HILL, MAURICE NEVILLE

(b. Cambridge, England, 29 May 1919; d. Cambridge, 11 January 1966)

marine geophysics.]

Hill was the younger son of Archibald Vivian Hill, an eminent physiologist and Nobel laureate, and Margaret Keynes, sister of John Maynard Keynes, the Cambridge economist. When he was four, the family moved to Highgate, in North London. Much of Hill’s formal education was obtained as a day student at Highgate Junior and Senior Schools. At the age of eleven, however, after an undistinguished performance in the Junior School, he was sent to Avondale, a boarding school at Clifton, near Bristol, for two years. In the Senior School he did well at mathematics and physics, and displayed an aptitude for leadership.

Summer holidays during his boyhood were often spent at Ivybridge, near Plymouth, where Hill’s father worked at the Marine Biological Association’s (MBA) laboratory. From here Hill and a cousin. Richard Keynes, went to sea in the MBA’s ship Salpa; it was on these occasions that he began to acquire the skills of seamanship and a love of the sea. In the summer of 1938, on leaving school, Hill sailed to Bermuda on the Royal Society’s research ship Culver (a ninety-foot ketch) as second officer, an experience that probably turned his thoughts to oceanography.

In October 1938 Hill entered King’s College, Cambridge, to read natural sciences: specifically mathematics, physics, geology, and physiology, Following the outbreak of war, however, he did not return to Cambridge in the fall of 1939, applying instead for a technical post in the Royal Navy. Initially he was posted to H.M.S. Osprey, a shoreestablishment at Portland Bill devoted to antisubmarine warfare. After two years Hill was transferred to the sweeping division of the mine design department at Edinburgh, where he ultimately became a group leader and specialized in countermeasures to the German acoustic homing torpedo. While at Portland he regularly visited family friends who lived nearby and, through them, met his future wife, Philippa Pass. Married in 1944 at Edinburgh, they had three daughters and two sons.

In 1945 Hill returned to Cambridge and did a further year in physics. These two years as an undergraduate enabled him to qualify for a B.A. degree under wartime regulations. In the autumn of 1946 he started as a research student in the department of geodesy and geophysics at Cambridge. His Ph.D. project was to develop a method of making deepsea seismic observations in order to determine the thickness of the sediments and the nature of the rocks beneath them. Before the war a two-ship method for use in shallow water had been developed, initially by Maurice Ewing in the United States. Hill’s great achievement was to devise a single-ship method for use in deep (and shallow) water in which both shots and receivers were placed at comparatively shallow depths in the water column. In Hill’s method neutrally buoyant hydrophones were suspended beneath unmoored buoys and the signals transmitted by radio to the ship, where they were recorded. Thenew technique was first tested from a weather ship about three hundred miles (five hundred kilometers) west of Ireland and was a great success, seismic layers 1 (the sediments), 2, and 3 being recognized for the first time. A disadvantage of the method was that the radio range was limited to about nineteen miles (thirty kilometers) or so, and hence the Moho (or base of the crust) could not be detected. This deficiency was remedied in 1952 when, during work in the northeastern Atlantic and on the shelf around southwestern Britain, a second ship was used to fire shots and lines up to 62.5 miles (100 kilometers) and depths to the Moho were obtained.

In the late 1940’s Hill employed the method in the English Channel south of Plymouth, using an MBA vessel. This work provided some of the first evidence of the great thicknesses of Mesozoic and Tertiary sediments that characterize the shelf areas around the British Isles (in contrast with the land area) and provide such important hydrocarbon prospects. This work, together with the initial experiment west of Ireland, constituted the dissertation for Hill’s Ph.D., which was awarded early in 1951. In 1949 he had been elected a fellow of King’s College and appointed a research assistant in the department of geodesy and geophysics.

From 1950 to 1953 H.M.S. Challenger was on a round-the-world scientific cruise during which 48 Hill-type seismic lines were shot. Hill supervising the work personally in the northeastern Atlantic. These lines confirmed the existence of layer 2, which had been somewhat controversial, and revealed that in general layer 1, the sedimentary layer, is very thin, usually one hundred yards to about six-tenths of a mile (one hundred meters to one kilometer).

During the 1950’s Hill developed and became adept at deploying a number of other techniques of the new and rapidly expanding science of marine geology and geophysics: notably coring (of sediments) dredging (for hard rocks), and measurements of the geomagnetic field, using the newly developed protonprecession magnetometer. The importance of the latter two techniques in paving the way for the formulation of the Vine-Matthews hypothesis in 1963 cannot be overestimated. The hypothesis maintained that the anomalies in the geomagnetic field observed around midocean ridge crests could be explained in terms of seafloor spreading and reversals of the geomagnetic field. By 1967 this idea had led to confirmation of the theories of seafloor spreading and continental drift, and the formulation of the concept of plate tectonics. By the early 1960’s and as a result of Hill’s inspiration and leadership, a large and probably unique collection of rocks had been dredged by the Cambridge group and a considerable amount of magnetic data acquired from the ridges in the northern Atlantic and northwestern Indian oceans.

Thus two researchers in Hill;s group, D. H. Matthews and F. J. Vine, had access to new and unpublished information, in part magnetic data from the early phase of the International Indian Ocean Expedition (IIOE), in which the Cambridge group was enthusiastically participating, as well as the crucial knowledge that the measured remanent magnetization of the dredged basalts was very much greater than that of basalts extruded on land. However, as an experimentalist rather than as a theoretician, Hill did not have much time for grand theories such as those of continental drift and seafloor spreading, and there is very little speculation in his papers.

The very considerable contributions of the Cambridge group to the IIOE were presented at a Royal Society discussion meeting organized by Hill and held in November 1964. In the meantime, work in the northeastern Atlantic had not been neglected, and included a magnetic survey of the English Channel and Western Approaches that revealed a Hercynian structural grain trending at right angles to the shelf edge; the measurement of geomagnetic variations from moored buoys on the shelf that documented an unforeseen ocean-edge effect; studies of the median valley of the mid-Atlantic ridge to explore its continuity; and the integrated study of a number of seamounts.

Hill was one of the very small number of research group leaders who in the 1950’s developed the techniques of marine geology and geophysics that were to produce such startling results and profound implications for the whole of the earth sciences in the 1960’s. He was clearly a dedicated scientist and a born leader. He had a friendly nature and great charm, and was very popular with his research students and associates. He was greatly attached to King’s College, to which he contributed as a director of studies in natural sciences, a tutor, and a member of various committees. In 1962 he was elected fellow of the Royal Society; in 1963 he was awarded the Chree Medal of the Physical Society; and in 1965 he was made reader in marine geophysics at Cambridge. Despite all this, in the mid 1960’s he began to experience depression and to fell that in some way he was inadequate. In 1966, after a short spell in the hospital, he took his own life.

BIBLIOGRAPHY

A detailed account of the life and work of M . N. Hill is given by E. C Bullard in Biographical Memoirs of Fellows of the Royal Society, 13 (1967), 193–203. This includes a complete bibiography of Hill’s writings.

The first three volumes of The Sea (New York, 1963), for which he was general editor, were subtitled Ideas and Observations on Progress in the Study of the Seas. Volume IV , New Concepts of Sea Floor Evolution (New York, 1970), produced under the general editorship of Arthur E. Maxwell, was dedicated to Hill’s memory.

F. J. Vine