Architect-426 writes:
The fact that there is very little topsoil on these monoliths is evidence of a recent event.
I believe you are a bit ignorant of how topsoil is formed.
Top soil is typically only 2 to 8 inches. It is formed by the mixture of biodegrading organic matter with mineral sediments. The reason why topsoil layers are thin and relegated to the "top" is because that is where the majority of organisms die supplying organic matter. Also, the decay of these organisms requires consistent air supply as well as organisms to facilitate the decomposition (bacteria and fungus).
Also, topsoil layers are in constant flux due to erosion. Every time it rains in Scotland, which is about 180 inches per year in the western highlands, some of the topsoil is carried down from the mountains by gravity into the vallies. This flux keeps the topsoil layer in the highlands thin.
So, the "thinness" of the topsoil layer in Scotland is not due to recent volcanic activity but rather erosion.
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