The results of previous beach tracer work is questioned on the grounds that those tracers found on the beach surface may not have been representative of both the original composition of the tracer population and the performance of the background beach material. The results of tests carried out during a tracer experiment on a pebble beach near Gileston, Wales, United Kingdom, to find out how "returned populations" of tracers matched up with the original population in terms of their distribution of particle parameters revealed significant differences. A second series of tests showed how few tracers had parameters which lay close in value to those of the background beach particles with which they were in close contact. A model for the selective deposition of sedimentary particles in rivers, modified to fit a beach environment, is proposed to account for these observations. It could help explain why tracers located on the beach surface are more likely to be unrepresentative of the background beach material in both character and performance. The particle parameters used in these tests were long(A), intermediate(B), and short(C) axis; surface roundness; Maximum Projection Sphericity (M.P.S.); and Oblate-Prolate Index (O.P.I.).