Time Periods By kcbeale Sep 30, 1921 Cambrian 570m-500m Sep 30, 1932 Ordorvacine 500m-435m Sep 30, 1939 Silunan 435m-395m Sep 30, 1948 Devonian 395m-345m Sep 30, 1959 Carboniferus 345m-280m Sep 30, 1969 Permain 280m-225m Sep 30, 1974 triassic 225m-195m Sep 30, 1984 Jurassic 195m-136m Sep 30, 1997 Cretaceous 136m-65m Sep 30, 2008 Tertiary 65m-1.8m Sep 30, 2011 Quaternary 1.8m-present
