9 Karst Landscape The formation of karst landscapes

9 Karst Landscape The formation of karst landscapes Examples of karst regions in Ireland 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

Example of karst region= § The Burren, Co. Clare Chapter 9: Karst Landscape

Formation § Limestone is permeable § Carbon dioxide (CO 2) 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 1. Limestone pavement § Exposed area of limestone § Rugged and bare landscape with flat areas of rock surface

Formation Chapterweathering) 9: Karst Landscape § Carbonation (chemical § 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 g. Colm in the Burren, Co. Clare

Chapter 9: Karst Landscape Underground landforms 1. 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 § Drops of water lose carbon dioxide and deposit calcite § 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 Type of rock Underground features Type of weathering Famous example