Sir Archibald Geikie corresponded with a large number of people both socially and professionally. These letters are mixed together and the series is alphabetically arranged. The majority of correspondence in this series concerns minor matters of professional interaction such as requests or thanks for copies of geological papers.

A large amount of the correspondence deals with the details of publishing geological paper, books and maps, such as acceptances of articles, arrangements for acknowledgments and thanks for complimentary copies. Examples are the 6 letters from John Hutton Balfour which deal with the details of publishing Geikie's work in the Philosophical Transactions of the Royal Society of Edinburgh, and 2 from the map publisher John George Bartholomew concerning details of the publication of some geological maps.

A number of letters are from junior employees of the Geological Survey of Great Britain who are undertaking field work, reporting on their progress. These include George Barrow, H Arnold Bemrose and FJ Bennett.

Other letters are from amateur geologists reporting on discoveries or asking for assistance. These include the missionary Richard Baron, who undertook the first geological survey of Madagascar and the Rev PB Brodie who undertook palaeontological studies in the southern counties of England.