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A widespread biotic turnover occurred around the time of the Sturtian glaciation. Microfossil analyses show that one regional extinction pre-dates the glacial advance, challenging the more severe models for glacial effects in the Neoproterozoic era.
Millions of people in southern Asia rely on arsenic-contaminated groundwater to live. Massive water withdrawals through wells may be increasing the problem by drawing arsenic-mobilizing substances into shallow aquifers and arsenic-contaminated shallow groundwaters into deeper aquifers.
In the world of Web 2.0, the variety of channels for communicating science is exploding. Technology can help to generate images that attract attention, but there is much more to reaching the public than pretty pictures.
Ice clouds significantly affect the Earth's radiative forcing, but which particles lie at the core of the ice crystals is a matter of debate. In-flight spectroscopy suggests that biogenic materials contribute to ice formation in clouds.
The lack of strong splitting of seismic shear waves below central Nevada is in marked contrast to the surrounding region. Seismic data and numerical experiments suggest that a skinny, cylindrical drip of lithosphere may be to blame.
The complex three-dimensional structure of the Earth's solid inner core reveals how it has grown through time. Numerical simulations of the solidification process suggest that part of this structure has resulted from recent tectonic activity.
Remnants of the Laurentide ice sheet lasted until about 7,000 years ago. Climate simulations show that they caused the multimillennial delay between maximum early Holocene solar radiation and temperatures evident in Northern Hemisphere proxy records.
Paradoxically, as the International Polar Year ends we enter its most important phase. Now we must decide — and quickly — which mix of observations to sustain, based on what we have learnt.
John West and colleagues struggled with widely held misconceptions and computer hackers in their attempt to explain mantle processes beneath the Great Basin in the United States.
A dramatic oceanic biotic shift from eukaryotic phytoplankton to bacteria occurred about 740 million years ago. Microfossil and geochemical data from the Chuar Group in the southwestern United States link this biotic turnover to widespread eutrophication of surface waters.
The interglacial period that occurred about 400,000 years ago—Marine Isotope Stage 11—was the longest out of the past five glacial cycles. A proxy-based alignment of this interglacial with the Holocene, and a subsequent analysis of carbon isotopic data from marine sediments, indicates that the unusual length may have been driven by strong poleward oceanic heat transport.
Seismic anisotropy data for the Great Basin region of the western United States, coupled with tomographic images, help delineate a northeast-dipping lithospheric drip. Numerical experiments suggest that the drip could have formed owing to gravitational instability triggered by a density increase of about 1% and a temperature increase of about 10%.
Structures formed during ancient tectonic events are commonly reactivated during subsequent tectonism. Numerical models point to mechanical anisotropy arising from the inherited orientation of crystals of the mineral olivine in the lithospheric mantle as the cause of this behaviour.
