Dissolution tubules: A new karst structure from the English chalk

The Chalk of England is not renowned for producing karst landforms. This pa per introduces a previously undescribed karst phenomenon, termed here disso lution tubules, from the Chalk of Sussex. The internal structure of these f eatures was investigated by developing a novel method of resin impregnation and acid digestion. This revealed tubules to be a truly dendritic landform . Their relationships with chalk macrotextures were investigated using the Bushinski oil technique (BROMLEY 1981) and revealed an association with tra ce fossil burrows. Detailed electron microscopic examination of chalk adjac ent to the karst surface, employing the textural analysis methods of MORTIM ORE & FIELDING (1990), revealed dissolutional textural modification of the chalk to a depth of approximately 15 mm beneath the dissolution surface and a possible spatial association of dissolution tubules with microfractures. Dissolution tubules in the field were found overlying major discontinuitie s such as subhorizontal sheet flints, marl seams, hardgrounds, major fractu res and caves. Evidence gathered suggests mixing corrosion (BOGLI 1964) as the process responsible for their formation.