At the closing of the Pleistocene era around 13,000 geezerhood ago , North America lost most of its megafauna — including mastodons , giant land sloths , sabre - toothed khat , and brusque - faced bear . Some investigator imagine the slew extinction was because of climatic change or maybe even humans ; others think it was the abrupt environmental changes leave from a comet collision with Earth that head to theYounger Dryasperiod of world-wide cooling just a twosome centuries later .
In anew studypublished in theJournal of Geology , researchers fence for the latter hypothesis . They indicate that the same cosmic impact that took out the Pleistocene megafauna may have also make midget diamonds across at least three continents around 12,800 years ago .
Cosmic hit such as these produce a type of textile called nanodiamonds . To day of the month , the only other layer where more than one nanodiamond has been found is the Cretaceous - third limit ( now known as the Cretaceous - Paleogene boundary ) from 65 million years ago , famous for the experimental extinction of dinosaurs .
Now , a large international team working at 32 site in 11 nation have found an abundance of nanodiamonds distribute over 50 million square km across the Northern Hemisphere at the Younger Dryas bound ( YBD)—a carbon copy - rich layer that look as a fragile dim line just a few meters below the aerofoil .
“ We once and for all have identified a thin bed over three continents , particularly in North America and Western Europe , that contain a rich gathering of nanodiamonds , the yield of which can be explain only by cosmic impact,”saysJames Kennett from the University of California , Santa Barbara . The strewnfield of this major cosmic impact insure at least 10 percentage of the planet .
The nanodiamonds in the YDB were found in several var. , including cubic ( the sort used in jewellery ) and hexagonal crystals . These unlike type are the result of orotund variations in temperature , pressure , and oxygen tie in with the chaos of an impingement . “ These are exotic condition that occur together to produce the diamond from terrestrial carbon , ” Kennett says in anews liberation . “ The diamonds did not go far with the incoming meteorite or comet , ” he add up . A cubic nanodiamond from Murray Springs , Arizona , is render to the rightfulness .
The team also found many other YDB textile , some of which organize at temperature in excess of 2,200 degree Celsius and that “ could not have resulted from wildfires , volcanism or meteoritical flux density , but only from cosmic impact,”Kennett explains .
image : UC Santa Barbara
