140 History of the Sarsens. 
VI.—Proressor Prestwich AND OTHERS ON SARSENS. 
The first exact study of the distribution and origin of the Sarsens 
was carried out by Professor Prestwich, F.R.S., as published in the 
Quart. Journ. Geol. Soe., 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,’ and exact arguments 
in favour of the view that they were derived from the Woolwich-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 
lost 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 Welford-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. 
