Date:11/14/2012

in glaciers respond to climate change by rapidly advancing or receding as temperatures vary, and this change in glacier extent controls hydrology, sediment transport, and deposition in rivers downstream. The sedimentary record in glaciated catchments therefore represents an important archive with which to unravel past climate change. However, unlike rivers, whose flow is controlled entirely by land surface topography, glaciers are able to flow uphill and across ridgelines -- a process called "transfluence." Glacier advance and recession can result in drainage capture by transfluent ice flow, and so change catchment drainage areas and hydrological budgets. Ann Rowan and colleagues use a 3-D glacier model of ice flow during the last glaciation in adjacent catchments in the Southern Alps of New Zealand to find that glacial-drainage capture is a more important control on hydrology and the sedimentary record than climate change alone. These results from New Zealand demonstrate how scientists can use the sedimentary record to investigate past climate change both in this mid-latitude Southern Hemisphere location and in glaciated settings worldwide.

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Reappraisal of the relationship between the northern Nevada rift and Miocene extension in the northern Basin and Range Province

Joseph P. Colgan et al., U.S. Geological Survey, Menlo Park, California 94025, USA. Posted online 13 November 2012; doi: 10.1130/G33512.1.

For the past 17 million years and perhaps longer, motion of Earth's tectonic plates has moved California west, away from Utah and Arizona. As the area in between grew wider, Earth's crust cracked along major faults to form the mountains and valleys of the Basin and Range Province that today cover Nevada and western Utah. In the early stages of this process, large amounts of molten basalt intruded Earth's crust in northern Nevada, forming a linear, near-vertical dike swarm over 500 km long. This structure -- named the "northern Ne
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Contact: Kea Giles kgiles@geosociety.org Geological Society of America Source:Eurekalert

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