John Faithfull ππͺπΊπ΄σ §σ ’σ ³σ £σ ΄σ Ώπ§‘βπ»βπΏ#DogWalkingGeology Some mysterious round colonies of marine algae and some limpets all enjoying their solid substrate of Moine garnet-amphibolite at Ardalanish this morning. π #Mull #Geology #Gastropods
Peter L Bowden@FaithfullJohn Ah ha, I think that solves a mystery. Whilst out and about looking at the wonderful Lewisian I have frequently encountered black circles and disks, (photo attached).
I presume when the algae dies it blackens. This might also explain the so called "oil staining" (a term much used by the giants of OH Lewisian exploration in the 60s and 70s), which can obscure large areas of coastal exposure.
