Authored by Jon Mercer in Science
Published on 01-12-2009
Scientists have long wondered why about 12,900 years ago an abrupt cooling of the Earth took place. Now they have discovered clues that could mean that one or more meteors could have slammed into North America. This would explain the extinction of mammoths, saber tooth tigers and possibly the first human’s that inhabited the Americas.
Although this hypothesis has been regarded skeptically, researchers have reported that they have discovered a thin layer of microscopic diamonds in rocks across America and Europe. These microscopic layers of diamonds are a residue that is known to be produced when meteors hit the surface of a planet, or Earth in this case.
Geologists say they have found evidence of strike residue from meteors in over thirty sites from California in the west, and as far east as Germany. A meteor strike would also explain the cause of the 1,300-year cold spell, known as Younger Dryas, that scientists say began when a sudden rush of fresh water swelled from a giant lake in central Canada into the North Atlantic Ocean. Normally, warm water currents flow northward in the Atlantic toward Greenland and Europe, then cools and sinks, returning south in the deep ocean. Scientists say the less dense fresh water blocked the sinking of the cold, salty water in the North Atlantic, disrupting currents.
This sudden change in currents caused the temperature to drop; this has been known by scientists for years, and now researchers say that the reason is most probably a meteor strike. Upon examining each of the sites where the diamond residue was found, scientists have determined that the diamond layer in the rocks correlates exactly with the date of the proposed meteor impact.
Other evidence of a meteor strike impact in North America is the elevated levels of the element iridium. Still, there are skeptics that refute the idea of a meteor strike; the number one argument against a meteor impact in North America is the fact that there is no obvious crater. Even though proponents of the meteor theory say that the impact zone could have been an area with a thick layer of ice, the opponents of the theory say that it still should have still left a gigantic hole in the ground beneath the ice.
If the meteor theory is true, the hypothesis could explain the disappearance of Ice-Age mammals like the Wooly Mammoth. This would also discredit the idea that the mammals were hunted to extinction by early humans.