William Noel Benson was born at Penge, Surrey, England, on 26 December 1885, the son of William Benson, of independent means, and his wife, Emma Elizabeth Mather. Shortly after their son's birth the couple moved to Australia: to Melbourne, then Hobart. William and his two younger sisters attended the Friends' School, of which their father was a trustee. Noel developed an interest in geology under his father’s guidance.
After a year at university in Hobart, Noel Benson removed to Sydney in 1904 intending to study physics. However, the teaching of T. W. Edgeworth David persuaded him to concentrate on geology. By the end of 1907 he had published his first paper and gained first-class honours in geology. He then took up a lectureship in mineralogy and petrology at the University of Adelaide in 1908. The next two years saw him demonstrating at the University of Sydney while mapping a large area in New South Wales.
Following the award of a scholarship, he set out for England and the University of Cambridge in 1911 taking with him nearly half a ton of rocks from the New England area of New South Wales. He left Cambridge with a BA, having gained valuable petrographic experience under Alfred Harker. The results of his New England work were published in nine parts from 1913, culminating in a benchmark paper in 1918 on the origin of serpentine. He returned to Sydney in 1914, where he was a research fellow for the Linnean Society of New South Wales, then in 1915–16 an assistant lecturer in geology at the University of Sydney, from whom he received a DSc in 1916.
Benson was appointed professor of geology in the University of Otago in December 1916. On 8 December 1923, at his parents’ home in Killara, New South Wales, Benson married Gertrude Helen Rawson, professor of home science at the University of Otago. She was born in Bradford, Yorkshire, England, on 25 January 1886 (and registered as Gertrude Ellen), the daughter of Agnes Annie Cragg and her husband, Joseph Cordingley Rawson, a cotton-spinner. Helen attended high school in Bradford and Newnham College, University of Cambridge; she completed the natural science tripos, but as women were not then allowed to graduate, received her BSc only in 1919. After gaining a postgraduate diploma in household and social science from King's College, London, she was appointed in 1911 to the newly opened School of Home Science in the University of Otago as a lecturer in chemistry and household and social economics. She and Professor Winifred Boys-Smith had to overcome prejudice against the new department and cater for increased student numbers by providing improved facilities and a hostel for accommodation.
After the retirement of Boys-Smith in 1920, Helen Rawson became professor of home science and dean of the Faculty of Home Science. She made better provision for the teaching of practical subjects, including the building of laboratories, and reorganised the school's courses. In 1919 she studied in Canada and the United States. On her return to New Zealand in 1920 she founded the New Zealand branch of the Federation of University Women, becoming its first president. Following her marriage, Helen Benson resigned from her university position and became increasingly involved in community activities.
Noel Benson was the only member of the geology department until the appointment in February 1926 of F. J. Turner as lecturer and assistant. As a newcomer with considerable research experience, Benson was able to see New Zealand geology with fresh eyes, and his critical review of recent advances published in 1921 was another benchmark paper.
Noel Benson had identified old erosion surfaces in eastern Australia and his attention was caught by the same phenomena in Otago. Work on the geology of east Otago, begun in the early 1920s, involved mapping a pre-volcanic erosion surface as well as the Cretaceous peneplain; Benson had an unusual skill for representing landforms in field sketches. He also investigated the petrogenesis of the volcanic rocks of east Otago; some of this work was done with F. J. Turner. An important summary of petrographic provinces appeared in 1941 along with the first of six descriptive papers (a comprehensive memoir remained unpublished at his death). Two important projects interrupted the east Otago work: studies of fossil-bearing rocks in southern Fiordland (1934–38) and in the Cobb Valley, Nelson (1956). Members of other geology departments took part in these well-planned investigations.
Some of Benson's work had an immediate practical application. Mapping within Dunedin involved investigating new road- and rail-cuts and commercial and domestic excavations. Studies of land-mass movement, especially in urban areas, led to statements on engineering hazards of local rock types.
Helen Benson lectured on international affairs to the WEA for many years, and took a practical interest in the plight of refugees who came to New Zealand in the 1930s. She was a member of the Senate of the University of New Zealand from 1939 to 1948. She was also closely involved with the National Council of Women of New Zealand. In 1933 she strongly supported the adoption of a motion that criticised the lack of financial relief for unemployed women and in 1937 was partly responsible for the council's taking a sympathetic attitude towards abortion in some circumstances. She represented the NCW at an International Council of Women meeting in Paris in 1934. Elected president in 1940, she resigned shortly afterwards, possibly because her pacifism made it difficult for her to hold the position.
Helen and Noel Benson's was 'an ideal partnership', with the couple sharing ideas and religious beliefs. Both were active members of the Society of Friends and both served as clerk of the Dunedin meeting. They represented New Zealand at the Pan-Pacific Science Congress in Japan in 1925 and then travelled extensively there and in Asia. An interest in international affairs led to Noel Benson's becoming secretary of the New Zealand branch of the Institute of Pacific Relations, which he represented at a conference in Paris in 1934.
The post-war years saw Noel Benson, now venerable, inspiring students as he had always done. True, there were occasions when he appeared before his students wearing an overcoat instead of a gown, but it was a genuinely admiring, grateful, crowded class which made a presentation to him at his last lecture in 1949. He had received many honours for his excellence in research. He was a fellow of the Royal Society of London, the Royal Society of New Zealand, of geological societies in many countries and of other professional bodies. He received numerous medals for his work and was awarded an honorary DSc by the University of New Zealand. Before his election as emeritus professor in 1951, the University of Otago Council appointed him William Evans research professor for 1950. During what was to be a short retirement, he and Helen travelled to England.
Helen Benson was 'tactful, sensitive and gracious'; Noel was noted for his keen sense of humour. Their house, Dunottar, was a place of genteel hospitality visited and enjoyed by generations of geology students. They had no children. Following a period of indifferent health, Noel died in Dunedin on 20 August 1957; Helen died at Dunedin on 20 February 1964.