9 Karst Landscape The formation of karst landscapes Examples of karst regions in Ireland and around the world Distinctive landforms found on the surface and subsurface in a karst environment The life cycle of a karst landscape
Chapter 9: Karst Landscape Karst topography = An area of exposed limestone on the surface of the land
Chapter 9: Karst Landscape Example of karst region= The Burren, Co. Clare Chapter 9: Karst Landscape
Chapter 9: Karst Landscape Formation Limestone is permeable Carbon dioxide (CO2) dissolves in rainwater Forms weak carbonic acid (acid rain) Carbonic acid/rainwater passes through rock – rocks dissolved by carbonation Cracks in rock become enlarged Underground drainage system develops Chapter 9: Karst Landscape
Chapter 9: Karst Landscape Surface landforms Limestone pavement Exposed area of limestone Rugged and bare landscape with flat areas of rock surface
Chapter 9: Karst Landscape Formation Carbonation (chemical weathering) Rainwater mixes with carbon dioxide in the air Forms a weak carbonic acid limestone is dissolved Joints and cracks (i.e. bedding) are widened by the rainwater e.g. the Burren, Co Clare
Chapter 9: Karst Landscape Features of limestone pavements Clint: section of a limestone pavement separated from adjacent sections by grikes Grike: vertical crack that develops along a joint in limestone Karren: small hollow that forms on the surface of a limestone clint
Chapter 9: Karst Landscape 2. Swallow holes River reaches an area of permeable rock Disappears down through grikes Grikes made bigger by solution (carbonation) Forms swallow hole (sluggas/sinkholes) e.g. Poll na gColm in the Burren, Co. Clare
Chapter 9: Karst Landscape Underground landforms 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
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Chapter 9: Karst Landscape 2. 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 pillars hanging down from the roof of the cave Stalagmites Water droplets fall to the cave floor Over time deposition of calcite form pillars growing upward from the cave floor form directly below stalactites
Chapter 9: Karst Landscape 2. Dripstone features (continued) 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
Name of location? Size of area? When was it formed? Type of rock? General features? Famous caves?
Chapter 9: Karst Landscape 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
Chapter 9: Karst Landscape Cycle of erosion in a karst topography Three stages: Youthful Mature Old age
Over ground features Underground features Type of rock Type of weathering Famous example