Biological processes at Rhosyfelin

I'm increasingly convinced that biological processes are -- and have been for a long time -- of great importance in the evolution of the landforms at Rhosyfelin.

If one looks back at the Devensian, and at the history of other crags and rock faces (for example, on the coast) one sees the effects of frost shattering over a period of around 70,000 years -- during which there must have been continuous or discontinuous permafrost and an ongoing process of rock breakage at the surface.  Many fracture patterns must have been exploited, with fractures opened or widened by freeze-thaw processes.  Then, in the intervals when scrub or woodland vegetation was able to take hold, the expansion of root systems must have continued the work, forcing fractures to widen even further, until failures occurred, accompanied by large and small rock fragments crashing down and accumulating on the flank of the crag.  This is what we see in all the photos -- interpreted as quarrying waste by the archaeologists and as natural rockfall or slope accumulations by geomorphologists.  

The process continues to this day -- maybe at a faster rate now than in the past, given the nature of the present climate and the occupation of the upper part of the crag by  gorse, hazel, willow and other bushes and small trees.  Root expansion does part of the work, the the rocking of trees and shrubs in the wind is another very active process.  I'm planning more work on this -- watch this space.........