This set of papers has grown from a special symposium "Placer deposits through time" which was part of the Sixth International Conference on Fluvial Sedimentology held in Cape Town in September 1997. The papers reflect important linkages, which have developed since the first Fluvial conference held in 1978 in Calgary, between pure and applied research into placer formation in sediments. Placer deposits are concentration of relatively dense detrital minerals that accumulated in fluvial, marginal marine, or eolian environments as a result of sediment transport mechanics. Papers in this issue focus on fluvial placers, which are the most important from the economic point of view. They have been mined in many parts of the world for thousands of years and still constitute the most commonly, and volumetrically the largest, exploited placer type.