His ability at once attracted the notice of his chief, Sir Roderick Murchison, with whom he formed a lifelong friendship, and whose biographer he subsequently became.

In 1863 he published an important essay "On the Phenomena of the Glacial Drift of Scotland", in Transactions of the Geological Society of Glasgow, in which the effects of ice action in that country were for the first time clearly and connectedly delineated.

[2] In 1865 Geikie's Scenery of Scotland (3rd edition, 1901) was published, which was, he claimed, the first attempt to elucidate in some detail the history of the topography of a country.

[4] At this time the Edinburgh school of geologists, prominent among them Sir Andrew Ramsay, with his Physical Geology and Geography of Great Britain were maintaining the supreme importance of denudation in the configuration of land surfaces, and particularly the erosion of valleys by the action of running water.

Geikie's book, based on extensive personal knowledge of the country, was an able contribution to the doctrines of the Edinburgh school, of which he himself soon began to rank as one of the leaders.

A feature of his tenure of office was the impetus given to microscopic petrography, a branch of geology to which he had devoted special study, by a splendid collection of thin sections of British rocks.

The results of his further research were given in an essay entitled "The History of Volcanic Action during the Tertiary Period in the British Isles," in Transactions of the Royal Society of Edinburgh (1888).

His book Founders of Geology consists of the inaugural course of lectures (founded by Mrs George Huntington Williams) at Johns Hopkins University, Baltimore, delivered in 1897.

[6] He was the editor of The Geological Structure of the North-West Highlands of Scotland (1907, His Majesty's Stationery Office), written by B. N. Peach, John Horne, William Gunn (1837–1902), C. T. Clough, L. W. Hinxman, and J. H. H.