Cyfnod
- 1603?-1659 1 canlyniadau
- 1813-1855 1 canlyniadau
- 1938-1945 1 canlyniadau
- 1973-1993 1 canlyniadau
- 1975-1979 1 canlyniadau
- 1976-2002 1 canlyniadau
- Cambrian 1 canlyniadau
- Cenozoic 1 canlyniadau
- Precambrian 1 canlyniadau
- To 1505 1 canlyniadau
- Transfer of Sovereignty from Great Britain, 1997 1 canlyniadau