In the introduction, University of Washington geologist David R. Montgomery writes that he never thought he’d write an optimistic book about the environment. Montgomery’s first popular book, “Dirt,” was about how erosion undermined ancient civilizations around the world in places like modern-day Syria and Iraq. (more…)
Tag Archives: geologist
The gusting westerly winds that dominate the climate in central Asia, setting the pattern of dryness and location of central Asian deserts, have blown mostly unchanged for 42 million years. (more…)
Impact glass stores biodata for millions of years
Bits of plant life encapsulated in molten glass by asteroid and comet impacts millions of years ago give geologists information about climate and life forms on the ancient Earth. Scientists exploring large fields of impact glass in Argentina suggest that what happened on Earth might well have happened on Mars millions of years ago. Martian impact glass could hold traces of organic compounds. (more…)
Geologic time is shorthand for slow-paced. But new measurements from steep mountaintops in New Zealand shows that rock can transform into soil more than twice as fast as previously believed possible.
The Isabella anomaly — indications of a large mass of cool, dehydrated material about 100 kilometers beneath central California — is in fact a surviving slab of the Farallon oceanic plate. Most of the Farallon plate was driven deep into the Earth’s mantle as the Pacific and North American plates began converging about 100 million years ago, eventually coming together to form the San Andreas fault.
PROVIDENCE, R.I. [Brown University] — Large chunks of an ancient tectonic plate that slid under North America millions of years ago are still present under parts of central California and Mexico, according to new research led by Brown University geophysicists. (more…)
Research May Also Help Determine Effects of Global Warming in the Region
With more than 40 million people living under exceptional drought conditions in East Africa, the ability to make accurate predictions of drought has never been more important. In the aftermath of widespread famine and a humanitarian crisis caused by the 2010-2011 drought in the Horn of Africa—possibly the worst drought in 60 years— researchers are striving to determine whether drying trends will continue.
While it is clear that El Niño can affect precipitation in this region of East Africa, very little is known about the drivers of long-term shifts in rainfall. However, new research described in the journal Nature helps explain the mechanisms at work behind historical patterns of aridity in Eastern Africa over many decades, and the findings may help improve future predictions of drought and food security in the region. (more…)
Study simulating pressures in mantle beneath the ocean floor shows that rocks can melt at depths up to 250 kilometers
Magma forms far deeper than geologists previously thought, according to new research results.
A team led by geologist Rajdeep Dasgupta of Rice University put very small samples of peridotite, rock derived from Earth’s mantle, under high pressures in a laboratory.
The scientists found that the rock can and does liquify, at least in small amounts, at pressures equivalent to those found as deep as 250 kilometers down in the mantle beneath the ocean floor. (more…)
Space weathering — a darkening of lunar surfaces by solar wind and metal nanoparticles from vaporized meteorites — appears to happen differently on Vesta, the largest body in the asteroid belt. The discovery, from NASA’s Dawn spacecraft, has planetary geologists returning to their lunar data for another look and further analysis.
PROVIDENCE, R.I. [Brown University] — The surface of the giant asteroid Vesta is weathering in a way that appears to be completely different from any other asteroid yet visited, according to new data recorded by NASA’s Dawn spacecraft. This new type of space weathering suggests that there’s something about Vesta — perhaps its mineral composition or its position in the solar system — that makes its surface environment fundamentally different from other asteroids studied thus far.
The new data are presented in a paper published Nov. 1, 2012, in the journal Nature. (more…)