The history of the Edwards Aquifer is written in the DNA of its endemic cave spiders. White et al. present the first interdisciplinary study of its kind linking the biological evolution of endemic cave fauna with the hydrologic evolution of their vadose-zone aquifer habitat. Techniques originally developed for endangered species management have been applied in a novel approach to vadose-zone hydrology and paleohydrology. By establishing the synchrony between the speciation of cave fauna and the activation of discrete segments of the aquifer recharge zone, White et al. present a new set of tools to hydrologists and to managers of an aquifer resource serving more than a million people.
Largest wind ripples on Earth?
Juan Pablo Milana, InGe-CONICET, Universidad Nacional de San Juan, 5401 San Juan, Argentina. Pages 343-346.
Strong wind action has been the theme for many popular movies. However, we still do not fully understand the complicated interaction between strong winds and Earth's surface. The largest wind ripples found on Earth, and perhaps the coarsest grained, are described in the study by Milana. The wind ripples are found in the southern Argentinean Puna Plateau and reach 43 meters of crest spacing, helping fill the gap between the previously largest ripples described on Earth (over 20 meters) and the huge wind ripples found on Mars, reaching over 60 meters wavelength. Large wind ripples, which form under fast winds and the presence of lightweight volcanic grains transported by the wind, may help in understanding the formation mechanisms of these large bedforms, which are also considered to be sisters of the small wind ripple commonly formed in beach sand and dunes. Continued study may help in the understanding of the effect of very strong winds on surfaces with movable materials.
Bioapatite 87Sr/86Sr of t
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Geological Society of America