Limestone landforms

Limestone landforms

1. Surface landforms

   • Limestone pavement
     • Presence of joints and bedding planes
       • Acidic water passes through joints, widening joints
         • Joints widen to form gaps called grikes
       • In between 2 grikes, there are no joints (only bedding planes)
         • Acidic water cannot infiltrate
           • Forms Impermeable limestone blocks called clints
             • Over time, many clints and grikes together form limestone pavement
     • Occurs in temperate regions with low precipitation and thus low CW
   • Dolines
     • Where does carbonation & solution take place?
       • Limestone surface
         • Closed depression dolines
           • Usually round or cylindrical
             • SINKHOLE DOLINES
       • Sub-surface of limestone
         • Slope inwards @ 20 and 30 degrees
           • SOLUTION DOLINE
     • COLLAPSE DOLINE
       • Roof of sub-surface cave collapsed
         • Doline with vertical walls
     • Adjacent dolines intercept to form uvala
     • Extensive depression of dolines form polje
     • Tropical region
   • Cockpit Karst
     • More dense joints
       • Rate of CW is faster
         • Forms depressions called cockpits
     • Tropical region
       • High temp, high rainfall, a lot of vegetation
         • Increase formation of carbonic acid & humic acid
     • Less dense joints
       • Rate of CW is slower
         • Forms low elevation conical hills
   • Tower Karst
     • Continuation of cockpit karst
       • 30m-300m tall
       • Steep-sided due to deepening of cockpits
       • Tower karsts separated from one another by flat plains, rivers, swamps
     • When acidic water moves vertically downwards, further deepens cockpits
       • Until hits water table
         • Water stops flowing vertically and starts moving laterally, widening cockpit
           • Forms flat plains, swamps and rivers
             • EXAMPLE: Halong Bay, Vietnam (150m tall)

2. Sub-surface landforms

   • Caves