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John Hannes Callomon 1928-2010

John Callomon
John Callomon was one of the world's leading authorities on Jurassic ammonites. One of the most significant developments in their study in the past 50 years was the recognition of sexual dimorphism within them, with females normally many times larger than the puny males. This was the independent work of two men: one the Polish geologist Henryk Makowski (1900-1997); the other, John Callomon. 

Callomon was born in Berlin in 1928, the only child of Hans Callomon and Gertrude, née Steigmann. His father was an engineer with Allgemeine Electricitats Gesellschaft (AEG). Having seen what Hitler was creating, the family moved as refugees to England in 1937 when John was nine years old. AEG had connections with GEC in Birmingham, where the family settled and were approached by locals befriending those fleeing persecution. Among them were Horace and Julie Sanders of Erdington.

Horace, a metallurgical engineer, was an equally enthusiastic geologist. According to Sanders, "John soaked up knowledge like a sponge" and, through Sanders, now 100 years old, Callomon started his lifelong fascinations with both engineering and geology. Callomon went to King Edward's School in Birmingham (1940-46), where his interests in science were awakened amid the wonderful stocks of the local library. He won an open scholarship to St John's College, Oxford, to study natural sciences, graduating with a first in chemistry in 1950. Then followed doctoral studies under Dr Harold Warris Thompson in infrared spectroscopy at Oxford.

Next came post-doctoral research in Ottawa under the Canadian spectroscopist Gerhard Herzberg, another refugee from Nazism, who won the Nobel Prize for Chemistry in 1971.This was one of the world's great laboratories in the field of molecular physics, where Callomon recorded how "he felt at ease in a world in which distances were a million times smaller, and events a thousand million times shorter than those within any direct human experience".

In 1957, after another post-doctoral fellowship at University College London, Callomon was appointed to a lectureship there, rising through the hierarchy until he was awarded a chair in chemistry in 1981, retiring in 1993. Before his arrival at Oxford, Callomon's taste for geology was whetted by Horace Sanders on West Midlands tandem excursions. This was extended at Oxford, where Callomon undertook detailed investigations of local Jurassic rocks, under the influence of the doyen of the study of Jurassic rocks, William Joscelyn Arkell, whose book The Geology of Oxford appeared in 1947. In the decades since, Callomon has been an equal leader in geology, across a number of different fields, as in chemistry.

He pioneered the recognition of sexual dimorphism in ammonites and revised the Treatise in Invertebrate Paleontology on them. He made major contributions to stratigraphic knowledge of (mainly) Middle and Upper Jurassic rocks all round the world, but particularly in their boreal (northern) realm. His Greenland work, with Tove Birkelund, was rewarded with the Steno Medal by the Danish Geological Society in 1993, its centenary year. Callomon brought his sanity and clarity of expression to the complex world of stratigraphic precision in geology (in the process reminding us how incomplete the geological record can be) and to the vexed questions of stratigraphic and zoological nomenclature.

Callomon was no amateur. He is better regarded as a vital "outsider" to geology, which has been enormously improved by his many contributions. His paper to the Royal Institution in 1984 on "The Measurement of Geological Time", stemming from his earlier training in exact science, deserves to be a classic. As for his revolutionary work on sexual dimorphism in ammonites, this became a victim of peer review, when all his supposed peers proved unequal to the task. Callomon certainly has priority of discovery. He had already named, and separated, macroconchs from microconchs (the large and small sexes noted above) in a paper communicated to the Royal Society in 1955,and outlined his mature ideas in 1957to the Geologists' Association. He was ready to publish his major paper in 1958 (while Makowski's similar work was submitted for editing only in December 1961 and published in July 1963).

But Callomon's mould-breaking paper had finally to be published in the Transactions of the Leicester Literary and Philosophical Society, late in 1963 (by early September), after rejection by Biological Reviews, Journal of Zoology, Palaeontology and Journal of Paleontology; all four of which claimed, anonymously, that it was “not worth publishing”. Callomon became a magnificent reviewer himself and rejected the whole idea of anonymity. He is survived by Esther, his wife of 56 years, and their three sons.

John Callomon, chemist and geologist, was born on 7 April 1928. He died on 1 April 2010 aged 81.

Hugh Torrens