The debate continues as to the cause of the more than 1,000 year-long cold interval known as the Younger Dryas. Falling on the heels of the Last Ice Age, or more correctly immediately after the two warm intervals known as the Bolling and Allerod interstadials, the Younger Dryas onset appears now to have started in as little time as one to three years. The climate shifted that suddenly from near present day warmth to near Ice Age cold. A second important feature to be noted is that apparently most of the planet was affected, and that the teleconnection between various parts of the planet was swift. This suggests strongly that the forcing mechanism resided in the atmosphere, rather than in the Ocean (where a much slower teleconnection would have been evident). The Younger Dryas however was very different from another alleged cosmic encounter, that of the great Cretaceous extinction event of approximately 65 million years ago. At this time, a huge bolide struck the Gulf of Mexico. Likely measuring as much as ten kilometres' across, the demise of the dinosaurs seems to have been assured.