David Duckworth Fraser junior was the son of Reverend David Duckworth Fraser*, educationist and amateur geologist, and his wife Margaret, born Taylor. He presumably came to the Cape with his father in 1873. In about 1887, while they were living in Bedford, father and son made a study of the local geology and donated a case of rock specimens from around Bedford to the Albany Museum in Grahamstown. They also collected shell and plant fossils in the area and these too were donated to the museum. Like his father, David junior was a foundation member of the South African Geological Association, which was formed in Grahamstown in June 1888. During the founding meeting Reverend Fraser read a paper on their geological study of the Division of Bedford. At the next annual meeting of the association in Cape Town in July 1889 David junior, described as "a young and enterprising geologist", read a paper in which he concluded that the Trigonia bearing strata of the Zwartkops and Sundays River beds were of Neocomian (Lower Cretaceous) age, rather than Jurassic as had previously been thought. This conclusion had also been reached some years earlier by the German geologist M. Neumayr.
Fraser moved to Port Elizabeth with his father at the beginning of 1891. They both joined the Eastern Province Naturalists' Society (Port Elizabeth, 1884-1923) in February that year. In 1893 one or both of them donated Glossoptera and other fossil plants from the lower Beaufort beds at Bedford to the British Museum (Natural History). David junior remained interested in palaeontology for a number of years, for in 1899 he arranged and named the fossils from the Uitenhage beds and Bokkeveld beds in the Port Elizabeth Museum.