The Inception Horizon Hypothesis in vertical to steeplydipping limestone: applications in New South Wales, Australia

The Inception Horizon Hypothesis has generally been applied to explain cave morphology in horizontal or gently-dipping limestones. When applied to vertical or steeply-dipping limestones, the Inception Horizon Hypothesis offers explanations for many characteristic features of the small impounded karsts found in the Eastern Highlands of New South Wales, Australia. In vertical or steeply-dipping limestones a limited number of pathways through the limestone are available, resulting in the development of multilevel passages and an increased likelihood of modern caves intersecting and/or exhuming palaeokarstic features. The few hydrological pathways through the limestone are easily blocked by sediment, abundant in small, impounded karsts, resulting in flow switching with surface streams and the consequent development of lateral dry valleys. Partial sediment blockage will result in paragenetic enlargement of passages, allowing relatively small streams to produce large, out-of-scale conduits with a "keyhole" cross-section, and paragenetic loops that can be misinterpreted as phreatic loops.