Geologic Timeline By calesjul Sep 22, 1926 Cambrian Period Period: Sep 22, 1926 to Sep 22, 1953 Paleozoic Era 570-500 MYA Period: Sep 22, 1926 to Sep 22, 1937 Cambrian Period Sep 22, 1937 Ordovician Period Period: Sep 22, 1937 to Sep 22, 1944 Ordovician Period Sep 22, 1944 Silurian Period Period: Oct 24, 1944 to Oct 24, 1953 Silurian Period Sep 22, 1953 Devonian Period