Hypogene Speleogenesis in the Guadalupe Mountains, New Mexico and Texas, USA

The Guadalupe Mountains consist of an uplift of Permian carbonate shelf deposits in a semiarid landscape. A variety of speleogenetic processes, mostly hypogene, have made them one of the world’s best-known cave regions. The most notable caves are Carlsbad Cavern, which contains the largest known cave room in the USA, and Lechuguilla Cave, now the world’s 7th longest. Because the caves are no longer active, there was early confusion about their origin. This was resolved when long-dormant sulfuric acid processes were recognized, with H2S supplied by nearby oil fields. Potassium-argon dating of the by-product mineral alunite in the Guadalupes indicates speleogenetic ages from 12 to 4 million years, decreasing with lower elevation. Caves show abundant evidence for subaerial corrosion, both by sulfuric acid and carbonic acid in water films. Many seemingly phreatic features have resulted from this subaerial process. Microbial alteration of bedrock has contributed to weathering. There is evidence that isolated caves of greater age, lined by large scalenohedral calcite, were formed by supercritical CO2 in deep thermal water

Evidence based neonatal surgery

Surgical intervention has, quite rightly, a well-established role in the management of a number of congenital and acquired neonatal conditions. Surgical approaches have been developed over a period of time, from the initial endeavours of pioneering neonatal surgeons, to the procedures commonly in everyday use today. Such development has been predominantly a result of necessity, learning from past experience and translation of techniques in use in other surgical fields into neonatal surgery. As neonatal surgical experience has grown, surgeons have begun to develop alternatives to what were once thought to be traditional techniques such that for a number of conditions we now have the luxury of choice in the treatment of these often fragile infants. With choice, there comes a dilemma. Which approach should be used? How should we make the decision