Scum

According to the Oxford English Dictionary scum is:

A film or layer of floating matter formed upon the surface of a liquid in a state of fermentation, ebullition, etc.; hence, a film formed upon stagnant, foul water, etc. More generally, any undesirable surface layer or deposit, usually but not necessarily on a liquid.

or when applied to persons:

The offscourings of humanity; the lowest class of the population of a place or country.


This turbulent scum was floating on the River Ythan this morning. The mathematics behind those complex patterns are quite beyond my O level maths!