40 NCKRI Special Paper No. 1 confined conditions of sluggish rising forced flow and homogenous hydraulic heads. Less dense and more aggressive water tends to occupy the uppermost position in the available space geometry, producing upward-directed imprints such as rising wall channels, ceiling half-tubes, and cupolas. Buoyancy currents begin from feeders – points from which water entered a cave or a particular story. Buoyant dissolution morphologies comprise a continuous series, well recognizable in caves where the original morphology was not much disrupted or obscured by later water table and vadose development, breakdown processes, or sedimentation. The morphologic suite of rising flow is best represented in limestone caves where thermal waters were involved, and in gypsum caves where the gypsum strata are underlain by an aquifer with relatively low solute load. Dead ends, abrupt changes in morphology and partitions Some morphologic features in caves, such as blind terminations of passages (dead ends), abrupt changes in size and morphology, and various kinds of bedrock partitions (vertical or horizontal) were always regarded as odd and puzzling by researchers accustomed to “lateral” speleogenetic thinking. They are difficult to explain within the conventional speleogenetic concepts of caves formed by lateral flow or by dissolution at the water table. These features are sometimes considered as attributive to sulfuric acid speleogenesis (e.g. Hill, 2003a, 2006, Hose and Macalady, 2006) but in fact, these are very common for most hypogenic caves regardless of the dissolution chemistry involved and host rock composition. These features are perfectly consistent with rising transverse speleogenesis; lateral changes simply indicate largely independent rising development of numerous transverse segments (flow paths), and vertical changes indicate variations in initial porosity structures across a vertical section. Blind terminations of passages are inherent elements in almost all maze caves (see cave maps throughout this book) and complex 3-D caves. In most cases they are “dead ends” only from a “lateral” perspective but in the transverse flow scheme they are open either to recharge (feeders from below; Plate 2, A-D; Plate 5, A-C) or to discharge (outlets to above). The transverse speleogenesis mechanism allows even a single, laterally isolated fracture to enlarge to a passable size by vertical flow through its entire length, but the passage will remain blind-terminated (pinching out) laterally at both ends (Figure 31-A). Partitions are thin separations between adjacent passages or chambers made up of bedrock or various kinds of planar resistant structures exhumed by dissolution, such as lithified fill of fractures or faults and paleokarstic bodies. They are common in many densely packed maze caves, where bedrock separations between passages are commonly thin (Plates 12 and 13). In the Western Ukrainian mazes, bedrock separations (“pillars”) between adjacent passages may be less than a meter thick (Plate 12, C though G). Sometimes they are only a few centimeters thick so that a “window” can be broken by a punch. When water table overprint was locally noticeable on transitional stages, thin partitions can be easily truncated by dissolution at the water table (Plate 12, E-G). Another type of partition is represented by projections of lithified fracture fill exposed by dissolution. They may largely or completely partition rather large passages (Plate 13). Common in some mazes of the western Ukraine, such partitions are quite fragile (being only a few centimeters thick). The fact that they remain intact, and passage morphology remains uniform on both sides of such partitions, indicates a homogenous head field within a mature cave system and an overall transverse flow pattern. Horizontal partitions by more resistant beds in a stratified sequence may create multi-story cave systems, where passages of different stories are closely spaced in a vertical cross-section (e.g. Endless and Dry caves in the Guadalupe Mountains, New Mexico, USA; Archeri Cave in the Minor Caucasus, Armenia; Coffee Cave in the Roswell Basin, New Mexico, USA, Stafford et al., 2008). Osborne (2003) described partitions of various kinds in Australian caves and recognized that caves containing vertical and subvertical partitions are likely to be formed by per ascensum speleogenetic mechanisms.
PLATE 1 MORPHOLOGIC SUITE OF RISING FLOW: FEEDERS Plate 1. Feeders: side feeders with rising wall channels. A = Optymistychna Cave, western Ukraine (Miocene Gypsum); B, D = Carlsbad Cavern, Guadalupe Mountains, NM, USA (Permian limestone); C = Fuchslabyrinth Cave, Germany (Triassic Muschelkalk limestone); E = Mystery Cave, MN, USA (Ordovician limestone); G = Dry Cave, Guadalupe Mountains, NM, USA, (Permian limestone); F, H = Deep Cave, TX, USA (Cretaceous limestone). Photos by A. Klimchouk. 41
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