Brown and James Sawkins arrived in Georgetown in 1867 and did some of their mapping and preparation of geological reports together and some in separate expeditions. Sawkins took a break from his work when Brown came upon Kaieteur Falls. In 1871, Brown discovered the New River, which he deemed the true source of the Courantyne. This gave rise to the New River Triangle border dispute between Suriname and British Guiana (now Guyana) was born. Barrington also visited Mount Roraima on the border between Brazil and Venezuela and was the first to describe the Tök-Wasen, a rock cliff formation located at the southern end of the mountain and suggested ascending it by balloon.