Maurice Ewing

American oceanographer (1906–1974)

Ewing was born at Lockney in Texas and educated at the Rice Institute, Houston, obtaining his PhD in 1931. He taught at Lehigh University, Pennsylvania, from 1934 until moving in 1944 to Columbia University, New York, where he organized the new Lamont Geological Observatory into one of the most important research institutions in the world.

Ewing pioneered seismic techniques to obtain basic data on the ocean floors. He was able to establish that the Earth's crust below the oceans is only about 3–5 miles (5–8 km) thick while the corresponding continental crust averages 25 miles (40 km).

Although the Mid-Atlantic Ridge had been discovered when cables were laid across the Atlantic, its dimensions were unsuspected. In 1956 Ewing and his colleagues were able to show that the ridge constituted a mountain range extending throughout the oceans of the world and was some 40,000 miles (64,000 km) long. In 1957, working with Marie Tharp and Bruce Heezen, he revealed that the ridge was divided by a central rift, which was in places twice as deep and wide as the Grand Canyon.

His group found that the oceanic sediment, expected to be about 10,000 feet (3000 m) thick, was nonexistent on or within about 30 miles (50 km) of the ridge. Beyond this it had a thickness of about 130 feet (40 m) – much less than the depth of the corresponding continental sediment. All this seemed to be consistent with the new sea-floor spreading hypothesis of Harry H. Hess. Ewing was however reluctant to support it until Frederick Vine and Drummond H. Matthews showed how the magnetic reversals discovered by B. Brunhes in 1909 could be used to test the theory.

Ewing also proposed, with William Donn, a mechanism to explain the periodic ice ages. If the Arctic waters were icefree and open to warm currents this source of water vapor would produce greater accumulations of snowfall. This would increase the Earth's reflectivity and reduce the amount of solar radiation absorbed. Temperatures would fall and glaciers move south, but with the freezing of the Arctic seas the supply of water vapor would be cut off and the ice sheets would retreat. This would cause an increase in solar radiation absorbed and the cycle would begin again. No hard evidence has yet been found in support of the theory.

The American oceanographer William Maurice Ewing (1906-1974) was a leader in modern earth science research, especially in the applications of geophysics to oceanography.

Maurice Ewing was born in Lockney, Texas, on May 12, 1906. He was the fourth of 10 children of Floyd Ford Ewing, a farmer and hardware merchant, and Hope Hamilton Ewing. His older siblings died at very young ages, so he grew up as the eldest of seven. He preferred to be known as Maurice, rather than William. His parents stressed the importance of education, and Ewing studied diligently and received a scholarship to college. Working at night to support himself, he received his bachelor's (1926), master's (1927), and doctoral (1931) degrees from Rice Institute in Houston. He first majored in electrical engineering and later switched to mathematics and physics, which he found more interesting. One physicist, H. A. Wilson, had a major influence on Ewing. Wilson held a weekly series at Rice attended by many prestigious scientists who made a big impression on Ewing.

Won Geological Grant

Ewing was instructor in physics at the University of Pittsburgh from 1929 to 1930. He moved to Lehigh University as instructor of physics in 1930, becoming assistant professor in 1936 and associate professor of geology in 1940. Probably the most important event of his professional life occurred in 1935, when a committee of distinguished geologists asked if he would undertake the task of applying the techniques of geophysics to the ocean areas. He jumped at the chance and with their support obtained a grant from the Geological Society of America for a classic refraction study of the structure of the Continental Shelf off the East Coast of the United States. This was quickly followed by a successful gravity-measuring cruise on the Barracuda, using the newly developed gravity pendulum apparatus introduced by F.A. Vening Meinesz.

With the aid of some of his students, Ewing built ocean-bottom cameras and automatic apparatus for making seismic refraction measurements at the bottom of the deep-ocean basins. Several seismic measurements had been successfully made by the time World War II broke out. In September 1940 the National Defense Research Committee (NDRC) was being discussed by leaders of the scientific community as an important adjunct to the military in the event of U.S. involvement in the war. Early recognizing the importance and probable results of the war, Ewing obtained a leave of absence from Lehigh University and moved to the Woods Hole Oceanographic Institution (WHOI) to commence defense research. Without recompense, until the NDRC was officially formed in January 1941, he and his former students wrote Sound Transmission in Sea Water, the standard manual throughout the war and long after for understanding and predicting the results of sound-echo ranging. They also redesigned the bathythermograph from a bulky, tedious, and unreliable instrument to one capable of obtaining temperature-depth information to depths of 900 feet from ships underway at speeds up to 20 knots. It was adopted by the Navy and was the standard instrument with only minor changes for over 20 years.

During the war Ewing was the leading physicist at WHOI in the development and application of underwater photography and underwater sound for use by the Navy. It was in this period that he introduced the long-range sound transmission studies, resulting in the SOFAR system and providing the basic ideas behind the Navy's long-range surveillance and detection systems.

Lamont-Doherty Geological Observatory

In 1946 Ewing initiated an extensive program of geophysical training for graduate students at Columbia University. He was promoted to professor in 1947 and was made Higgins Professor of Geology in 1949. That year Columbia made available the former Thomas W. Lamont estate for the use of the geophysics group to undertake studies in earthquake seismology. The Lamont Geological Observatory was formed as a part of the department of geology with Ewing named director. In 1961 the observatory was changed to a research institute within the university to promote research with other university departments; in 1969 the name was changed to the Lamont-Doherty Geological Observatory.

From 1947 to his retirement Ewing continued his work at Columbia and WHOI. During his career, he carried out an extensive research career authoring or coauthoring 280 papers and three books. He received 10 honorary degrees from universities in four countries and 26 medals and awards from institutions and scientific societies of eight nations. He died at the age of 67 in 1974. His wife, Harriet, collected many of his private papers and donated them to the University of Texas. They are housed at the Harry Ransom Humanities Research Center in Austin.

Further Reading

Ewing's contributions to oceanography are discussed in Robert C. Cowen, Frontiers of the Sea: The Story of Oceanographic Exploration (1963); and Warren E. Yasso, Oceanography: A Study of Inner Space (1965). Additional material on Ewing is in David Robert Bates, ed., The Planet Earth (1957; rev. ed. 1964); William S. von Arx, An Introduction to Physical Oceanography (1962); and Günter Dietrich, General Oceanography: An Introduction (trans. 1963).

Further information on Ewing can be found in Frederic L. Holmes, ed., Dictionary of Scientific Biography, vol. 17 (1970; rev. ed. 1990), and Roy Porter, ed., The Biographical Dictionary of Scientists (1994).

Ewing, William Maurice, 1906-74, American oceanographer and geologist, b. Lackney, Tex., grad. Rice Institute, now Rice Univ. (B.S., 1926; M.A., 1927; Ph.D., 1931). He taught physics and geology at the Univ. of Pittsburgh and Lehigh Univ. and was a research associate at Woods Hole Oceanographic Institution in Massachusetts. In 1935, he took the first seismic measurements in open seas (Atlantic Basin at the Mid-Atlantic Ridge and in the Mediterranean and Norwegian Seas) and developed a seismometer that has become a standard. He proposed that earthquakes are associated with central oceanic rifts and suggested that seafloor spreading may be worldwide and episodic in nature. In 1939, he took the first deep-sea photos. In 1944 he joined the faculty of Columbia Univ. and in 1949 founded and became the first director of Columbia's Lamont Geological Observatory (now Lamont-Doherty Geological Observatory) at Palisades, N.Y. Lamont-Doherty now holds one of the world's largest collection of deep-sea cores because of Ewing's many oceanic explorations. In 1960, Ewing became the first recipient of the Vetlesen Prize, an award given by the Vetlesen Foundation to honor leaders in the earth sciences.

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