May 23, 2014

Laid to rest – Colin Forbes (1922-2014)

A geologically distinctive cobblestone in the Old Court, Clare College in the University of Cambridge has recently been engraved with the initials CLF and relaid in the courtyard. The initials belong to the late Dr Colin Forbes, onetime curator of the University’s Sedgwick Museum.
Category: 2014
Posted by: Sarah

Colin was a Cambridge undergraduate, who served in World War II (1942- 1947), firstly as a sapper in the ranks of the Royal Engineers, then rising to become a motor transport officer and temporary captain in the Bombay sappers and miners. After demobilization in 1947, he was a student in Clare College, taking a degree in geology in 1949, followed by a PhD on the ‘Carboniferous Stratigraphy and Palaeontology of Central Vetspitsbergen’ in 1953. The following year he was appointed as Assistant Curator in the Sedgwick Museum until 1967, when he was promoted to Curator. He took early retirement in 1983 in order to devote more time to his role as a director of the Cambridge Water Company.

It was as a student that Colin first recognized the singularity of one particular cobble amongst the hundreds of other in Clare Old Court and he always claimed that it was his ‘favourite feature of Old Court’.
To a well trained geologist the ‘CLF’ cobble is instantly recognizable as an igneous rock known as a rhomb porphyry, and what is more, it is a kind of rhomb porphyry that only occurs in the Oslo region of southern Norway.

So-called ‘exotic’ cobbles like this occur in surface ‘Drift’ deposits all over the lowlands of the east of Britain, dumped by the vast ice sheets that flowed out from the Scandinavian highlands during the Quaternary ice ages over the last two million years or so. Recognition and identification of the geological sources of such exotic rocks provided key evidence in the 19th century debate on whether ‘Drift’ deposits had a glacial origin or were the products of the Noachian Flood.

The rhomb porphyry of the Oslo region is a particularly attractive rock with large pale coloured and rhomb-shaped crystals of anorthoclase feldspar set amongst a much darker and fine grained mineral matrix. These rocks were originally erupted as thick and extensive lava flows over southern Norway some 350 million years ago in early Carboniferous times.

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