Sea Foam Tide-marks on Rusty Iron

Dried sea foam on rusty iron

I noted an interesting phenomenon at Weymouth in Dorset recently. The rusty iron panels of the pier structure exhibited tide-marks or tide-lines of dried sea foam from a previous high water. I have never seen that before. The contrasting colours, patterns, and textures of the creamy lines against the multi-coloured oxidising metal made interesting compositions.

Wikipedia says about sea foam:

Sea foam, ocean foam, beach foam, or spume is a type of foam created by the agitation of seawater, particularly when it contains higher concentrations of dissolved organic matter (including proteins, lignins, and lipids)[1] derived from sources such as the offshore breakdown of algal blooms. These compounds can act as surfactants or foaming agents. As the seawater is churned by breaking waves in the surf zone adjacent to the shore, the presence of these surfactants under these turbulent conditions traps air, forming persistent bubbles that stick to each other through surface tension. Due to its low density and persistence, foam can be blown by strong on-shore winds from the beachface inland.

15 thoughts on “Sea Foam Tide-marks on Rusty Iron

  1. Thank you, Evelyn. The rust colours are unusual but I once saw a piece of iron mineral in the Geological Museum in London which had the same range of wonderful colours with deep blues and purples.
    Here is a picture of the rock specimen:
    Museum specimen of iron with iridescent colouring.

  2. Love this collection of photographs! I’ve never seen a breakwater like this. Now I will have my hopes up to find one some day—though you’ve captured it all in your photographs.

  3. Thank you, Linda. At the landward end where I took these photographs, these interlocking iron panels crossing the sandy beach are part of a structure that supports a road to the harbour and a seaside pavilion (a kind of theatre). As it extends seawards, it becomes more of a traditional British pier which was designed to make it easier for boats to dock when the tide is low as well as a pleasant place for people to promenade or fish.

  4. Thank you, Judith. It is a place that I like to visit and it often changes its appearance. I guess the light and weather both affect the corroding surface.

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