Karst Landscapes

Question 1

Shaping a limestone landscape

Answer 1

-carbonation
- weak carbonic acid reacts with calcium carbonate to become calcium bicarbonate (dissolved and removed from rock in solution)
- limestones that have a high % of calcium form the best karst features
- where the vegetation cover of a limestone landscape is thin/absent, freeze-thaw action occurs
- as joints + bedding planes enlarged, more water is able to flow through (hydraulic action + abrasion)
-effects of carbonation, seen best in areas of exposed limestone (burren)

Question 2

Surface landforms- limestone pavement

Answer 2

• large flat area of limestone that has had its soil cover removed and has been exposed at the surface over a long period of time
  -stratified rock. Rainwater is able to trickle freely through joints + BP
• carbonation = concentrated in these areas. (Joints widen + deepen —> grikes) (rest of area more resistant so stays flat topped blocks —> clints)
  Karrens- hollows on clints
  Fluting - channels that run into edge
  Eg. Burren

Question 3

Surface landforms - swallow holes + dry valleys

Answer 3

Swallow hole - opening in the bed of a river through which the river disappears from surface to flow underground (impermeable rock meets limestone) - carbonation, hydraulic action, abrasion
Dry valley - the section of river valley that lay downstream of a swallow hole had now lost its water supply (hydraulic action, abrasion)

Question 4

Underground landforms - caves

Answer 4

Naturally formed underground passage that is large enough to enter
Acts as a channel for water flowing underground from a swallow hole

Question 5

Underground landforms - caverns

Answer 5

Acidified water dissolved limestone - carbonation - water follows joints + BP —> cave
As cave enlarged, water flows faster (hydraulic action, abrasion)
If water flow is turbulent, sections of the roof of the cave will collapse to
form a cavern (large chamber)
Eg. Mitchelstown cave

Question 6

Calcite formations

Answer 6

Weak carbonic acid reacts with calcium carbonate in limestone as it passes through the rock. When the water seeps through the joints into the roof of a cave/cavern, it drips from the ceiling. Some carbon dioxide is lost by evaporation. Remaining water is unable to hold all calcium bicarbonate in the solution. Tiny amounts of pure limestone (calcite) are left behind. Drip stone features
- stalactites
- stalagmites
Eg. Mitchelstown cave (Tipperary)

Question 7

Stalactites

Answer 7

Hangs from the roof of a cave/cavern. Formed when water saturated with calcium bicarbonate hangs from the ceiling for a few seconds. When carbon dioxide evaporates, tiny ring of calcite is left (water drop shape) and solidifies. Process continues and calcite begins to grow

Question 8

Stalagmites

Answer 8

When drops of water hit the floor, more carbon dioxide evaporated and deposits of calcite build up from the floor. Domed shaped. Thicker than stalactites

Question 9

Pillars

Answer 9

As time passes, stalactites and stalagmites grow to join