Geology

The Earth's core formed under more oxidizing condition's than previously believed, researchers have discovered through of series of laser-heated diamond anvil cell experiments at high pressure - 350,000 to 700,000 atmospheres of pressure - and temperatures - 5,120 to 7,460 degrees Fahrenheit. Scientists know that the Earth accreted from some mixture of meteoritic material but there is no simple way to quantify precisely the proportions of these various materials. The new research defines how various materials may have been distributed and transported in the early solar system. As core…

During an earthquake, waves emitted when the two sides of a fault move—or slip—rapidly past each other, create ground motion, with an average relative speed of about three feet per second. Not all fault segments move so quickly. Some slip slowly, through a process called creep, and are considered to be "stable," or not capable of hosting rapid earthquake-producing slip.  One common hypothesis suggests that such creeping fault behavior is persistent over time, with currently stable segments acting as barriers to fast-slipping, shake-producing earthquake ruptures.  A new study by…

In 1991, the Pinatubo volcano eruption was a disaster for the Philippines and the effects were noticed across the world - it threw tons of ash and other particles into the atmosphere, which caused less sunlight to reach the Earth's surface. Global temperatures dropped by half a degree for years after that. Clearly, volcanic eruptions can have a strong short-term impact on climate but a group of researchers are delighting doomsday believers by contending climate change will have an impact on volcanic eruptions. The researchers from GEOMAR Helmholtz Centre for Ocean Research Kiel and Harvard…

A new study indicates that clay minerals, formed when water is present for long periods of time, cover a larger portion of Mars than previously thought. Clays were in some of the rocks studied by Opportunity when it landed at Eagle crater in 2004. The rover only detected acidic sulfates and has since driven about 22 miles to Endeavour Crater and clay minerals have been detected using a spectroscopic analysis from the Mars Reconnaissance Orbiter. The clays also exist in the Meridiani plains that Opportunity rolled over as it trekked toward its current position.  The clay signatures near…

Giant crevasses that penetrate upward from the bottom of the   Larsen C Ice Shelf, the largest remaining ice shelf on the Antarctic Peninsula, make it more susceptible to collapse, according to researchers who spent the last four Southern Hemisphere summers studying the massive floating sheet of ice that covers an area twice the size of Massachusetts. But the scientists also found that ribbons running through the Larsen C Ice Shelf, made up of a mixture of ice types that, together, are more prone to bending than breaking, make the shelf more resilient than it otherwise would be. The…

The Grand Canyon is spectacular to look at but figuring out how old it is can be frustrating. A new paper says that conventional models and estimates of the last 150 years are way off - it is far older than the 5 to 6 million years old commonly thought. "Rather than being formed within the last few million years, our measurements suggest that a deep canyon existed more than 70 million years ago,"  says Kenneth A. Farley, Keck Foundation Professor of Geochemistry at Caltech and coauthor of the study. The team used a new method to test ancient rocks found at the bottom of the canyon's…

In the early 1990s, scientists were surprised to find that areas near Mercury's poles were unusually bright when observed with radar from Earth, a potential indication that ice might be present.  New research in Science sheds some light on the long-standing issue of ice on Mercury. Several independent lines of evidence now reveal that the sun-scorched planet has extensive water ice deposits at its poles. Planetary scientists have identified water ice and unusually dark deposits within permanently shadowed areas at Mercury's north pole, according to analyses of data collected by NASA's…

Mountain glaciers respond to climate change by rapidly advancing or receding as global temperatures have spiked upward and downward numerous times throughout geological history. Those changes in glacier extent control hydrology, sediment transport, and deposition in rivers downstream.  The sedimentary record in glaciated catchments therefore is an important archive with that can help unravel past climate changes but, unlike rivers, whose flow is controlled entirely by land surface topography, glaciers are able to flow uphill and across ridgelines - a process called "transfluence."…

The El Niño-Southern Oscillation (ENSO) drives many of the catastrophic climate events that occur from one year to the next: floods, droughts, wildfires, and hurricanes.  However, climate scientists do not yet know how ENSO will respond to climate change. A new multi-century reconstruction of ENSO variability, based on fossil corals from Papua New Guinea, reveals a century-long decline in the number of El Niño events starting in the mid-1500s. It is the first time such a shift in activity has been documented in either modern observations or past reconstructions. This reduced activity…

Did the flood waters from melting of the Laurentide Ice Sheet in the last major cold episode on Earth about 12,900 years ago flow northwest into the Arctic firs, or east via the Gulf of St. Lawrence to weaken ocean thermohaline circulation and have a frigid effect on global climate? It's a debate that has gone on for decades but new, high-resolution global ocean circulation models claim to have an answer/  The researchers report that the flood must have flowed north into the Arctic first down the Mackenzie River valley. They also say that if it had flowed east into the St. Lawrence River…