The NSS Bulletin - ISSN 1090-6924
Volume 49 Number 2: 50-66 - December 1987

A publication of the National Speleological Society

Cave Levels and their Interpretations
Arthur N. Palmer

The concentrations of passages at common levels in a solution cave can be used to interpret the evolution of the cave in relation to its regional setting. It is usually assumed that cave levels of they type are controlled by fluvial base level, although stratigraphic influence must also be considered. High-precision vertical surveys that show past vadose/phreatic transition points (piezometric limits), rather than relative passage size alone, are needed from proper identification of levels. Stratigraphic perching can cause a false interpretation, but base-level control, where present, can be recognized even where the strata have a great influence. Although the largest passages in a cave owe their origin to increasing discharge rates, their ultimate size depends primarily on the length of time they have been active. Sharply defined cave levels with narrow vertical ranges, such as those in Mammoth Cave, Kentucky, appear to have formed in response to intermittent episodes of rapid valley entrenchment, probably by headward erosion, followed by a lengthy period of virtually static base level. Piezometric limits are adjusted to base-flow conditions and do not reflect short-term variation in river level or groundwater discharge. Most cave levels are not so distinct, owing to erratic or slow lowering of base level, or to large fluctuations in groundwater flow. Some levels in caves formed by short-lived deep-seated processes may not represent static base levels.

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