Time Periods

Cambrian 570m-500m

Sep 30, 1921

Ordorvacine 500m-435m

Sep 30, 1932

Silunan 435m-395m

Sep 30, 1939

Devonian 395m-345m

Sep 30, 1948

Carboniferus 345m-280m

Sep 30, 1959

Permain 280m-225m

Sep 30, 1969

triassic 225m-195m

Sep 30, 1974

Jurassic 195m-136m

Sep 30, 1984

Cretaceous 136m-65m

Sep 30, 1997

Tertiary 65m-1.8m

Sep 30, 2008

Quaternary 1.8m-present

Sep 30, 2011