Era
Cretaceous
186
Tertiary
109
Precambrian
78
Eocene
69
Cenozoic
68
Permian
67
Miocene
65
Paleozoic
62
Mississippian
50
Pennsylvanian
48
Jurassic
46
Mesozoic
45
Ordovician
45
Quaternary
44
Devonian
43
Pleistocene
40
Triassic
40
Proterozoic
36
Oligocene
32
Cambrian
25
Pliocene
24
Silurian
22
Paleocene
20
Carboniferous
19
Holocene
15
Archaean
12
Neogene
9
1834-1902
3
19th century
3
Paleogene
3
1904-1967
2
20th century
2
1770-1838
1
1774-1809
1
17th century
1
1805-1885
1
1809-1865
1
1818-1891
1
1864-1945
1
1887-1986
1
18th century
1
1928-
1
1938-
1
1945-
1
1960
1
Civil War, 1861-1865
1
Pre-Quaternary
1