110 



PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 23, 



The following communications were read : — 



1. On the OccTTEREiTCE o/ CoN^soLiDATED Blocks in the Drift of 

 Suffolk. By Geoege Maw, Esq., F.L.S., F.G.S., &c. 



As a contribution to the evidence on the geological position of the 

 blocks of saccharoid sandstone scattered on the surface of many- 

 parts of the chalk- districts, I beg to lay before the Society a brief 

 account of the occurrence of similar blocks of large size in the Drift 

 of Suffolk, both in situ and on the surface. In the chapter on " Druid 

 Sandstones" or ^'Sarsen Stones," in Mr. Prestwich's paper on the 

 Woolwich and Eeading Series (Quart. Journ. Geol. Soc. vol. x. p. 123), 

 the original source of these remarkable blocks is assig-ned to the sand- 

 beds of the Woolwich and Reading Series, but less from the direct 

 evidence of their actual occurrence in situ than from the mineralogical 

 resemblance of the consolidated blocks to the Woolwich and Beading 

 Sands, and from their geographical distribution pointing to a deriva- 

 tion from the Lower Tertiaries. A case is also mentioned of the 

 occurrence of such blocks in Drift, in which that author considers 

 that they were derived from the Woolwich and Reading Sands. 



Blocks of saccharoid sandstone also occasionally occur in the Bag- 

 shot Sands, from which they appear to have been consolidated. The 

 blocks, of similar mineral character and structure, about to be de- 

 scribed from the Quaternary Drift of Suffolk, are so placed as to 

 render it certain that they were composed from the sands and gravels 

 of the drift where they now lie ; it would appear, therefore, that 

 such masses are not limited to any particular deposit, but have been 

 consolidated from most of the sandy formations resting on the Chalk. 



The accompanying diagram represents the section of a well sunk 

 by Lady Middleton, at Crowfield-Street, near Coddenham, together 



Section from Chopping'' s Hill Farm to Crowfield-Street, near 

 Coddenham, Suffolk. 



(Horizontal distance condensed.) 



Well at Crowfleld 

 Street, 111 feet deep. 



a. Boulder-clay, with fragments of chalk, b. Sand and gravel, 

 blocks, c. Chalk. 



X Consolidated 



with the outcrop of the strata between Crowiield and Coddenham. 



