Twenty-five samples from six subenvironments in the barrier-lagoon systems in northeastern Shandong province, China, are examined. A statistical method is used to study the roundness variation of grains of different sizes. Roundness of very fine pebble and very coarse sand varies significantly in different subenvironments. It is possible to discriminate among aqueous depositional environments using the roundness of grains of these sizes. Roundness of grains finer than 0.84 φ is not distinguishable in different subenvironments.

Roundness decreases with decreasing grain size. The differences among grains of different sizes are most remarkable on barrier beaches, but few differences can be observed in the underlying flood-fluvial sediments of the barrier-lagoon systems. These indicate that grains of different sizes have different potential for being rounded. Grains finer than 0.84 φ are very difficult to round, even on high-energy beaches. Short distance of transportation and brittleness of grains both inhibit the rounding of grains.