By Professor T. Rupert Jones, F.RS., F.G.8., Se. 141 
all lying horizontally at the same depth in reddish clay. One of 
them, which I uncovered a short time since, is of enormous dimen- 
sions, being 9ft. 6in. by 9ft., and 25in. in thickness. A ploughman 
informed me that in cultivating the field the surfaces of others are 
sometimes touched near the same spot; and small stones of similar 
character abound in the vicinity, especially where pits have been 
dug for chalk.” The Rev. J. Adams, Transact. Newbury District 
Field; Club, 1871, p. 107. 
Mr. Adams proceeds to describe some large concretionary stones 
actually in place in the sand of the Woolwich-and-Reading Beds, 
_at Langley Park, near Beedon, about four miles E. by N. from 
~ Hangmanstone Lane, as Sarsens also, but, I believe, erroneously. 
The chief block is also described in the Catal. Rock-Specimens, 
Mus. Pract. Geol., 1862, p. 169, and is referred to by Mr. Whitaker 
in the Memoir Geol. Survey for Sheet 13, p. 41, and Q. J. G.S., 
vol. xviii., p. 272, as a Sarsen; but, as I have explained (Geol. 
Mag., New Series, vol. ii., p. 588, and Trans. Newbury District 
Field Club, vol. ii., 1878, p. 249), this has a calcareous (not a 
siliceous) cement. It is, therefore, not a “Sarsen.” If it had been 
exposed to the destructive action of moving water, like the real 
Sarsens have been, it would have been worn away, with the 
dissolution of its cement, just as, doubtless, many of its congeners 
have suffered. 
In the progress of the Geological Survey of England, Mr. W. 
Whitaker, F.G.S., noticed the occurrence of Sarsens in places on the 
London Clay, thus being above the present position of the Woolwich- 
and-Reading-Beds,—that the Lower Eocene strata thin off westward 
of Hungerford, and terminate altogether near Marlborough,—and 
that the Bagshot Sands must have overlapped them there, and rested 
directly on the Chalk; so that when the sands were swept away 
by denudation their included concretionary blocks remained on 
what are now the Marlborough Downs and neighbourhood.! As 
above-mentioned (page 134), the Sarsens of the Frimley area are 
directly connected with the Bagshot Sands. Elsewhere, as Professor 
1 In the Quart. Journ, Geol. Soc., vol. xviii., pp. 258—274, his views are given 
at length. 
