Thomas Oldham

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Thomas Oldham (May 4, 1816, Dublin - July 17, 1878, Rugby) was a British geologist.

He discovered radiating fans shaped impressions in the town of Bray in 1840. He showed this to the English palaeontologist Edward Forbes, who named it Oldhamia after him. Forbes declared them to be bryozoans, however later workers ascribed it to other plants and animals. For a while these were considered the oldest fossils in the world.

He was educated at Trinity College and studied civil engineering at University of Edinburgh and also geology under Robert Jameson.

In 1838 he joined the ordnance survey in Ireland as a chief assistant under Joseph Ellison Portlock who was studying the geology of Londonderry and neighbourhood. Portlock wrote of him

“

whenever I have required his aid … I have found him possessed of the highest

intelligence and the most unbounded zeal

”

He became Curator to the Geological Society of Dublin, and in 1845 succeeded John Phillips, nephew of William Smith, in the Chair of Geology at Trinity College, Dublin.

He married Louisa Matilda Dixon of Liverpool in 1850. He resigned in November that year and took a position as the first Superintendent of the Geological Survey of India. He was to be the first of the Irish geologists to migrate to the sub-Continent. He was followed by his brother Charles, William King, son of the Professor of Geology at Queen’s College, Galway; Valentine Ball and more than 12 other geologists.

In India he oversaw a mapping program that focussed on coal bearing strata. The team of geologists made major discoveries. Henry Benedict Medlicott coined the term "Gondwana Series" in 1872. Oldham's son Richard Dixon Oldham distinguished three types of pressure produced by earthquakes: now known as P (compressional), S (shear), and L (Love)-waves, based on his observations made after the Great Assam Earthquake of 1897. Richard showed in 1906 the arrival patterns of waves and suggested that the core of the earth was liquid.

He also started the Paleontologia Indica, a series of memoirs on the fossils of India. For this work he recruited Ferdinand Stoliczka from Europe.

Oldham resigned from his position in India in 1876 on the grounds of poor health and retired to Rugby in England. He died on 17th July 1878.^[1]^[2]