A HISTORY OF BERKSHIRE 



seemed to bear the marks of roots, he adds, 'It is by no means improbable 

 that the decomposition of vegetable matter and consequent formation of 

 humus, and the various organic acids which arise from its gradual 

 alteration into carbonic acid, may have had something to do with the 

 concretionary action.' 1 A somewhat similar opinion has been expressed 

 by the Rev. Dr. Irving. 2 Greywethers or sarsens are often to be seen 

 at the corners of roads or used as stepping stones, and, as stated in the 

 passage in Lyson's referred to above, they have been used as building 

 stone. Mr. H. B. Woodward remarks that much of Windsor Castle is 

 built of greywether sandstone. 8 



In the sandy and clayey districts the older buildings often consist of 

 a considerable variety of material. The tower of the church of Waltham 

 St. Lawrence, for instance, is built mainly of chalk and of flints, but 

 there are also several fragments of sarsen, a number of blocks of irony 

 conglomerate and a few bricks. 



In addition to the works referred to above, several papers relating 

 to Berkshire will be found in the recent volumes of the Quarterly 'Journal 

 of the Geological Society f , the Proceedings of the Geologists' Association, and 

 the Geological Magazine. 



1 Pnc. Geol. Assoc. (1881-2), vii. 138. * Ibid. (1883-4), viii - 'S3- 



3 Geology of England and Wales, ed. 2 (1887), p. 449. For further details of sarsens in Berkshire 

 see T. R. Jones, Geol. Mag. (1901), viii. 54, 115. A bibliographic list of works treating of sarsens 

 will be found at p. 124, and a paper by the same author in the Berks, etc. Arch. Journ. for July, 

 1901, vii. 54. 



