Reginald Aldworth Daly

Who was Reginald Aldworth Daly?

Reginald Aldworth Daly was a Canadian geologist. He was educated at the University of Toronto, where geologist A.P. Coleman persuaded him away from teaching mathematics and into Earth Sciences. His PhD was attained at Harvard, with postgraduate work in Germany and France. After working as a field geologist for the Canadian International Boundary Commission, he was a professor and head of the Department of Geology at Harvard University from 1912 until 1942.

For the Boundary Commission, working in six field seasons, Daly mapped the border from the Pacific Ocean to the Great Plains, a rugged swath 400 miles long and 5 to 10 miles wide – an area of about 2,500 square miles. 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.