 Studies suggest correlations between the Younger Dryas and a supernova that exploded within the constellation of Vela approximately around the same time, leaving behind what is now known as the Vela supernova remnant.Researchers who studied effects of nearby supernovae on earth uncovered suggestive correlating evidence during the Younger Dryas, including depletion of the ozone layer, increased UV exposure, nitrogen changes on the Earth's surface and in the troposphere, evidence of global cooling, changes in 14C and 10Be in ice cores, a thin layer (about 30 cm) of “black mats”, and many extinctions that may have been caused by the explosion of the Vela supernova.While no cause is determined for the extinction of many species, a combination of some climatic change or being hunted by humans is suggested as a cause.