Reginald Aldworth Daly | |
|---|---|
 | |
| Born | May 19, 1871 |
| Died | September 19, 1957 (1957-09-20) (aged 86) |
| Alma mater | Victoria University, Toronto (B.A., 1891; S.B., 1892) Harvard University (Ph.D., 1896) |
| Awards | Hayden Memorial Geological Award (1932) Penrose Medal (1935) Wollaston Medal (1942) William Bowie Medal (1946) |
| Scientific career | |
| Fields | Geology |
| Institutions | Harvard University Massachusetts Institute of Technology |
| Doctoral advisor | John E. Wolff |
| Doctoral students | Norman L. Bowen[1] |
Reginald Aldworth Daly (May 19, 1871 – September 19, 1957) was a Canadiangeologist. He is best known for being one of the first proponents of thegiant-impact hypothesis of the formation of theMoon.
Reginald Daly was educated at the University of Toronto, where geologistA.P. Coleman persuaded him away from teaching mathematics and into Earth Sciences. He obtained his PhD atHarvard, and did postgraduate work in Germany and France. After working as a field geologist for theInternational Boundary Commission, he was a professor, and headed the Department of Geology at Harvard University from 1912 until 1942. Daly was president ofThe Geological Society of America in 1932.[2]
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 (640 km) long and 5 to 10 miles (8.0 to 16.1 km) wide – an area of about 2,500 square miles (6,500 km2). 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.[3] In 1912, he filed his final report with theGeological Survey of Canada, a massive 3-volume tome he calledNorth America Cordillera: Forty-Ninth Parallel.[4] This work along the49th parallel led him to formulate a theory of the origins ofigneous rocks, and later publish his seminal workIgneous Rocks and Their Origin in 1914.
According to Daly's biographer, James Natland, Daly was an early proponent ofArthur Holmes andAlfred Wegener'scontinental drift theory.[5] Daly summarized his ideas in his 1926 book,Our Mobile Earth, which included on the title page small print adopted fromGalileo: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 inStrength and Structure of the Earth, in 1940, where Daly anticipated aspects ofplate tectonics, including introduction of a "mesospheric shell" and a slippery vitreous basaltic substratum.
Daly also proposed theimpact 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 geologistNorman L. Bowen, who, based on experiments and observations of natural rocks, summarized the order of crystallization of common silicate minerals from typicalbasalticmagma undergoingfractional crystallization, now known asBowen's reaction series.
In 1903, Daly married Louise Porter Haskell, daughter ofAlexander Cheves Haskell and Alice Van Yeveren, and elder sister ofMary Elizabeth Haskell. After their marriage, Louise accompanied Daly on his travels, and in the field, as an assistant. She did much of the work in preparing and editing his manuscripts and books, and Daly's 1914 book on 'Igneous Rocks and their Origin'[6] is dedicated to her; his "inspiring fellow worker".[7]
In 1909, Daly was elected a member of theAmerican Academy of Arts and Sciences.[8] He was elected to theAmerican Philosophical Society in 1913 and the United StatesNational Academy of Sciences in 1925.[9][10] Daly was awarded thePenrose Medal in 1935, theWollaston Medal in 1942[11] and theWilliam Bowie Medal in 1946. In 1950 he became foreign member of theRoyal Netherlands Academy of Arts and Sciences.[12] The potassium zirconium silicate mineraldalyite[13] andcraters onMars[14] and theMoon are named in his honor. His Cambridge, Massachusetts, house (theReginald A. Daly House) is now aNational Historic Landmark.
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