The Atacama Desert of western South America is an extreme environment that spans from the western flank of the Andes Mountains to the Pacific coast. Where annual rainfall is less than 5 mm, there is no plant life, and water almost never flows either in abandoned stream channels or on hill sides. Given millions of years of time to act, the Atacama Desert processes that shape the landscape and develop soils create a mixture of materials on the desert floor that are unique. By studying the record of landforms and soils in a valley in which sediments are trapped, authors Teresa E. Jordan and colleagues demonstrate that the Atacama Desert has been hyperarid for 12 million years. Yet, like all other places on Earth, the climate changed repeatedly. Whereas the growth of height of the Andes Mountains may have set in place a necessary condition to initiate extreme aridity, it is likely that changes in the temperature of the Pacific Ocean set the pace for the repeated climate shifts of the last six million years.
Age and eruptive center of the Paeroa Subgroup ignimbrites (Whakamaru Group) within the Taupo Volcanic Zone of New Zealand
D.T. Downs et al., School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Published online 1 Apr. 2014; http://dx.doi.org/10.1130/B30891.1.
The Whakamaru Group ignimbrites are the result of the largest rhyolitic eruption within New Zealand and one of the largest eruptions of the past million years. This study by D.T. Downs and colleagues demonstrates that this eruptive episode was more prolonged and complex than previously documented. There were at least two distinct eruptive episodes from geographically separate vents. The distribution and locations of vent derived lithic clasts within the young
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Geological Society of America