The bottom sediments of the Adriatic sea near the Italian coast were sampled and analyzed. These sediments were transported as uniform suspensions. A close relation was found between certain grain-size parameters, particularly the one percentile, and sea depth, indicating that turbulence induced by waves was a major factor in sand distribution. Another important factor is percentage of sand in the sediment source for the area. If these source sediments contain little sand and consist almost entirely of silt and clay, the sand remains close to shore. If, however, sand is the predominant constituent of the source sediments, as commonly occurred in ancient seas, sand probably can be spread by waves across extensive areas as deep as wave base. The grain size of the sand also is an important factor in its distribution, some sand suspensions being displaced by gravity and some not. Therefore, grain size may determine the transport mechanism and, thus, the sediment distribution.