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The formation of karst landscapes The formation of karst landscapes
Examples of karst regions in Ireland and around the Examples of karst regions in Ireland and around the world world
Distinctive landforms found on the surface and Distinctive landforms found on the surface and subsurface in a karst environment subsurface in a karst environment
The life cycle of a karst landscape The life cycle of a karst landscape
99 Karst LandscapeKarst Landscape99 Karst LandscapeKarst Landscape
Chapter 9: Karst LandscapeChapter 9: Karst Landscape
Karst topography =Karst topography =
An area of exposed limestone on the surface of the land
Chapter 9: Karst LandscapeChapter 9: Karst Landscape
Example of karst region= The Burren, Co. Clare
Chapter 9: Karst LandscapeChapter 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 LandscapeChapter 9: Karst Landscape
SurfaceSurface landformslandforms
1. Limestone pavement Exposed area of limestone Rugged and bare landscape with flat areas of rock
surface
Chapter 9: Karst LandscapeChapter 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 LandscapeChapter 9: Karst Landscape
Features of limestone pavementsFeatures 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 LandscapeChapter 9: Karst Landscape
2.2. Swallow holes 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 LandscapeChapter 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
Chapter 9: Karst LandscapeChapter 9: Karst Landscape
2. Dripstone features
StalactitesStalactites 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
StalagmitesStalagmites 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 LandscapeChapter 9: Karst Landscape 2. Dripstone features (continued)
PillarsPillars
Stalactites and stalagmites grow towards each other
Eventually join to form a pillar or column
CurtainsCurtains
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 LandscapeChapter 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 LandscapeChapter 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