HARPER, Stephen B., Department of Geology, East Carolina University, Greenville, NC 27858,

    The landscape in Krabi Province in southern Thailand is characterized by steep, limestone headland cliffs along its shoreline and by limestone (karst) towers both offshore from the headlands and inland along its alluvial plains. The coastal karst towers rise directly out of the shallow waters of Phang Nga Bay or emerge from mangrove-fringed tidal flats whereas the inland karst towers are surrounded by Quaternary alluvial and colluvial deposits.
    The tower karst in Krabi is developed in massive Permian limestone and dolomitic limestone of the Ratburi Group. These folded carbonate beds strike northeast-southwest and dip gently to moderately to the northwest and southeast.
    Two varieties of tower karst are prominent in the Krabi region, peak forest karst (isolated peaks) and peak cluster karst (group of peaks with a common rocky base). In the peak forest karst the most common peak shapes are tall, vertical-sided, cylindrical-shaped towers (Turm karst) and moderately steep-sided, cone-shaped towers (Kegel karst). The peak forest towers have maximum elevations that range from about 60 to 210 meters above mean sea level. The peak cluster karst exhibits cone- and cylindrical-shaped peaks on broad masses of limestone. Some of these masses are elongated along the northeast-southwest direction of strike of the Ratburi Limestone and often have vertical cliff faces along their margins. The maximum elevations of the peak cluster towers range from about 240 to 400 meters above mean sea level.
    In some locations the cylindrical- and cone-shaped towers occur adjacent to each other. This morphology supports the argument that peak shape of tower karst is controlled mainly by lithologic factors (e.g., massiveness of beds and porosity) rather than climatic factors. The evolution of the cylindrical-shaped towers is also maintained by spalling of tower walls.
    The lower maximum elevations of the peak forest karst and its relative spatial proximity to the peak cluster karst suggest that the peak forest evolved from the peak cluster as a later stage of karst landform development. However, late Quaternary sea level changes have also influenced karst development in the Krabi region by exerting controls on fluvial erosion-deposition cycles, water tables, and supply of allogenic surface waters.