Doctor Who Through the Decades: 1970's

Can you identify an event that happened in the Whoniverse for each year of the 1970's?

1970 A young girl regenerates into who will later be known as 'Mels'.

1971 Sarah Jane Smith attends a tour of the Sistine Chapel.

1972
UNIT acquire the Tunguska Scroll, sealing it away in the Black Archive.

1973 Iris Wildthyme is exiled to Earth.

1974 The Fourth Doctor encounters the K1 Robot.

1975 The head of a Cyberman is found in the London Sewers, and later ends up in Van Staten's museum.

1976 The Fourth Doctor encounters the Zygons in Scotland.

1977 The Fourth Doctor encounters the Fendahl.

1978 The Fourth Doctor and Romana I encounter Cailleach.

1979 The Fourth Doctor and Romana II visit Paris.