Karst

• What are karst landscapes

  • Karst landscapes are characterized by the dissolution of soluble rocks, e.g., the Great Australian Bight
  • There exists 3 pre conditions for the formation of a karst landscape
  • Soluble rocks -> such as limestone or gypsum
  • Water
  • Secondary porosity features -> such as bedding planes, fractures or faults
  • Most drainage of karst surfaces is underground, which leads to dry conditions at the surface. The underground drainage in these landscapes is highly integrated, which contributes to the creation of elaborate subterranean morphologies
• Rock Dissolution

  • The transition of minerals into aqueous solutions requires water (or if a carbonate, carbonic acid)
  • Dissolution also requires CO2, soil is the major source of this CO2. As a result, karst features are most rapidly developed in CO2 rich regions, such as the tropics
  • Rainwater in soil reacts with the CO2 to create a weak acid, as it travels through the bedrock it dissolves it
  • Dissolution rates are dependent on
  • CO2 concentration
  • Temperature
  • Time and equilibrium (percolation)
  • Flow type (e.g. turbulent)
  • Soluble rocks
• Feedback of karst systems

  • Dissolution in these landscapes is an example of positive feedback loop. As the dissolution of rocks allows greater levels of CO2 to penetrate, which leads to more dissolution
  • Quartz and other silica materials can also be dissolved; however, their solution is much slower than carbonates and require high pH values
• Karst Caves

  • Cave networks develop near the ground water table and adjust to changes. Due to this cave systems can reflect how the water table level has changed over time
  • They typically form along joints, but network pattern can reflect the stratigraphy and bedding
  • Conduit caves are greater than 1cm in diameter and are responsible for moving water between the input and output region of karst systems
  • When solution reaches a cave, it precipitates calcium carbonate to form speleothems. These speleothems can record paleoclimate information such as moisture, weathering and temperature
• Tufa Deposit 


  • Formed as a response to the precipitation of carbonate underground they provide useful information about the active processes in an environment
  • Tufa is formed when carbonate minerals precipitate out of ambient temperature water that is saturated with calcite from CO2 degassing
  • Most commonly found in springs, fluvial channels, wetlands and lakes