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

GA Le Bel (fl1893) wrote concerning his receipt of the Davy medal from the Royal Society.

George Alexander Louis Lebour (1847-1918) wrote regarding the thermal conductivity of rocks, particularly work done by Edward Forbes (1815-1854) and Sir William Thomson (1824-1907)

Arthur Lennox (fl1869-1875) wrote on a number of professional and social matters, including arranging to visit Geikie, mentioning his own travels in Europe and arranging an introduction by Geikie to the publisher Macmillan. He was to be proposed by the Duke of Richmond for the post of Inspector of Science and Art Schools, if he could provide suitable testimonials, and asked Geikie for one. By 1875 he was writing from the Council on Education at the South Kensington Museum. He also discussed an article he had published in the Times and problems relating to it.

J Peter Lesley (1819-1903) was the state geologist in charge of the Second Geological Survey of Pennsylvannia and corresponded with Geikie while in this post. After a breakdown in 1893, his wife, Susan, replied to Geikie's letters, thanking him for his support. Early letters concern Geikie's visit to Lesley in 1879. Later letters introduce Henry Carvill Lewis (1853-1888) and WJA Price (fl1886) to Geikie. He also refelcts on the nature of science, religion and life itself.

A Michel Lévy wrote about geological mapping in France

Sir Joseph Norman Lockyer (1836-1920) was secretary to the Royal Commission on Scientific Instruction and the Advancement of Science. He wrote to Geikie in connection with this position, as a member of the Science and Art Department, South Kensington, where he moved after 1875 and as founder and editor of Nature.

Sir Oliver Joseph Lodge (1851-1940) was the first principal of the University of Birmingham and he wrote to Geikie about social matters, a lecture by Geikie and an attempt by the Earl of Portsmouth to join the Royal Society.