Era
Pleistocene
28
From 10 thousand to 2 million years ago
14
Ordovician
12
Pennsylvanian
10
Mississippian
9
Quaternary
8
Devonian
7
From 425 to 500 million years ago
6
Cretaceous
5
Carboniferous
4
From 280 to 345 million years ago
4
Proterozoic
4
Paleozoic
3
Precambrian
3
19th century
2
From 2 million years ago
2
From 280 to 310 million years ago
2
From 345 to 405 million years ago
2
From 570 million to 2 billion years ago
2
From 570 million to 5 billion years ago
2
Holocene
2
Silurian
2
1852
1
1984
1
Cambrian
1
From 10 thousand to 25 million years ago
1
From 2 to 140 million years ago
1
From 310 to 345 million years ago
1
From 500 to 570 million years ago
1
From 65 to 140 million years ago
1
Jurassic
1
Miocene
1
Quaternaire
1
Tertiary
1