A critical analysis of the geologic literature of ancient deltaic sediments reveals that there has been a noticeable increase in the number of significant papers since 1959. During the 80-year period prior to 1959 only 8 papers on ancient deltas appeared in print. These early contributions were by Gilbert (1885, 1890), Barrell (1912), Barton (1930), Twenhofel (1932), Busch (1953), Pepper et al. (1954), and Nanz (1954). During a 5-year period beginning in 1959, 12 significant publications on ancient deltaic deposits of the United States, England, Scotland, and Brazil appeared in print. In the past 8 years an additional 14 papers have been published. Thus, during the 13-year period since 1959, the publication of significant delta papers has been at the rate of about 2 paper per year. A review of the literature on the geology of modern deltas also is quite revealing. Prior to World War II only 7 papers on modern deltas of North America were published. These were: Johnson (1920, 1921) on the Fraser delta of northwest Canada; Trowbridge (1930), Russell (1936), and Russell and Russell (1939) on the Mississippi delta; and Sykes (1937) and McKee (1939) on the Colorado delta of southern California and Mexico. Following World War II there was a steady increase in the studies of modern deltas beginning with Fisk's work on the Mississippi delta (Fisk, 1944, 1947, 1952, 1954, 1955, 1958, 1961). Other important studies of modern deltas were: Moore and Scruton (1957), Scruton (1960), and Welder (1959) on the Mississippi delta, and Kruit (1955), Van Straaten (1961), and Lajaaij and Kopstein (1964) on the Rhone delta of southern France. Post-World War II research on the Mississippi and Rhone deltas and other studies of modern deltas provided reliable criteria for recognition of sedimentary rocks of deltaic origin and also established much needed concepts of deltaic sedimentation. The increase in the number of publications on ancient deltas since 1959 clearly reflects the extensive application of these criteria and concepts to the study of older rocks. This ability to interpret ancient deltaic sediments is one of the greatest achievements in the field of stratigraphy and sedimentology in the past several decades. On the basis of the writer's 30 years of experience in the field of clastic sedimentology, he has selected what he considers to be the most significant contributions to our present understanding of modern deltas and ancient deltaic deposits. End_of_Article - Last_Page 1833------------