Roderick E. Dumbleton matriculated through the University of the Cape of Good Hope in 1891 and passed the university's examination for the Certificate of proficiency in the theory of land surveying in 1893. He was admitted as a land surveyor in the Cape of Good Hope in 1895.
Dumbleton excavated a cave near the Touwsrivier, which runs into the sea at Wildernis on the Cape south coast. His account of the excavation was published in the Cape Town Diocesan College and School Magazine in 1892. The article includes the first description of a hafted stone implement found in South Africa, as well as a description of associated skeletal material. The paper was soon difficult to obtain, but was quoted extensively by L. Péringuey* in his monograph, "The stone age of South Africa as represented in the collection of the South African Museum" (Annals of the South African Museum, 1911, Vol. 8). The hafted implement may have first aroused Péringuey's interest in South African prehistory. He exhibited it at a meeting of the South African Philosophical Society in September 1892, but did not identify the finder. H.W.R. Marloth* analysed the gum with which the implement was attached to its stick and found that it was a fine resin containing chalk and starch grains.
Dumbleton resided in George, Western Cape, and married Annie Duthie Bowker on 12 December 1899. They had one daughter.