;}4 Notices of Memoirs — Dr. Irving on a Sarsen Sfoiie. 



Bishop's Stortford Town Cemetery, about 7 feet from the surface in 

 the principal Boulder-day of the district, the equivalent of the Chalky 

 Boulder-clay of the Eastern Counties. 



The block is fairly angular, approximately a cube. On one side the 

 fracture of the bed is fairly fresh ; the opposite side is slightly 

 hollowed, as if by the long-continued current action of a shingly 

 stream. For the greater part of its thickness it is a true sarsen ; 

 towards the base a few flint pebbles are scattered through it ; the 

 upper surface passes into a true ' puddingstone ' (an agglutinated 

 mass of flint pebbles), the matrix of which is lithologically the same 

 as, and continuous with, the material of the sarsen. About the middle 

 of the upper side the agglutinated mass of pebbles Alls a small 

 gully in the quondam sand of the sarsen. A subordinate alternation 

 of the true sarsen structure with the pebble-bed structure is seen 

 in the largest examples of puddingstone perhaps in the county.^ 

 A striking lithological feature of this specimen is the distribution in 

 it of numerous small angular bleached fragments of flint. Its 

 dimensions are 30 X 20 X 18 inches, and its weight not less than 

 half a ton. JSTo trace of glacial striations has been detected on it. 



The author refers to his former work on the genesis and distribution 

 of sarsens.* While recognizing their common occurrence in the 

 Lower Eocenes, and even in the sands of the Neocoraiau, he regards 

 those of the interior of the London Basin as the wreckage of a younger 

 formation (late Eocene or Oligocene), possibly the stratigraphical 

 freshwater equivalents of the Stettiner Sandstein of North Germany^ 

 and the Gres de Fontainehleau^ of the Paris Basin. Agglutinated 

 portions of the Bagshot Pebble Beds in situ, with similar siliceous 

 cementation, are known to occur ;^ there is good evidence of the 

 quondam extension of the younger beds of the Bagshot Series 

 (including the pebble beds) over Herts and Essex ; and the author 

 points to this recently unearthed rock-mass as tending to clinch the 

 view advocated by him for years past — that the sarsens and the 

 Herts 'puddingstone' are remnants of one and the same younger 

 Eocene (or Oligocene) formation.^ He considers the latest treatment 

 of the subject by the late Professor T. llupert Jones, E.R.S., and the 

 more recent treatment of it by H. B. "Woodward, E.U.S.," inadequate. 



1 Seen in the grounds of G. E. Pritchett, Esq., F.S.A., Oak Hall, Bishop's 

 Stortford. 



- P.G.A., viii, No. 3, 1883, where critical reference is made to the views of 

 the late Professor John Phillips, F.E.S., of Oxford. 



=* H. Credner, Geologic (Leipzig), 10th ed., pp. 692 ff. 



** S. Meunier, Les causes actuelles en Geologic, p. 289; Credner, op. cit., 

 p. 683. 



^ A. Irving, P.G.A., xv, pp. 196, 236, February, 1898. 



•^ A. Irving, " High Level Plateau Gravels, etc. " : Geol. Mag., No. 484, 

 October, 1904. 



■^ The Geology of the London District (Mem. Geol. Surv., 1909). 



