I have become intrigued by finding some references to a "striated bluestone" at Stonehenge, which figured in some debates between geologists around the time of HH Thomas's early pronouncements about the "impossibility" of glacial transport (around 1920-21).
There are two key publications which pre-date Thomas's famous 1923 publication in The Antiquaries Journal. One was in the same magazine, vol 1, 1921, pp 39 and 40, in the discussion about Hawley's report on the 1920 excavations. The other was in the Memoirs of the Geological Survey, "Summary of Progress for 1921", published in 1922, pp 56-57.
According to Stephen Briggs, in his article "Preseli, Stonehenge and the Welsh Bronze Age", Thomas pointed out that there were many large boulders suitable for use as orthostats on the south coast of England between Selsey Bill and the Isle of Purbeck. They were all of rock types "unrepresented among the stones of Stonehenge." He planned to investigate these boulders again -- but it is unclear whether he ever did so. But in 1921 he was proposing very strongly that the bluestones were selected in Pembrokeshire and transported all the way to Stonehenge by human agency. He did not have it all his own way. William Dale reiterated Judd's view that the stones were glacial erratics. On one of the fragments "exhibited" by Thomas, Dale detected glacial striae. The Rev GH Engleheart, who knew the geology of Wiltshire and Dorset very well, was also unconvinced by Thomas's assertion, arguing that the evidence of stone dressing at Stonehenge did not make sense -- why would people carry undressed stones all the way from Wales, only to modify them and reduce them in weight after arrival rather than before? He also argued that the stones did not look like quarried stones but like an ill-assorted assemblage of erratics -- and he agreed with Dale that one of them was striated.
I have seen no other mentions of this "striated bluestone" -- how big was it? If it was "exhibited" by Thomas, presumably it must have been a smallish stone capable of being carried around to lectures?
Can anybody enlighten us on this mystery?