By Professor T. Rupert Jones, F.R.S., RG.S., Sfc. 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. Bock-Specimens, 

 Mus. Praet. 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. 

 Ma-., 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 Hun-erford, 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. 1 As 

 above-mentioned (page 134), the Sarsens of the Frimley area are 

 dire etly C onnected_wlthth^ 



at length. 



