Scientists have long believed that a comet exploded over the North America continent 12,900 years ago, causing a mass cooling of the planet and a catastrophic dying off among mammals. The period, known as the Younger Dryas, lasted around 1,000 years and is recorded in various marine sediments and ice cores. Now even more evidence has been discovered to support this theory. Science Daily reports that nanodiamonds revealed in a Greenland ice sheet shows that a comet may have struck the area long ago.

Nanodiamonds, which can be seen only through a microscope, originate after a detonation. Their newly discovered existence in the Greenland ice sheet is exciting for experts. James Kennett is professor emeritus in the Department of Earth Science at UC Santa Barbara who worked on the discovery.

As Kennett told Science Daily, “There is a layer in the ice with a great abundance of diamonds…this is the first such discrete layer of diamonds ever found in glacial ice anywhere on Earth, including the huge polar ice sheets and the alpine glaciers. The diamonds are so tiny that they can only be observed with special, highly magnifying microscopes. They number in the trillions.” This discovery comes on the heels of another nanodiamond revelation in a layer of sediment on Santa Rosa Island on the California coast.

The Younger Dryas period occurred around 12,900 years ago and is known for its massive die-off of people and animals. Around this time, the Clovis people of North America lived off the mammoths in the area. But the Clovis, as well as mammoths, horses, camels and the saber-tooth cats, all seemed to disappear from the Earth around this time. High concentrations of iridium, an element association with meteors, have been found at Clovis sites. High levels of metal and magnetic spherules have been found inside the bones of some mammoths. Further, massive wildfires swept the North American continent at this time.

Hopes are that this latest discover of nanodiamonds will shed more light on this mysterious time in the Earth’s history.

For further reading:

New evidence of nanodiamonds in Greenland's ice sheet
Existence supports theory that a comet decimated North America around 13,000 years ago.