In 1850, Thomas Oldham, a 34-year-old geologist based in Dublin, married Louisa Matilda Dixon of Liverpool. By then, he had already earned recognition in the field of geology. In his 20s, Oldham made a notable discovery of unusual radiating and fan-shaped impressions in shales, which were later named Oldhamia in his honour by the renowned English palaeontologist Edward Forbes.
By that time, as he was preparing to get married, Oldham had made considerable strides in his career. He had already become the Curator of the Geological Society of Dublin and was serving as Chair of Geology at Trinity College, Dublin. Despite receiving two salaries, he was uncertain about his financial stability after marriage. This uncertainty eventually led him to resign from his positions in Dublin and accept an opportunity in faraway India.
The offer Oldham took was from the English East India Company to be the first Superintendent of the Geological Survey of India—a department that was non-existent and that he had to build from the ground up. On March 4, 1851, Oldham arrived in Calcutta and officially took charge the next day, marking the formal establishment of the Geological Survey of India. As GSI celebrates its 175th anniversary on Tuesday, THE WEEK looks back at the journey of its founding father, Thomas Oldham.
Visionary in work
The GSI was set up primarily to find coal deposits for the Railways. However, Oldham chalked out a plan to expand the area of work of the department. Notably, Oldham triggered a migration of smart Irish geologists to the subcontinent. There are records suggesting that at least 12 prominent Irish geologists, including Oldham’s own brother, Charles, followed his path to India.
As the head of GSI, Oldham initiated an ambitious mapping program that focused on coal-bearing strata. A massive surveying programme in Bengal and Central India had been undertaken by him and as part of it, coalfields had been given special attention.
The group of Irish geologists who were working under Oldham also made significant discoveries in India which continue to have bearings even in modern-day geology.
For instance, geologist Henry Benedict Medlicott, along with his brother Joseph G. Medlicott, determined the separation of the Cambrian Vindhyan region from the Gondwana—an ancient supercontinent that incorporated present-day South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica.
The brothers in fact mapped the line separating the Vindhyan and Gondwana, and Henry is credited with the coining of the term Gondwana, which broke up around 180 million years ago and led to the formation of modern continents and ocean basins, shaping Earth's current geography.
Under Oldham’s leadership, another crucial initiative to be launched was a monumental series on Indian palaeontology, published as Paleontologia Indica. This series aimed to document and study fossils found in India, and to support this effort, Oldham brought Moravian palaeontologist Ferdinand Stoliczka from Europe.
Paleontologia Indica became a cornerstone of paleontological research in India, making significant contributions to global palaeontology. It also served as a key resource for understanding India's rich Gondwana fossil flora and fauna.
The history of dinosaur discoveries in India began in 1828—long before Oldham’s arrival—when Captain W.H. Sleeman, a British officer in the Bengal Army, unearthed fossilised bones, including a vertebra. These bones initially passed through the hands of amateur palaeontologists before reaching James Prinsep, a British numismatist and archaeologist known for his contributions to India's historiography. In 1862, Thomas Oldham became the custodian of these valuable fossils, which were later handed over to Hugh Falconer.
In 1868, Falconer identified them as reptilian vertebrae. This work ultimately contributed to the first formal description of a dinosaur from the Indian subcontinent by Richard Lydekker in 1877—45 years after Sleeman's initial discovery.
In 1876, Oldham resigned from his Indian position because of poor health and retired to Rugby in England where he died on 17th July 1878.
Two decades after his death, Oldham’s son Richard Dixon Oldham became the first to clearly identify the separate arrivals of primary (P), secondary (S), and surface waves on seismograms. This differentiation enhanced the understanding of seismic wave propagation and the internal structure of the Earth. He made this discovery in his comprehensive report on the 1897 Assam earthquake, which became valuable data that advanced the field of seismology.
In 1906, Richard further demonstrated that seismic waves can be used to study the internal structure of the earth—and he established that the earth has a large core. Later studies have shown that in the 1897 Assam earthquake, the Shillong Plateau moved upward along two blind faults. One of these faults has been named the Oldham fault.
Over the past 175 years, the GSI has evolved significantly. And, today it plays a crucial role in geological mapping, mineral exploration, disaster studies, and geoscientific research—contributions that have been instrumental in driving India's industrial and economic growth.
And, each year, India honours the Irishman Oldham who initiated the transformation of the Geological Survey of India (GSI) from a modest coal exploration initiative to an institution in geoscience innovation.
