What scientists can tell from a tree-ring calendar that goes back 4,500 years

National Geographic (@NatGeo) tweetou às 7:06 PM on seg, Abr 29, 2013: What scientists can tell from a tree-ring calendar that goes back 4,500 years: http://t.co/C3TfPulgTZ (https://twitter.com/NatGeo/status/328933375211622400) Adquira o aplicativo oficial do Twitter em https://twitter.com/download