1 / 29

Karst Landscapes

Karst Landscapes. AS Geography. Learning Outcome. Understand the processes involved in the formation of Karst Landscapes. List examples of Karst regions. Describe the surface and underground landforms in a Karst region. Explain the life cycle of a Karst landscape. Karst topography

Download Presentation

Karst Landscapes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Karst Landscapes AS Geography

  2. Learning Outcome • Understand the processes involved in the formation of Karst Landscapes. • List examples of Karst regions. • Describe the surface and underground landforms in a Karst region. • Explain the life cycle of a Karst landscape.

  3. Karst topography • Exposed limestone • Landscape created by water • Dissolving of carbonate rock

  4. Examples of Karst Regions The Burren, Co Clare Marble Arch, Co Fermanagh Kras, South-West Slovenia Guilin, Guangxi Region, China

  5. Limestone & Carbonation • Limestone is permeable • Rain takes in carbon dioxide as it passes through the atmosphere • Carbon dioxide (CO2) dissolves in rainwater (H2O) • Forms weak carbonic acid (H2CO3) • The carbonic acid reacts with the calcium carbonate (CaCO3) in the limestone • This forms calcium bicarbonate (Ca(HCO3)2), which is soluble in water • This solution percolates through rock • It removes the calcium carbonate • Fissures in rock become enlarged • Underground drainage system develops

  6. Karst Landscapes Surface Landforms

  7. Limestone pavement • Exposed area of limestone • Rugged and bare landscape with flat areas of rock surface

  8. Formation of a Limestone Pavement • Carbonation (chemical weathering) • Rainwater mixes with carbon dioxide in the air • Forms a weak carbonic acid • More carbon dioxide is absorbed when the water percolates through the soil • Solution; water containing the carbonic acid dissolves the permeable limestone • Joints and cracks (i.e. bedding) are widened by this process • e.g. the Burren, Co Clare

  9. Features of limestone pavements • Clint: section of a limestone pavement separated from adjacent sections by grikes • Grike: vertical fissure that develops along a joint in limestone • Karren: small hollow that forms on the surface of a limestone clint

  10. Swallow Holes • A river disappears underground in a limestone region

  11. Formation of Swallow Holes • River reaches an area of permeable rock • Disappears down through grikes • Grikes made bigger by solution (carbonation) • Forms swallow hole (sinkholes)

  12. 2. Dry valley = remains of river valley downstream from sinkhole River of resurgence = where river reappears at the surface

  13. Pairwork Quick Questions • Explain the process of carbonation. • Explain the term ‘permeable’. • Name two surface landforms in a limestone region. • Which part of the limestone pavement would you walk on? • Give two other words used to describe a swallow hole.

  14. Learning Outcome • Lesson 2 • Recap on Karst landscapes & examples • Recall the surface landforms in a Karst region • Complete & Label diagram showing all Karst features • Watch video clips explaining the formation of Karst landforms • Homework; Page 84 Q 1, 2 & 3.

  15. Karst Landscapes Video Clips

  16. Karst Landscape Underground Landforms

  17. Caves • Swallow holes – river disappears underground • Carbonation – passages form large caverns • River erodes the rock of the cave by abrasion and hydraulic action • Carbonation and solution dissolve permeable rock (limestone) • Cave develops at or below zone of saturation • e.g. Ailwee Cave, the Burren, Co. Clare; Dunmore caves,Kilkenny

  18. Dripstone Features Stalactites • Drops of water containing dissolved limestone seep down through cracks/fissures in the cave roof • Drops of water lose carbon dioxide and deposit calcite • Over time deposition of calcite forms the stalactites hanging down from the roof of the cave • Stalactites are hollow mineral tubes, like drinking straws • They are very thin and fragile Stalagmites • Water droplets fall to the cave floor • Drops of water lose carbon dioxide and deposit calcite • Over time deposition of calcite form the stalagmites growing upward from the cave floor form directly below stalactites • Stalagmites are thicker than the stalactites

  19. Pillars • Stalactites and stalagmites grow towards each other • Eventually join to form a pillar or column Curtains • Rainwater drips from a long crack in a cave roof forms a continuous strip of calcite

  20. The Burren, Co. Clare • Covers approximately 250 square km of north-west Clare • Formed during the carboniferous period, 355 to 290 million years ago • Formed of limestone rock Features include: • Limestone pavements • Subsurface and dripstone features • e.g. Ailwee Cave

  21. Pairwork; OS Map Task • OS Map of the Burren Area, page 82 • Give a grid reference for the Ailwee area • Identify the height of the limestone terrace shown on the map • Locate and identify two swallow holes found on this OS map extract

  22. Cycle of Erosion in a Karst Topography • Three stages: • Youthful • Mature • Old age

  23. Youthful stage • Rivers flowing on the surface • Erosion of impermeable rock • Then erosion of permeable rock (limestone) • Chemical weathering (carbonation) • Formation of swallow holes

  24. Mature stage • Dry valleys on the surface • Swallow holes

  25. Old age stage • Weathering • Removal of limestone • Older more resistant rock left prominent – hums • Rivers once again flow over the surface

  26. Quick Revision Questions • Name the main weathering process effective on limestone • List the three parts of a limestone pavement • Name another surface landform found in a limestone region • Name four underground landforms in a limestone region • Describe a stalactite

  27. Exam Questions • With reference to the Irish landscape, examine how the process of weathering has influenced the development of any one limestone feature. (30m) • Examine with reference to an example you have studied, the formation of one rock type and how it produces a distinctive landscape. (30m) • Explain with the aid of diagrams, how any two underground landforms, found in a Karst region are formed. Give a named example of each in your answer. (40m- OL)

More Related