Civil War, 1861-1865 27
Precambrian 11
19th century 8
Cambrian 7
1837-1865 6
1884-1972 6
1822-1885 4
Paleozoic 4
1835-1910 3
1865-1950 3
20th century 3
Carboniferous 3
Pennsylvanian 3
1734-1820 2
1767-1838 2
1770-1838 2
1854-1861 2
1929 2
21st century 2
Cretaceous 2
Mesozoic 2
Mississippian 2
Ordovician 2
Quaternary 2
Tertiary 2
-1855 1
1750-1815 1
1752-1818 1
1777-1846 1
1809-1865 1
1809-1867 1
1815-1875 1
1818-1861 1
1830-1902 1
1831-1891 1
1836-1902 1
1847-1882 1
1856-1903 1
1864?-1943 1
1867-1957 1
1867-1959 1
1870-1945 1
1877-1964 1
18th century 1
1901-1988 1
1904-1977 1
1929-2007 1
1933-1945 1
1945-1953 1
1945-1989 1
1951- 1
1967-2015 1
1986- 1
1991- 1
1996-2014 1
Archaean 1
Cenozoic 1
Devonian 1
Jurassic 1
Permian 1
Proterozoic 1
To 1803 1
To 1865 1