Sir Archibald Geikie corresponded with a number of people both socially and professionally. This sub-series includes the following correspondents:

Alexander Henry Green (1832-1906) corresponded with Sir Archibald Geikie about positions he was applying for (he became professor of geology at Yorkshire College, Leeds) as well as on more general professional and social matters. In one he included a letter possibly from Sir Charles Lyell. John Walter Gregory (1864-1932) wrote to Geikie regarding his applications for the geology chair at the University of Oxford and the professorship of geology at the University of Melbourne.

Geikie corresponded with Sir Richard John Griffith (1784-1878), geologist and mining engineer to the Royal Dublin Society, on a number of professional matters, including details of Griffith's work in Ireland.

Correspondence from Henry Brougham Guppy (1854-1926) deals largely to his own work on coral reefs in the Solomon Islands and a related donation to the museum in Jermyn Street. Valentine Ball, Director of the Science and Art Museum in Dublin, wrote concerning that museum.

Letters from Edward Townley Hardman (1845-1887) concerned reports of his work, surveying and mapping the area around Kimberley, Western Australia. He named several features in that area after Geikie.