[2] He is known for the 1959 eponymous Folk classification of sedimentary rocks, which, with some minor modifications, is still in use today.
[3] His Ph.D. thesis Petrography and petrology of the Lower Ordovician Beekmantown carbonate rocks in the vicinity of State College, Pennsylvania was supervised by Paul Dimitri Krynine (1902–1964).
In autumn 1951, Robert Folk, with his wife and son, moved to Houston, Texas, where he had employment as a sedimentary geology working for Gulf Oil Research.
Folk was appointed in September 1952 as an assistant professor in the geology department of the University of Texas at Austin.
[6] In 1988 he was employed as senior research scientist at the Bureau of Economic Geology, University of Texas at Austin.
[5] His book Petrology of Sedimentary Rocks, based on his course notes for graduate students, first appeared in 1957, went through 6 editions, and was revised periodically until 1980.
[5] Folk believed that he had discovered, in the early 1990s, evidence of nannobacteria in rock from hot springs of Viterbo in the Lazio region of Italy.
F. McBride Petrography Fund to sponsor a rock sample identification contest held annually for U.T.