A growing number of studies suggest that cave formation by deep-seated groundwater  (hypogene) is a more common process of subsurface water-rock interaction than previously  thought. Fossil hypogene caves are identified by a characteristic suite of morphological  features on different spatial scales. In addition, mineral deposits (speleothems) may provide  clues about the chemical composition of the paleowater, which range from CO2-rich to  sulfuric acid-bearing waters. This is one of the first studies to examine hypogene cave  formation in dolomite. Kozak Cave is a fossil cave near the Periadriatic Lineament, an area  known for its abundance of CO2-rich springs. The cave displays a number of macro-, mesoand  micromorphological elements found also in other hypogene caves hosted in limestone,  marble or gypsum, including cupolas, cusps, Laughöhle-type chambers and notches. The  existance of cupolas and cusps suggests a thermal gradient capable of sustaining free  convection during a first phase of speleogenesis, while triangular cross sections (Laughöhle  morphology) indicate subsequent density-driven convection close to the paleowater table Notches mark the final emergence of the cave due to continued rock uplift and valley  incision. Very narrow shafts near the end of the cave may be part of the initial feeder system,  but an epigene (vadose) overprint cannot be ruled out. Vadose speleothems indicate that the  phreatic phase ended at least about half a million years ago. Drill cores show no evidence of  carbon or oxygen isotope alteration of the wall rock. This is in contrast to similar studies in  limestone caves, and highlights the need for further wall-rock studies of caves hosted in  limestone and dolomite

Karst on the Nullarbor Plain has been studied and described in detail in the past, but it lacked the determination of the karst discharge and palaeo-watertable levels that would explain the palaeohydrological regime in this area. This study explores the existence of previously unrecognised features in this area – karst pocket valleys – and gives a review on pocket valleys worldwide. Initial GIS analyses were followed up by detailed field work, sampling, mapping and measuring of morphological, geological, and hydrological characteristics of representative
valleys on the Wylie and Hampton scarps of the Nullarbor Plain. Rock and sand samples were examined for mineralogy, texture and grain size, and a U–Pb dating of a speleothem froma cave within a pocket valley enabled the establishment of a time frame of the pocket valleys formation and its palaeoenvironmental implications. The pocket valleys document the hydrological evolution of the Nullarbor karst system and the Neogene–Pleistocene palaeoclimatic evolution of the southern hemisphere. A review of pocket valleys in different climatic and geological settings suggests that their basic characteristics remain the same, and their often overlooked utility as environmental indicators can be used for further palaeoenvironmental studies. The main period of intensive karstification and widening of hydrologically active underground conduits is placed into the wetter climates of the Pliocene epoch. Subsequent drier climates and lowering of the watertable that followed sea-level retreat in the Quaternary resulted in formation of the pocket valleys (gravitational undermining, slumping, exudation and collapse), which, combined with periodic heavy rainfall events and discharge due to impeded drainage, caused the retreat of the pocket valleys from the edge of escarpments.