Karst is found wherever there is limestone. Carboniferous limestone is permeable. As rain goes down through the joints and cracks found in the limestone, it adds with CO2 that forms weak carbonic acid.
H2O + CO2 = H2CO3 (carbonic acid)
This reacts with certain minerals and becomes very effective especially with carbonic minerals like limestone that includes Calcium Carbonate CaCo3 or the mineral calcite. This mineral is highly soluble and dissolves when it comes in contact with water. Apart from water other agents such as bacterial decay of organic matter decomposition can form this. Solution is the dominant process in the formation of Karst Landscape.
Karst does not dissolve equally over the land surface as solution is concentrated along joints and cracks. So with time, solution enlarges these joints and cracks that will let water penetrate underground much more quickly. This increases further solution and erosion. As water keeps enlarging the voids, there will be the formation of caves and other landforms associated with limestone.
Basic features of Karst formation
This process also appears in the limestone found in the Maltese Islands. It appears best in the Upper Coralline Limestone and Lower Coralline Limestone as they have more joints and cracks.
Karst Landforms in the Maltese Islands
Three landforms found in the Karst landscape which are found in the Maltese Islands are:
Subsidence/ solution structures (Dolines)
Limestone pavements are found in the surfaces mostly in the Upper Coralline Limestone and Lower Coralline Limestone. They are also frequently found when there is lack of soil cover. Limestone pavements support garigue type of vegetation and have fresh water pools. Sometimes they also contain small patches of terra rossa soils. Limestone pavements are blocks of limestone that are full of horizontal bedding plains and vertical joints. Chemical weathering and erosion widen these plains and joints. The blocks are known as 'clients' and the gaps are known as 'gyres'.