Scourse versus John: a rather Scilly spat

Faithful readers of this blog will recall that back in October, Quaternary Newsletter published my short paper on the Isles of Scilly, in which I proposed that the glaciation of the archipelago was rather more extensive than previously postulated.

https://www.researchgate.net/publication/328413421_Evidence_for_extensive_ice_cover_on_the_Isles_of_Scilly 

Anyway, shortly after publication the Editor of the journal informed me that she had received a detailed comment from Prof James Scourse, and suggested that I might wish to respond.  So I did just that, displaying great self-restraint, and the discussion between James and me is now published in Quaternary Newsletter 147 (Feb 2019).

https://www.researchgate.net/publication/331465702_Glaciation_of_the_Isles_of_Scilly_Discussion

I won't enter into a detailed analysis of his point-by-point assault on my competence and my integrity -- apart from saying that I was very disappointed by the tone of his comments.  Readers can form their own view of the proceedings!  We are actually agreed on most things, and James seems to be particularly infuriated by my failure to use the "right" lithostratigraphic labels for certain of the sediments which I describe.   I make no apologies for that.  They are HIS labels, not mine, and I am not convinced that some of them are all that useful for describing a suite of glacigenic deposits which display considerable lateral variations in texture and degrees of modification -- as one would expect in any ice-marginal environment. 

I also stand by everything contained in the original paper.  I am still convinced that the WHOLE of the archipelago has been overwhelmed by glacier ice at some stage in the past.  I am convinced that erratics contained in the raised beaches and other identified coastal sediments have nothing to do with ice-rafting.  I am unmoved by James's conviction that "there is no evidence" for the glaciation of parts of the coasts of Devon and Cornwall.  There is plenty of evidence --it's just that he and I choose to interpret it in different ways.   And I am convinced that the Late Devensian ice which pressed onto the northern and western coasts of the islands was also more extensive than suggested by James Scourse and others.

Ironically, at the end of James's point-by-point attempt to discredit me as an observer and interpreter of Quaternary sediments, he agrees -- somewhat grudgingly -- that I am probably correct!

John did not visit the islands of Annet and Samson but argues that future investigations of these islands “may suggest that a lobe of ice pushed in from the west”. Recent observations from the west coast of Samson (D. Mawer, pers. comm., 2017), supported by photographic evidence, are convincing to me in indicating an exposure of Hell Bay Gravel here. If this is correct it would indeed represent a change in the ice limit on Scilly. This locality, and the sections described by John, require independent assessment and thorough description. It is likely that some details of the Late Devensian ice limit on Scilly will be redrawn as new sections and new observations come to light. 

So -- a lot of insulting bluster about nothing very much, and I look forward to further research which will help us to decide exactly where the Late Devensian ice limit was located.  It looks as if I am not far out with my ice limit proposal for the isle of Samson.  Next, evidence is needed from Annet, which, I suspect, was overridden by ice.  But access isn't that easy, and because it is a nature reserve used by nesting sea-birds, fieldwork visits probably have to be concentrated into the autumn and winter seasons.

See also:

Smedley, R.K., Scourse, J.D., Small, D., Hiemstra, J.F., Duller, G.A.T., Bateman, M.D., Burke, M.J., Chiverrell, R.C., Clark, C., Davies, S.M., Fabel, D., Gheorghiu, D.M., McCarroll, D., Medialdea, A.M., Xu, S. (2017). New age constraints for the limit of the British-Irish Ice Sheet on the Isles of Scilly. Journal of Quaternary Science, 32, 48-62. doi: 10.1002/jqs.2922

http://onlinelibrary.wiley.com/doi/10.1002/jqs.2922/epdf

Map showing the dated sites on the north coasts of Scilly, all within the putative Late Devensian ice limit.  As I have mentioned before, I am amazed that such experienced Quaternary scientists did not collect any control samples or undertake any dating work outside this limit -- which was and is hypothetical.  If they had, they may have found something interesting........ such as a more extensive ice cover.