Abstract
Sometimes white streaks or patches are seen on the sea surface. They look like white and in some cases glassy because of their damping effect of wavelets and are called “Slicks”. Appearance, transformation, movement etc. of, slicks were observed in Beppu Bay. They have some relations with the wind-velocity and wind-direction. It seems that slicks tend to be parallel with wind-direction and to diminish with the increase of wind-speed. Slicks are concerned with the distribution of organic substances in the sea water which are found coming originally from rivers and drains by the aid of Cons. O2-Cl diagram. These organic substances damp out the ripple owing to their lowering effect of surface tension.
