1. Chapter 9: Karst Landscape
Karst topography
Exposed limestone
Dissolving of carbonate rock

2. Chapter 9: Karst Landscape
Examples of karst regions
The Burren, Co. Clare and Marble Arch, Co. Fermanagh

3. Chapter 9: Karst Landscape
Formation
Limestone is permeable
Carbon dioxide (CO2) dissolves in rainwater
Forms weak carbonic acid
Percolates through rock – rocks dissolved by carbonation
Fissures in rock become enlarged
Underground drainage system develops

4. Chapter 9: Karst Landscape
Surface landforms
Limestone pavement
Exposed area of limestone
Rugged and bare landscape with flat areas of rock surface

5. Chapter 9: Karst Landscape
Formation
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, limestone is dissolved
Joints and cracks (i.e. bedding) are widened by the rainwater
e.g. the Burren, Co Clare

6. 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

7. 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
Dry valley = remains of river valley downstream
from sinkhole
River of resurgence = where river reappears
at the surface

8. Chapter 9: Karst Landscape
Subsurface 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

9. 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

10. 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

11. 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

12. Chapter 9: Karst Landscape
Cycle of erosion in a karst topography
Three stages:
Youthful
Mature
Old age

13. Chapter 9: Karst Landscape
1. Youthful stage
Rivers flowing on the surface
Erosion of impermeable rock
Then erosion of permeable rock (limestone)
Chemical weathering (carbonation)
Formation of swallow holes

14. Chapter 9: Karst Landscape
2. Mature stage
Dry valleys on the surface
Sink holes

15. Chapter 9: Karst Landscape
3. Old age stage
Weathering
Removal of limestone
Older more resistant rock left prominent – hums
Rivers once again flow over the surface