George Leith, teacher and later legal agent, conveyancer and sworn translator, was a son of George Gordon Leith and his wife Ann, born Rodger. In 1879 he married Sarah ("Sally") Clark Scott of Greenock, Scotland, with whom he had eight children. They came to the Cape Colony that same year because George was suffering from tuberculosis. He taught at Riversdal (1881-1885) and Mossel Bay. After some years he wrote A metrical outline of Cape history and chronology (Cape Town, 1885, 20 p.), of which a fourth edition was published in 1894. By May 1886 he was teaching in Knysna, where his fifth child and eldest son, George E.G. Leith, who later became a well-known architect, was born. During that year the family seems to have moved to Burgersdorp. Here he met Dr D.R. Kannemeyer*, who showed him rock paintings near the town and aroused his interest in the prehistory of South Africa.
Kannemeyer prompted him to excavate the large shelter at Cape St Blaze, Mossel Bay, in order to test the views of Dr W.G. Atherstone*, expressed in 1871, that the shell deposits in the cave were middens deposited by humans. The excavation, in the form of a small cutting, took place around 1888 and conclusively proved the human origin of the shell deposits. It also provided the first good account of Middle Stone Age artefacts found below the shell middens, later named the Mossel Bay industry. In 1889 Leith settled in Pretoria as a legal agent, where he continued his archaeological pursuits. By 1893 he was considered to have accumulated a valuable collection and had "recently read an interesting paper on the subject of stone implements before the Philosophical Society at Pretoria" (Jones, 1893). Very little is known about this society. In October 1892 State Secretary Leyds referred to it as the "Natuurhistorisch Gezelschap" (Natural History Association), of which Leith was the chairman, when recommending to President Kruger that he be appointed on the first management committee (Raad van Curatoren) of the State Museum (later the Transvaal Museum, now the Ditsong National Museum of Natural History). The appointment was approved and he was still a member of the committee by 1898.
Leith published a description of his excavation at Cape St Blaize only in 1898, in an important paper titled "Caves, shell-mounds and stone implements of south Africa" (Journal of the Royal Anthropological Institute, Vol. 28, pp. 258-274). The importance of this paper lies in its wide coverage, describing also artefacts of the Stellenbosch type that he found on the Mossel Bay Flats; his finds in the Burgersdorp Cave in the Stormberg and Bat's Cave at East London; shell middens between Cape St Blaize and Great Brak River, at Port Elizabeth, at the Buffalo River mouth, and at the mouth of the Mzimkulu River, Natal; artefacts from the Springbok Flats in the Transvaal and from Pretoria; and his find of "eoliths" in the gravels of the Apies River near Pretoria. His paper also addressed the problem of differentiating between naturally and humanly flaked pieces of stone, and described some spherical chipped rock balls from the Zoutpansberg, Transvaal, and Winburg in the Free State.
Leith sold some of his "eoliths" and Early Stone Age artefacts from Pretoria, material from his Cave St Blaize excavation and artefacts from the Mossel Bay Flats to W.A. Sturge, who later bequeathed the collection to the British Museum (Natural History). In 1898 he donated a collection of 28 "eoliths" and 29 "palaeolithic" implements from the river gravels at Pretoria to the South African Museum in Cape Town. That same year he became a member of the South African Philosophical Society. In 1901 the Transvaal Museum was in the process of acquiring "a unique collection of Bushman implements" from Leith. He died of tuberculosis.