ABSTRACT
Solution caves occur widely in limestone and gypsum, and, less commonly, in salt, quartzite, and clastic rocks cemented by soluble material (e.g. some sandstones and conglomerates). Although dissolution is the dominant process, other processes such as erosion and gravitational breakdown may take part in their development, particularly at later stages. The lower limit of the size of a conduit (the precursor to a cave) is accepted to be about 5-15 mm. This range encompasses the important thresholds which permit turbulent flow through initial openings under common hydraulic gradients and temperatures, switch calcite dissolution kinetics to boost up the growth rate, and trigger effective sediment transport (Ford, 1988; Palmer, 1991; White, 1977; 1988; see also entry on Speleogenesis). It therefore allows conduits to be distinguished from proto-conduits, and from pores that form during diagenesis of sediments. Speleogenetic consideration implies that conduits can be partly or entirely filled by water, air, and sediments during various stages of their development.
