THE EMPIRICAL RELATIONS BETWEEN MD AND σ COEFFICIENT OF SANDS AND THEIR REFLECTION ON THE DEPOSITIONAL ENVIRONMENT

The size analysis of sands in the littoral area of Qinhuangdao shows that the empircal relationships between median diameter, Md, and sorting coefficient,σ, of sands different types and characteristics due to various geneses and hydrodynamic conditions.Therefore,they may be attributed to different depositional environments. A linear σ-Md graph with ascending grade suggests that the sorting of sand particles becomes better as they run way in removal and grow smaller in size, which implies a normal state of depositional differentiation.And down-sloped σ-Md line indicates that when sand particles grow smaller in transportation, their sorting becomes poorer. This means an abnormal depositional differentiation by the disturbance of wash