Development of coastal karst terrains in northern Malta

Abstract

Karst terrain features common landscape in the Maltese Islands, where 90 per cent of the total area is represented by carbonate outcrops (European Union Report, 1995), mostly limestone formations. Karst terrains can be subdivided into two main categories: inland karst and coastal karst, the latter being characterised by its proximity to the sea. The karstified areas have been identified from the orthomaps available on the Malta Environment and Planning Authority (MEPA) website and through site visits. This study deals with the development of coastal karst terrains in northern Malta. Two maps have been produced through the use of GIS to represent the main karst landforms and their distribution in the Maltese Islands. This exercise has helped to identify the coastal stretch that has been studied in detail for the purpose of this dissertation. The coastal stretch between Ramla tal-Bir and Rdum il-Hmar at L-Ahrax tal-Mellieha on the north of Malta, has been selected for detailed study. Karst processes and the resulting features occurring along the coastal stretch under study have been examined. A geomorphological map has been produced for the field site, this was divided into 13 zones for a more systematic analysis. This map shows a detailed distribution of karst features along the coastal stretch under study. Classifications were also proposed or the coastal area at L-Ahrax tal-Mellieha. Insoluble Residue Tests were performed on Upper Coralline Limestone samples collected at various points along the field site. The results obtained from the Insoluble Residue Tests have been analysed and interpreted within the context of the qualitative data derived from the field survey. The results helped to determine the average percentage of insoluble residue and thus the resistance of Upper Coralline Limestone to solution processes, which in turn influences the formation and extent of karstic features.