Taxonomy term

impact

Mineral in Chelyabinsk meteorite reveals past collision

A new analysis of fragments of the Chelyabinsk meteorite — which burst over Chelyabinsk, Russia, in February 2013 — reveals that its parent asteroid collided with another asteroid nearly 300 million years before it struck Earth.

20 Dec 2014

Acid oceans followed Chicxulub impact

Within days after the massive Chicxulub impact that ended the Cretaceous Period 65.5 million years ago, a deluge of acid rain may have turned Earth’s ocean surfaces into suddenly inhospitable homes for a multitude of microorganisms, ultimately pushing them to extinction, according to a new study.
 

21 Aug 2014

Africa's impact is one that even the dinosaurs would have seen coming

The crater left by the infamous Chicxulub asteroid responsible for finishing off the dinosaurs about 65 million years ago, was more than 19 kilometers deep and 177 kilometers in diameter. Those dimensions correspond to a huge energy release estimated at 100 teratons of TNT, but that’s puny compared to an impact that struck South Africa’s Barberton Greenstone Belt about 3.26 billion years ago. Now, researchers have estimated just how big that massive asteroid was and the catastrophic effect it might have had on Earth and its budding plate tectonic system.

14 Aug 2014

Ancient seawater found in Chesapeake Bay impact crater

The oldest seawater discovered to date — up to 145 million years old — has been found in deep sediments below the Chesapeake Bay impact crater. The highly saline water, a remnant from the ancient North Atlantic Ocean, was likely preserved when a 3-kilometer-wide bolide impacted the Delmarva Peninsula 35 million years ago, altering the region’s underlying structural geology, reported U.S. Geological Survey hydrologist Ward Sanford and colleagues in Nature.

19 Jul 2014

Lessons from the Russian meteor burst

Scientists can thank the high motor vehicle accident rate in the Russian city of Chelyabinsk for providing the most stunning videos ever recorded of a meteor burst. Because of the many traffic accidents in that city, dashboard cameras abound, constantly recording everything in front of a car — the road, other vehicles, pedestrians, and, incidentally, the sky.

At about 9:20 a.m. on Feb. 15, 2013, many of those cameras recorded the explosion of a large meteor 23 kilometers above the city. As was widely reported at the time, the air blast shattered windows, and meteorite fragments rained down in and around Chelyabinsk, causing damage to some 7,000 buildings and sending about 1,600 people to hospitals. Although no one was killed, it marks “the first ever asteroid impact disaster in human history,” according to Clark R. Chapman of the Southwest Research Institute (SwRI) Planetary Science Directorate in Boulder, Colo., who presented research on the event at the annual meeting of the American Geophysical Union (AGU) in San, Francisco, Calif., last December.

18 May 2014

Iowa impact crater confirmed

An airborne geophysical survey mapping mineral resources in the Midwest has confirmed that a 470-million-year-old impact crater nearly five times the size of Barringer (Meteor) Crater in Arizona lies buried several hundred meters beneath the town of Decorah, Iowa.

07 Jul 2013

Santa Fe impact crater discovery: A series of fortunate events

In the ancient pink and orange hills of the Sangre de Cristo Mountains, Thornton “Tim” McElvain, a retired petroleum geologist, leads me over a concrete highway barrier to a towering granite road cut. McElvain steps onto a rock pile and points to a meter-long block of granite, the freshest offering to fall from the rock face. One side of the block tapers roughly to the shape of a cone, with grooves coming together to form a point.

“This is the best shatter cone example I’ve seen here,” McElvain says.

07 Oct 2011

The impact at El'gygytgyn crater

Moment of impact: As the asteroid hits the ground with a velocity of several tens of kilometers per second, a shock wave is generated that penetrates radially into the ground and compresses the rocks.

Contact/compression stage
Christian Koeberl, University of Vienna

 

 

 

 

 

 

 

 

20 Jul 2010

Do impacts trigger extinctions? Impact theory still controversial

The revolution started with a bang in 1980. For some, this revolution became a religion, even an orthodoxy. The true believers became proselytes and began to see signs supporting their viewpoint everywhere. But each time the proselytes claimed to have found yet another example in support of their “religion,” naysayers and doubters emerged. Two sides formed, each loudly castigating and questioning their opponents.

This back-and-forth ideological debate describes both the historical and still-ongoing struggle over a purported cause of mass extinctions: the meteor impact theory.

23 Jun 2010

Travels in Geology: Chesapeake Bay, from impact craters to executive orders

The lower part of the Chesapeake Bay offers more than crab cakes and boating. Today, the bay is central to one of country’s largest environmental campaigns. But an excursion around the Virginian coasts provides an amazing peek into the mid-Atlantic region’s rich geological, environmental and cultural history, spanning impact events, glaciation, early colonial settlements and modern struggles with pollution and rising sea level.

06 Oct 2009

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