News & Views

Whether convection in the Earth's mantle extends through its entire depth or if the mantle is layered has long been debated. Recent research suggests that spatially and temporally intermittent or partial layering is the most likely solution.

Earthquake data seem to reveal a huge sausage-shaped slab of material detaching itself from the material subducting as two plates meet beneath the Hindu Kush. This largest-ever 'boudin' could tell us more about what happens when continents collide.

Numerous long, wall-like ridges can be observed in the Valles Marineris region of Mars. They probably represent fault zones cemented by water-deposited minerals and are indicative of ancient groundwater flow.

Deltas are among the most valuable coastal ecosystems, but they are very dynamic and the factors that influence their health are complex. The rate of compaction of underlying sediments might be a more significant factor than was thought.

Lakes dammed by ice will commonly spill in catastrophic outbursts. Lake Agassiz-Ojibway, at the margin of the Laurentide ice sheet, burst 8,470 years ago in a subglacial flood whose marks have been scratched into the seafloor of Hudson Bay.

The influence of global warming on temperature trends at higher altitudes has been hotly debated. Stratospheric ozone depletion is another piece in the remaining tropical climate puzzle.

Ice-sheet stability is affected by a complex interplay between meltwater and the geological characteristics of the bedrock under the ice. The identification of a recently active subglacial volcano in Antarctica adds uncertainty to this system.

Local changes in the velocity of ambient seismic noise just before volcanic eruptions could indicate increased magma pressure within volcanoes. Continuous monitoring of such changes may therefore prove to be a potent tool for forecasting eruptions.

In the auroral region, solitary plasma waves form in a low-density plasma when energetic electron beams hit and energize ambient ions to escape velocity. Electromagnetic waves from lightning trigger similar plasma behaviour in the equatorial ionosphere.

Impact craters often have asymmetric shapes, which have been used to infer the direction and angle of impact. But pre-existing structural or topographic heterogeneities also play an important role in crater asymmetry.

Rising carbon levels contributed to profound climate change 55 million years ago. Where did that extra carbon come from? One proposal — a cometary impact — is rebuffed by two analyses of magnetic particles in clay sediment cores from New Jersey.

India and Arabia collide with Eurasia at slightly different velocities. Detailed mapping of the Arabian Sea suggests that this motion started between 3 and 8 million years ago, possibly with a transfer of an Arabian plate wedge to the Indian plate.

In aerosol hot spots around the globe, solar radiation is dimmed down on its way to the Earth's surface. The resulting surface cooling turns out to be almost in balance with heating of the atmosphere due to black carbon.

Neither recycled oceanic crust nor sediments alone can explain the composition of ocean-island basalts, but how about a mixture of the two? Recent modelling using the isotopes of hafnium and neodymium appears to support this contention.

Modern deep waters form in the Nordic seas when high-salinity surface waters cool and sink. An analysis of Arctic Ocean sediments suggests that throughout the past fifteen million years, brines created during sea-ice formation controlled the sinking of water.

The atmosphere's lowermost 10 km have long been assumed to be almost solely responsible for weather and climate on Earth. Emerging evidence points to the layer above as an important influence on surface winds and temperatures on seasonal to decadal timescales.

From about 470 million years ago, the Middle Ordovician period witnessed a rapid increase in biodiversity. This explosion in numbers of species is almost perfectly contemporaneous with an increased frequency of meteorite impacts.

The relationship between carbon dioxide and climate over millions of years has been a source of controversy. Fossilized liverwort leaves can help illuminate both temperature and atmospheric carbon dioxide levels from 200 to 60 million years ago.