uo 



History of the Bar sens. 



VI. — Professor Prestwicii and others on Sarsens. 

 The first exact study of the distribution and origin of the Sarsens 

 was carried out by Professor Prestwich, E.R.S., as published in the 

 Quart. Joum. Geol. Soc, vol. x., 1854 (in a paper read May 18th, 

 1853). At pages 123—130 careful notes on the chief places where 

 blocks of Druid or Greywether sandstone occur, 1 and exact arguments 

 in favour of the view that they werederived from the Wool wich-and- 

 Reading Beds, rather than from the Bagshot Beds, to which they 

 had been previously referred, are clearly and succinctly given. The 

 possibility that some in Kent might have come from the Thanet 

 Sands and from one part of the Basement-bed of the London 

 Clay, is pointed out ; and the " blocks irregularly dispersed, some- 

 times in the lower, but more especially in the upper division of the 

 Bagshot Sand between Esher and Strathfieldsaye " (p. 123) are not 

 lest sight of. The conclusion arrived at was that " the whole group 

 of the Druid Sandstones of Wilts, Hants, Bucks, and Kent, and of 

 the Puddingstones of Herts" were derived from the Woolwich- 

 and-Reading Beds. In the sands of these strata Mr. Prestwich 

 had observed concretionary blocks in place at Nettlebed Hill, north 

 of Reading ; also near Chesham, Elstree, Pinner, and elsewhere. 

 He notes, moreover, similar sands, with concreted blocks, on the 

 French coast near Dieppe, being a prolongation of the Woolwich 

 Beds of Sussex. The abundance of Sarsens near Lambourne, 

 Berks, Mr. Prestwich refers to the former existence there of such 

 sands (W.-and-R. series) as occur at Wickham, about six miles to 

 the S.E. ; and in connection with a patch of strata of the same 

 formation, three miles N.E. of Wickham, a tabular mass of Sarsen 

 Stone was discovered by the Rev. John Adams at Wei ford- Wood- 

 lands, near Hangmanstone Lane. " It was 10ft. or 12ft. in width ; 

 and lay horizontally within a few inches of the Chalk. As its 

 surface was barely plough-deep, it was thought expedient to get rid 

 of it ; and after attempts were made in vain to break it up, a pit 

 was dug on one side of it, into which it was tilted. In making the 

 excavation the edges of three other tabular blocks were laid bare, 



1 Mainly in the Chalk districts of Wilts, Berks, Oxfordshire, Bucks, Herts, and 

 Kent. 



