DEFINITION AND PROCESS-BASED CLASSIFICATION OF CAVES.

A new definition of the term "cave" enables its linking to recognised cave formation processes, its coverage of the known cave types, its differentiation from porosity and contiguous spaces, and its applicability within a continuum of sizes, as well as ensuring avoidance of explorational bias. Despite its scientific basis, the proposed definition remains straightforward enough to be used by cavers and by non-specialists. Guided by this definition, a proposed hierarchical classification scheme, which is also process-based, combines the known cave types. The hierarchy is based upon five levels of classification, wherein the first two levels define the major cave categories. Further branching encompasses variation in cave development settings and in agents of cave formation. Discussion of various pre-existing classifications and definitions reveals the non-static nature of such schemes, which tend to evolve in response to the progress of cave research. The key is in increases in cave census data and improved communication by and between scientists about previously and newly discovered caves. [ABSTRACT FROM AUTHOR]