Weathering, Erosion and Distinctive Landscapes

1. Weathering, Erosion and Distinctive Landscapes Explain the terms weathering and erosion. Name and describe the process of chemical and mechanical weathering Describe and draw a limestone pavement Describe surface and underground landforms of a karst landscape Understand how this topic appears on the exam papers.

2. Mind Map: Weathering • Lets do a mind map to remember what you learn from junior cert geography

3. Key words • Denudation • Mechanical weathering • Chemical weathering • Biological weathering

4. Denudation This is all processes involved in the shaping of the earths crust Denudation = weathering and erosion

5. Weathering • Weathering is the breaking down and decay of rocks that are exposed to the weather • There are three types • Mechanical – Frost and temperature changes • Chemical – Rocks are dissolved • Biological – Plants and animals

6. Erosion • Erosion is the breaking down and removal of the rock. • Three types of erosion • Moving water (rivers and sea) • Moving ice (Glaciation) • Moving air (wind)

7. Mechanical Weathering • 3 Types • Freeze Thaw Action • Exfoliation • Crystallisation of salts – When salts in a rock grow they can split the rock apart.

8. Mechanical WeatheringFreeze Thaw Action • Weathering by frost is called freeze thaw action

9. In order for freeze thaw action to occur you need to have… • Temperatures that rise above and fall below freezing (0°C) • A good supply of water from rain, snow, sleet or hail.

10. Freeze Thaw Action • http://www.absorblearning.com/media/attachment.action?quick=131&att=2799 • Where do you think this action usually occurs???

11. Mechanical Weathering - Exfoliation • ‘Onion Peeling’ • Major contrasts in temperature • Rises very high during the day and drop very low at night • The change in temperature expands and contracts the rock causing the outer skin to shatter.

12. Class Activity • Summarise the three types of mechanical weathering into your copies.

13. Biological Weathering • Action of plants, animals and man can speed up mechanical and chemical weathering

14. Chemical Weathering Keywords • Carbonation • Oxidation • Hydration • Hydrolysis

15. Chemical Weathering • Four types of chemical weathering • Carbonation • Oxidation • Hydration • Hydrolysis Research the types of chemical weathering.. Teach the class.

16. Distinctive Landscape • Granite Landscape • Limestone Pavement – Karst Landscape. Burren Co. Clare

17. Karst Keywords • Burren • Tower Karst Landscape • Carbonation • Calcium Carbonate • Calcite • Limestone Pavement • Swallow Hole • Cavern • Dripstone Formations

18. Karst Region • These are bare limestone regions • Ireland’s best known Karst region the Burren in Co. Clare • Burren = Rocky place (An Boireann) • Soil in the area removed by Erosion • International Example – Tower Karst Landscapes

19. The Burren

20. Surface and Underground Landforms • Surface Limestone Pavements Swallow holes • Underground Caverns Dripstone formations

21. The Burren

22. Limestone Pavement Examples • Near Black Head in the Burren Co. Clare • Marble Arch Uplands in Co. Fermanagh

23. Revision… Limestone • In your groups do a limestone revision mindmap… • Remember the characteristics of limestone!!

24. Limestone Pavement Formation • Limestone pavements from from the process of carbonation ‘All the Cs!’ • Carbon dioxide in the air + rain = Weak Carbonic Acid. • Lands on limestone rock creating a chemical reaction. • Hydrogen in the carbonic acid separates the calcium carbonate (limestone) into calcium and bicarbonate atoms • These are soluble and are washed away… as a result the limestone is dissolved.

25. Limestone Pavement • An exposed area of limestone • Limestone is permeable. When rainwater falls onto the surface of the limestone it moves underground through joints and cracks in the rock. • It has grikes and clints

26. A Limestone Pavement is just like a bar of dairymilk chocolate!! • Each group will be given a bar of chocolate…. I’d like you to describe the physical features of the bar of chocolate… • DO NOT EAT IT!! WE NEED IT FOR THE REST OF THE CLASS!!

27. Clints • These are the top flat pieces of the limestone. • These are formed by chemical weathering dissolving away some of the rock landscape.

28. Clints

29. Grikes • These are the joints or cracks between the Clints • These have been formed by chemical weathering. • Carbonic acid (acid rain) expands the width and depth of the cracks

30. Grikes

31. Class Activity • Read page 59 of your book. Exam Question Describe the formation of any one rock type and how it produces a distinctive landscape. • Describe the formation of limestone… notes from rock chaper • Describe formation of a karst landscape and limestone pavements • Use two examples Burren Co. Clare and Tower Karst Landscape (page 63)

32. Sinkholes/Swallow holes An opening in the bed of the river through which a river disappears underground in a limestone region

33. Swallow Hole Bedding Plane Grikes

34. Class Activity: Sinkholes • Read the formation of a sinkhole on page 60 of your book. • Summarise the landforms in grouop

35. CAVE

36. Cavern

37. Animation of a Cavern • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1405/es1405page01.cfm

38. Activity: Read page 61 • Write out caverns into your own words into your copies

39. Dripstone formations • Include stalactites, stalagmites, pillars, columns and curtains. • Formed from the mineral calcite. Calcium carbonate in its purest form. • Read page 62 in your book. Summarise into your own words.

40. Stalagmites • When the drops of water fall to the floor and evaporate, they also deposit calcite. These deposits build up in a conical shape to form Stalagmites

41. Stalagmites

42. Stalactites • When water containing dissolved calcium carbonate seeps through the rock, some drops hang from the roof of the cave/cavern for a while. Some of the water evaporates leaving behind deposits of calcite. These deposits build up over thousands of years and hang from the roof to form Stalactites.

43. Stalactites

44. Pillar • In time, the Stalactites and Stalagmites grow and join up to form pillars.

45. Pillar

46. Exam Questions: Could be asked for Underground or Surface Landforms • Prepare questions to suit both surface and underground.

47. Weathering, Erosion and Distinctive Landscapes Explain the terms weathering and erosion. Name and describe the process of chemical and mechanical weathering Describe and draw a limestone pavement Describe surface and underground landforms of a karst landscape Understand how this topic appears on the exam papers.