Shore platform denudation measurements along the Maltese coastline

Abstract

Using an original rock profiling technique especially adapted to locally common smooth and irregular / deeply weathered (karstic) rocky shores, 38 base-line profiles were established at 19 rocky-shore sites to investigate surface-denudation characteristics exhibited by natural rock surfaces found on the Maltese coast. The latter were identified as being representative of actual or potential bathing platforms, thus offering a valuable alternative to otherwise scarce beach environments on the tourist rich Islands of Malta. Observations on shore surface denudation over a 3 – 5 year period were subsequently related to degree of exposure, erosion and weathering processes considered active at each site. Identification of distinct surface-denudation characteristics for sub-divisions within the Globigerina Limestone and similar surface-lowering rates for Lower Coralline Limestone and the Lower Globigerina Limestone sub-division were considered to qualify otherwise subjective interpretation of local bedrock resistance to marine erosion and weathering. The design of an innovative 'Rock Profiler', was identified as an improvement to traditional profiling techniques, allowing surface elevation measurements over both smooth and indented rock surfaces, achievements of more representative rock surface profiling over extended sample areas (with a 95 consecutive point line-transect), accurate assessments of rock surface micro-relief and of carrying out profiling independent of rock surface plane. This study provided for the first time, accurate and distinct surface-denudation rates for the main geological formations exposed on the Maltese coast, these being 1.38mm/yr for Upper Coralline Limestone, 9.16mm/yr for Middle Globigerina Limestone, 0.74mm/yr for Lower Globigerina Limestone and 0.77mm/yr for Lower Coralline Limestone.