Era
Precambrian
28
Pennsylvanian
20
Mississippian
14
Cambrian
12
From 570 million to 5 billion years ago
12
Paleozoic
12
Ordovician
10
Quaternary
9
Carboniferous
7
From 2 million years ago
5
From 280 to 310 million years ago
5
Permian
5
19th century
4
Devonian
4
From 310 to 345 million years ago
4
Pleistocene
4
From 230 to 310 million years ago
3
1811-1812
2
Cenozoic
2
From 280 to 345 million years ago
2
From 345 to 405 million years ago
2
Mesozoic
2
Proterozoic
2
1784-1864
1
1793-1864
1
1797-1861
1
1800-1899
1
1807-1886
1
1829-1887
1
1872-1912
1
1874
1
1966
1
19th centuyr
1
Early works to 1800
1
From 10 thousand to 2 million years ago
1
From 230 million to 5 billion years ago
1
From 230 to 570 million years ago
1
From 280 to 500 million years ago
1
From 310 to 405 million years ago
1
From 310 to 570 million years ago
1
From 405 to 425 million years ago
1
From 425 million to 2 billion years ago
1
From 425 to 500 million years ago
1
From 425 to 570 million years ago
1
From 500 to 570 million years ago
1
From 65 to 570 million years ago
1
Silurian
1
fl. 1797-1825
1