This was seen in a hill range called the Fannichs, in a stream that flows into Loch Glascarnoch, about 20 miles from Ullapool. Does anyone know how or why it was formed?
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First, I don't think this has anything to do with wildlife - at least not directly. I think you need a water chemist, and a physicist.
I don't recall ever seeing something quite like this, but similar things are not unusual in the Highlands. What follows is speculation.
The white foam is located in a small bay, where I suspect there is a slow eddy, isolating the foam in a slowly rotating mass. I usually see circular *raised* areas in that situation, like lumps of meringue. I suspect that the flat 'discs' are these lumps once collapsed.
Two questions remain - what forms the foam? And how do the circular masses form? On the first, I have always assumed that it comprises a cocktail of complex organic molecules (proteins, carbohydrates, etc.) from the surrounding peat. On the second, I have not a clue, but suspect that the answer lies in arcane physical chemistry interacting with the flow of the burn.
I can't point you to an appropriate expert, I'm afraid. I hope this find enhanced your trip to that superb range of hills.
recording wildlife with The Recorder's Year on www.hbrg.org.uk/TRY.html.
Very unscientific response to the formation of the discs: it looks quite cold there - I'd suspect that the discs are nearly frozen and as small particles get stuck in whirlpools, more and more particles join, and because it is cold, the stuff freezes and forms a disc.
...is a North American term I recalled for this phenomenon. Checked it on Google and found this Wiki page:
Lat/Lng: 57.6, -5.0
OS grid ref: NH2168