"The book is worth looking at just for the photographs, many of which are of impressive flashed bunkers, both natural and man-made. Hutchinson's influence on the formative years of golf architecture, both in the UK and US, has been under-appreciated."
That is very true and that book is a very important and central one for us to consider. But the point here is the high sand flashed (original sand dish shapes of sand up to the top line) of Merion were done on a INLAND clay/loam, former farmland site that had no natural sand on it (very ironically apparently the Merion West site had a significant enough sand deposit area). So one could certainly not say that Merion East had any natural upswept sand formations on it as so much of the linksland did and NGLA or Pine Valley or even Sunningdale and Huntercombe had once the natural rough vegetation was removed from it.
So, the question becomes, which is still on the table-----what INLAND clay loam (dirt, basically farmland) site and course and project like Merion East's created sand upswept faces to the top FIRST?
There is no point in comparing Merion East to sand or sandy/loam sites like NGLA, Pine Valley or even apparently Sunningdale or Huntercombe or other heathland sites. We need to find the first examples of that style of bunkers on very different earthen circumstances such as Merion East.
I know that the bunkers of the courses that came before Merion East with essentially its type of earthen circumstance and soil structure such as Myopia, GCGC, Oakmont and probably Baltusrol etc definitely did not use upswept sand faces to the top like Merion originally did. All the courses that came BEFORE Merion East with its kind of INLAND soil makeup apparently used basically flat sand floors in their bunkers.
I'm not saying Merion East was the first that way but it might be. That is all I'm trying to find out as well as if Wilson came up with it first on that kind of site (or else where and how he got the idea on a site like Merion East's). To prove it wrong just find a golf course on and apples to apples earth and soil structure like Merion that had that very same type of bunker that Merion had and that Wilson articulated in that interesting unpublished paragraph above that was written or built before Wilson or Merion East.