Reginald Daly was educated at the University of Toronto, where geologist
A.P. Coleman persuaded him away from teaching mathematics and into Earth Sciences. He obtained his PhD at
Harvard, and did postgraduate work in Germany and France. 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. Daly was president of
The Geological Society of America in 1932. For the Boundary Commission, working in six field seasons, Daly mapped the border from the Pacific Ocean to the Great Plains, a rugged swath long and wide – an area of about . He documented the geology alone, but had the help of one field assistant and numerous wranglers and porters. He collected 1,500 rock specimens and made 960 thin sections, using a German polishing technique he learnt as a student. The project also included 1,300 photographs, dozens of lake soundings, stratigraphic and structural mapping, petrology, and morphology. 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. This work along the
49th parallel led him to formulate a theory of the origins of
igneous rocks, and later publish his seminal work
Igneous Rocks and Their Origin in 1914. According to Daly's biographer, James Natland, Daly was an early proponent of
Arthur Holmes and
Alfred Wegener's
continental drift theory. 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. Daly's theory on continental displacement was based partly on the idea that after the Moon was ejected from the Earth, continental movement was an inevitable part of rebalancing the planet; he also suggested that continental material accruing near oceans eventually slips, and forces continents to creep along. 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. Daly also proposed the
impact theory of lunar creation in 1946, which countered two prevailing notions: George Darwin's hypothesis that the Moon spun out of the primordial Earth due to centrifugal force; and, another fashionable theory that the Moon was a captured wayward asteroid. Daly applied Newtonian physics to make his point, which was later validated. 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. ==Family==