In other places, patches of thick scum covered the surface.

The drive was appalling, Abu's little car slithering in the thick scum of mud on the desert sand.

Just north of the mountain in a box canyon is a green pool covered with a thick scum.

There appeared to be a fog rising with the coming of evening, a thick scum of stuff closing between the flitter and the ground.

The lagoon was covered by a thick scum of wind spume, creamy as the head of a good beer.

The fireplace was full of water, with something that looked like thick foamy scum floating on it.

Its walls were covered with a thick black scum.

There was a thick soapy scum thrown up along the edge, and it had coated the stems of the reeds.

He left a thick scum of blood on the surface of the water.

With a flat stick, he skimmed off the thick scum of charcoal and coagulated impurities.