The factors that form karst caves also leave their traces on the interior surface of the caves. These traces are called rock features. Rock features combine to create the overall relief, the shape of the interior surface of a cave. Rock features and rock relief therefore offer the first and often even comprehensive explanation of the formation and development of the caves that characteristically hollow karst aquifers.
 

Although the two conditions given in the title, ‘Large Epigenic Caves’ and ‘High-Relief Area’, already considerably narrow down the caves that fall within these categories, it quickly becomes clear that the geomorphology of such caves is not clear from the beginning. A closer look into the literature actually reveals that diverse speleogenetic agents may influence the genesis of such caves. Vertical vadose passages as well as (epi) phreatic base-level control very commonly occur in large cavesin high-relief areas. The key to understanding the genesis of these caves is: (1) the notion of time (commonly such caves are old and may even present different distinct phases of evolution) and (2) the evolution of the surface around these caves. Commonly, caves in mountainous areas deliver hints to reconstruct the (spatial and temporal) evolution of the surface morphology. In that manner, caves in mountains and in lowlands are no different, but surface information within them ountains is generally much more rare because of the intensive erosional processes in such steeply sloping areas.

Halite is the most soluble common mineral. Salt karst is concerned with extremely soluble and erodible rock-salt geomorphology, which demonstrates a dynamic end member to karst processes. Salt outcrops are rare, due to the high solubility, and common total dissolution underground, but subsurface salt is common, and commonly associated with environmental problems. These are associated with salt hazards, generally due to anthropogenic modification of hydrological systems, causing aggressive water to attack salt rock. Most salt outcrops appear under desert conditions, where the salt mass escapes total dissolution. In such outcrops, runoff produces well-developed karst terrains, with features including karren, sinkholes, and vadose caves. Existing salt relief is probably not older than Pliocene, but the known well-developed

The methodologies based on the ideas of a karst dynamic system, which links the climate, geology, biosphere and karst formation, and the karst feature complex (KFC) that facilitates overcoming the confusion of isomorphism in establishing a geoclimatic gradient of karst landforms, are first introduced in this chapter. The karst in mainland China is selected as a training area to establish the climatic gradient of KFC. The reason to make such a choice is its having prerequisites such as karst developed on hard, compact carbonate rocks to facilitate preservation of landforms; karst that enjoys a clear climatic gradient in the late geological history; and an area without the scouring process of a continental ice sheet during the last glaciation. Then, the geological impacts from factors such as lithology, structure, paleography, and tectonism on climatic gradient are discussed. Finally, a global perspective is given as an attempt at a summary. 

Stone forests are unique karst surface landforms which range from several dozen to hundreds of square kilometers, and their distinctiveness is reflected in the number of denominations in different parts of the world including, for example, shilin, tsingy, and assegai. Diverse examples of stone forests show that the shape of the pillars, as tall as up to 100 m, is mainly the consequence of the distribution and density of fissures in the rock, its stratification, and different rock strata composition. We currently divide stone forests into three types: subsoil forests, uncovered forests, and bare forests. The rock forms on the pillars are according to their development divided into subcutaneous forms, forms shaped by rainwater and composed rock forms. The largest stone forests occur in tropical and subtropical conditions where corrosion of rock is the dominant factor and mechanical weathering is not pronounced. The Lunan stone forests developed from underground karren.

The Crimean Piedmont stretches along the tectonic suture separating the fold-and-thrust structure of the Crimean Mountains from the Scythian Plate. It comprises two cuesta-like ridges whose structural slopes are built up of homoclinal limestone beds of the Paleocene- Eocene (the Inner Range), and the Neogene (the Outer Range) ages. Abundant relicts of the hypogene karst have been identified recently in steep cuesta cliffs of the Piedmont. The hypogene cavities formed in confined to semi-confined hydrological conditions due to interaction of the deep-seated waters, ascending along cross-formational fracture conduits, with the strata-bound lateral filtration flow. The ongoing geomorphological dissection of the stratified structure of the Piedmont com-monly follows the pre-formed hypogene conduits, resulting in the development of the pronounced cuesta relief with steep cliffs featuring massive exposure of the hypogene karst conduit paleo-walls with specific morphologies.
Movement of deep-seated fluids through carbonate wallrock may cause isotopic altera-tion of the later. We have studied isotopic composition of C and O along nine cores drilled into the walls of the cliffs decorated with hypogene solutional features, as well as in two hypogene caves. Data from all cores show the presence of a wide isotopic altera-tion halo, whose thickness exceeds the core length (max. 40 cm). In this zone, the rock is slightly depleted in δ18Î (ca. 1 -2 ‰) relative to the “pristine”, unchanged values of a given rock unit. In most cores the rock is also depleted in 13Ñ but two cores show high-er 13C values. In addition to this low-gradient alteration, most of the cores also show a narrow (4-50 mm) zone of the high-gradient alteration, across which δ18Î and δ13Ñ drop by respectively, 2.0–4.9 ‰ and 0.7–4.5 ‰. At three localities, the walls of the hypogene cavities were coated with phreatic calcite. Isotopic composition of this calcite corresponds to the lowermost values of the altered rock. In one core, the rock in the high-gradient alteration zone is depleted in 18Î but enriched in 13Ñ. In yet another core the rock is enriched in both 18Î and 13Ñ. The results corroborate the hypogenic origin of conduits and suggest that the wallrock was exposed to, and interacted with, geo-chemically different waters after the main volume of cavities had been created by disso-lution.

The leading role in the geomorphic development of the Crimean fore-mountain region is played by the processes of dismemberment of “shielding” limestone layers of the monoclinal stratified structure through valley entrenchment, and by further retreat of vertical rocky outcrops via block-toppling mechanism. These processes are guided by the presense of hypogene karst structures, whose formation preceded the modern relief. Karstified fracture-karst zones, 100 to 400 m wide, in the Cretaceous-Paleogene strata controlled the entrenchment of valleys in the limestone layers. The basic elements of hypogenic karst structures, which form their spatial framework, are sub-vertical fracture-karst conduits (karst “rifts”). Denudational opening of vertical fracture-karst rift conduits in limestone layers set the cliff-like shape of valleys slopes, and presence of such rift conduits in the rear of cliffs of already incised valleys determines the block-toppling mechanisms of slope retreat. This maintains the verticality of cliff segments in the cuesta ridge and controls their position. Hypogenic sculptural morphology is extensively displayed in the exposed walls of cliffs (former conduit walls), which determines the originality and nomenclature of morphology of limestone cliffs of the Inner Ridge. In those areas of slopes where position of cliffs has stabilized for considerable time due to absence of new lines of block detachment in the rear, weathering becomes a significant process in the morphogenesis of surfaces. The abundance, outstanding expression, preservation and accessibility of relict hypogene karst features in the extensive cuesta cliffs of the Inner Ridge makes the region the foremost one for studying regularities of hypogene solution porosity development, the process currently ongoing in the adjacent artesian basin of the Plain Crimea.