Taxonomy term

june 2017

Mineral Resource of the Month: Fluorspar

Fluorite occurs in a variety of geological environments deposited under a wide range of chemical and physical conditions, but commercial sources are primarily hydrothermal. The most common deposits occur as veins, mantos (replacement strata-bound orebodies), or replacement deposits. Other important deposits include stockworks and fillings in shattered zones, carbonatite and alkalic rock complexes, residual concentrations resulting from the weathering of primary deposits, and recoverable gangue in base metal deposits.
25 May 2017

Timing of famed "Millennium Eruption" pinpointed

Changbaishan Volcano in northeastern China, on the border with North Korea (where it’s known as Mount Paektu), is steeped in superstition, having produced devastating eruptions several times in recorded history. Legends that a massive eruption in the 10th century led to the downfall of a regional empire have now been refuted, however, thanks to a new analysis of a fossilized tree killed by the eruption that dates the eruption to after the kingdom fell.

25 May 2017

Geologic Column: Is it aged or mature?

The authors cast a poetic eye on the language used to discuss aging in geoscience and engineering.
24 May 2017

Meteorites did not spark Ordovician biodiversification

During the Ordovician Period, roughly 470 million years ago, an asteroid the size of a small moon collided with another rocky object in the belt between Mars and Jupiter, shattering the asteroid into billions of pieces. Fragments from the epic collision still occasionally fall to Earth today, making up a large share of the meteorites recovered. But in the immediate wake of the Ordovician event, many pieces rained down on the planet, settling on the surface and in layers of rock forming at the time. In a new study, researchers studying some of these meteorite-rich layers have refined the timescale for the collision. The results bring into question a proposed link between the meteorite bombardment and an evolutionary uptick known as the Great Ordovician Biodiversification Event (GOBE).

23 May 2017

When and how did plate tectonics begin on Earth?

Earth’s surface is a shifting puzzle of plates that collide and diverge, generating earthquakes, fueling volcanoes, opening ocean basins and raising mountain ranges. But when and how did this process — unique in our solar system as far as we know — begin? 
22 May 2017

Are North Atlantic storm tracks shifting south?

As the Arctic warms, decreasing temperature differences between the Arctic and the lower latitudes may push North Atlantic storm systems south. The factors that influence storm tracks are complicated, however, and the accuracy of models predicting future storm tracks is uncertain. The results of a new study, in which researchers looked at changes in Atlantic storm tracks over the past 4,000 years, could improve the accuracy of predictive models and help Europe prepare for shifting storm patterns.

19 May 2017

"Blob"-related warming contributed to Pacific Northwest ozone spike

In June 2015, instruments on Oregon’s Mount Bachelor recorded mean ozone for the month at 56 parts per billion, more than 20 percent higher than the average level for the 11 years prior. Other stations around the West noted similarly high readings, puzzling scientists over the cause of the rise. In a new study in Geophysical Research Letters, researchers describe a confluence of meteorological conditions that appear to have driven the phenomenon.

18 May 2017

How often should we expect volcanic ash clouds over Europe?

In 2010, an ash cloud from an eruption at Iceland’s Eyjafjallajökull Volcano led to the most disruptive shutdown of North Atlantic and European airspace in aviation history. Given the high level of activity of Iceland’s more than two dozen active volcanoes, how often are such events to be expected? A new study comparing volcanic ash records over the last 1,000 years suggests that fallout over Europe may be more common than previously anticipated.

17 May 2017

Tibetan Plateau populated long before advent of agriculture

Due to the harsh living conditions of the Tibetan Plateau — which has an average elevation over 4,500 meters — archaeologists have long assumed that people didn’t live in the Himalayan high country until after the adoption of agriculture in this region of the world, about 3,600 years ago. But a new study of a trove of handprints and footprints found around a fossilized mud spring in Tibet is suggesting that people may have lived here as early as 13,000 years ago.

16 May 2017

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