“…Concentrations at the coast or inner contine ntal shelf may ( result from selective sorting Komar & Wang, 1984;Isla, 1991;Frihy & Komar, ) ( 1993;Boon & Berquist, 1991, relict accumulations Nelson, 1971; Paulson & ) Owen, 1996 , or either to spatial or temporal variations of provenance or erosive ( processes Pilkey, 1963;Swift et al, 1971;Scheidegger et al, 1971;Woolse y et al, ) 1975;Jones & Davies, 1979;Hamill & Ballance, 1985;Paulsen & Owen, 1996 . ( ) In a much broader approach, Potte r 1994 stressed that the mineral composition of South American be ach sands is controlled by the tectonic history and climate.…”