The Surveys of Brown and Sawkins
In 1857, gold was discovered in the area of the Yuruari River, a small tributary of the upper Cuyuni. Since the British Guiana government was not too sure if the Yuruari was located east of the "Schomburgk Line", the Governor, Philip Wodehouse, sent two expeditions to the area to verify its location. However, only one team, led by Sir William Holmes, managed to reach the upper Cuyuni, but the report it submitted could not determine the exact position of the river relative to the "Schomburgk Line".
Ten years later, after there were more gold discoveries in the upper Cuyuni and the upper Mazaruni Rivers, the British government appointed two British geologists, Barrington Brown and James Sawkins to survey the interior of the colony. Shortly after their arrival in Georgetown in November 1867, they travelled with their survey team to the Pomeroon District to begin their work, which included mapping and preparing geological reports. On completing the surveys there, they moved on to survey the area from the Waini River to the Barima and the Barama Rivers. From there they went to the upper Cuyuni and the Mazaruni.
After this first round of their surveys, the two geologists split up to undertake separate expeditions in 1868. Sawkins did a survey of the Demerara River while Brown mapped the Essequibo River and parts of the Rupununi savannahs. The two met in the Rupununi area in late 1869, but then parted again to survey the areas near to the border with Brazil. Brown went towards the source of the Essequibo River and mapped two of its tributaries, the Rewa and Kwitaro Rivers. Meanwhile, Sawkins mapped the Takutu River and then joined up with Brown in December 1869.
On their return to Georgetown, Sawkins decided to take a break from the surveying task. However, Brown continued in 1870 to explore and map the interior of Essequibo, and eventually arrived at the Kaieteur Falls on the Potaro River on the 24 April. He became the first person of European origin to see these falls.
He then travelled to Georgetown to complete his report, but in July he went back to Kaieteur to measure the height of the falls. His calculation showed a total height of 822 feet made up of two drops, the main part being 741 feet, and a second drop of 81 feet over the rocks at the bottom of the main fall.
In late 1870 and during part of 1871, Brown and Sawkins teamed up again to survey the Corentyne, Berbice and Mazaruni Rivers. On the completion of their work in those areas, they departed for Britain in 1871.
In the course of their expeditions, the two geologists traversed some of the territory mapped by Robert Schomburgk more than two decades before, and they were able at times to make corrections on some of the information he had gathered. They also prepared reports on the geology of the areas they surveyed and the work they completed provided a wealth of information on the geography and geology of the country.