Diesel interference patterns after spill

We are now back opposite the moorings at Lyon's Boatyard. As we approached we became aware of diesel on the water making its unmistakeable interference patterns. If I remember my school physics correctly, this is caused by light reflecting from the surface of the diesel combining with light reflecting from the water surface, just a molecular distance further. The thickness of the diesel is so small, approaching the wavelengths of light, interference patterns are set up revealing light's component colours in a rainbow effect. I'm sure someone will tell me if I've got this wrong.

As the diesel spreads out from the original spill I believe that surface tension effects quickly cause it to be only a molecule thick, i.e. not very thick at all. So a small spill can cover a large area, making it look worse than it probably is.

The next day there was no evidence of the diesel.

This afternoon Scorpio came past.

Jubilee is tied up on the towpath.