Considered "one of the last true geological polymaths",[1] Sollas worked in a number of areas including the study of sponges, brachiopods and petrological research, and during his lifetime published 180 papers and wrote three books.

[3] After becoming an Associate of the Royal School of Mines he competed with William Garnett for chemistry scholarships at St. John's College, Cambridge; they were both accepted.

[3] At Cambridge Sollas was taught by Thomas George Bonney, who persuaded him to switch to geology, which he did, gaining First Class Honours in the Natural Sciences Tripos in 1873.

[6] At Oxford his main contribution was significantly expanding the Geology department, appointing new demonstrators and lecturers and employing his own daughters as unpaid research assistants.

This investigation followed the work on the structure and distribution of coral reefs conducted by Charles Darwin in the Pacific.

[4] Sollas's research was over a wide area; during his lifetime he published over 180 papers and three books,[4] and as well as his geological and zoological studies became an expert in anthropology.

His first major paper was on the granite of Leinster, where he conducted a detailed chemical analysis of the rock and invented the diffusion column to assist in this.

[10] In 1896 he travelled to the Pacific Ocean to investigate the formation of the Funafuti coral atoll, drawing inconclusive results.

[4] In 1905 he published the collection of essays The Age of the Earth, and in 1911 an anthropological work Ancient Hunters and their Modern Representatives.

[2] This method was destructive, but made it possible to study previously unknown internal structures of fossil animals such as ichthyosaurs,[13] and dicynodonts.