After working as a field geologist for the International Boundary Commission, he was a professor, and headed the Department of Geology at Harvard University from 1912 until 1942.

[3] In 1912, he filed his final report with the Geological Survey of Canada, a massive 3-volume tome he called North America Cordillera: Forty-Ninth Parallel.

[5] Daly summarized his ideas in his 1926 book, Our Mobile Earth, which included on the title page small print adopted from Galileo: E pur si muove.

He expanded this notion in Strength and Structure of the Earth, in 1940, where Daly anticipated aspects of plate tectonics, including introduction of a "mesospheric shell" and a slippery vitreous basaltic substratum.

His doctoral students included the Canadian geologist Norman L. Bowen, who, based on experiments and observations of natural rocks, summarized the order of crystallization of common silicate minerals from typical basaltic magma undergoing fractional crystallization, now known as Bowen's reaction series.