the climate is moist, the temperature is above freezing.

10. Nivation Nivation is the process of alternative freeze and thaw by which fallen snow gets converted into ice or Névé. When the neve is large enough to move it becomes a glacier. Other erosion processes may occur beneath the snowpatch.

11. Task : Nivation Describe nivation in three sentences

12. Slide 2/4 – drawing needs re-doing http://www.flickr.com/photos/deego/1091977848/ - Slide 6/7 picture http://www.flickr.com/photos/dougmcneall/2512553556/ - Slide 8 picture http://www.flickr.com/photos/davejglaves/1103055883/ - Slide 8 picture http://www.flickr.com/photos/35127493@N00/114072481/ - Slide 10 picture