Taxonomy term

impact

Minerals deformed by meteorites reveal age of impact

Researchers have discovered a new way to determine when a meteorite hit Earth, a technique that could not only help scientists date ancient meteorite strikes but also determine when planetary crusts first formed.

03 Oct 2017

Platinum may point to impact theory for Younger Dryas

Some large meteorite strikes leave obvious craters on Earth’s surface, while others that hit water or ice or explode in the air may only leave subtle markers in the soil, such as exotic minerals or elevated levels of rare elements like platinum or iridium. In a new study, researchers report spikes of platinum in sediments at archaeological sites across North America, offering new evidence, they suggest, of a major meteorite strike about 12,800 years ago, just before the onset of a global cold period known as the Younger Dryas. The lack of a telltale crater dating to this time, however, has left scientists debating for years whether an impact actually occurred and what, if any, role it had in setting off the cold snap and affecting some of Earth’s human and animal populations.

21 Jun 2017

Mystery impact may have kicked off dramatic warming event

About 56 million years ago, the planet warmed rapidly in a mysterious event known as the Paleocene-Eocene Thermal Maximum (PETM). Researchers recently discovered evidence in the rock record from around the same time that points to an extraterrestrial impactor striking Earth, but whether the two events are related is yet to be determined.

06 Feb 2017

Impact or eruptions: Are both to blame in the great end-Cretaceous whodunit?

Few episodes in geologic history are as widely recognized — and debated — as the end-Cretaceous extinction. For several decades, the Chicxulub impact has been the primary suspect. But new research suggests the impact wasn’t solely responsible for the extinctions; widespread volcanism in India seemed to play a role as well.

25 Jan 2016

Meteorites might have created Earth’s earliest continents

Massive meteorite impacts on Earth are destructive events, gouging enormous craters in the crust and raining debris over the planet’s surface. But such huge impacts may have also created some of its earliest continental kernels, called cratons, during Archean times.
 
08 Jan 2016

Ancient asteroids boiled Earth's oceans

The asteroid that wiped out the remaining dinosaurs — save for the avian variety — 66 million years ago was roughly 10 kilometers wide. Long before that, however, early Earth was bombarded by many larger impactors, which pulverized Earth’s surface time and again. Now, a new study published in Geology suggests that two asteroids, dating to Archean times and estimated to be 50 to 100 kilometers in diameter, released enough energy to boil the oceans and reduce sea level by as much as 100 meters or more.
 
10 Oct 2015

Geologic Column: The 'impact factor' of potholes

Bumpily driving along one day last spring on a road that had been battered by a snowy winter in the Northeast and Mid-Atlantic left the author pondering potholes — from a geologic perspective.

07 Oct 2015

Benchmarks: July 22,1960: Mineral discovery ends Meteor Crater debate

In 1923, Daniel Moreau Barringer stood on the edge of a vast bowl-shaped depression in the Arizona desert, watching a drill rig bore into the floor of the crater. Barringer had spent more than two decades exploring the massive hole, which lies on the Colorado Plateau 65 kilometers east of Flagstaff, Ariz. And although he had sunk dozens of drill holes, collected scores of samples, and carefully mapped the piles of talus that draped its concave walls, Barringer still hadn’t found what he was looking for, and he was getting nervous.
 
22 Jul 2015

Giant bolide hit South Africa 2.5 billion years ago

Some of the oldest scraps of continental crust on Earth cling to the southern tip of Africa and the western edge of Australia. In both places, geologists have found rock layers rich in tiny particles called spherules. Scientists think spherules form when meteorites strike the planet, vaporizing surface rocks that then condense into small droplets, blanketing the surrounding landscape. Now, research published in Geology confirms the extraterrestrial origin of a 2.5-billion-year-old layer of spherules in South Africa, which scientists say was produced by a bolide at least as large as the one that doomed the dinosaurs.
 
06 Jun 2015

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

Pages