me. a. strahan on the lincolnshire carstone. 493 



Discussion. 



The President said that he had listened to this paper with great 

 pleasure. The one point of difference between himself and the 

 Author may be easily explained. At the time when he described 

 the structure of the district, the Lower Greensand of the south was 

 regarded as one, but since then the break between the Polkestone 

 Beds and those below has been clearly shown by Barrels, Meyer, 

 and others. He was quite prepared to accept the Author's general 

 conclusions. 



Professor Hughes considered the paper a valuable contribution 

 to the geology of East Anglia, and hoped that the Author would 

 press the legitimate conclusion that the Carstone series was the 

 basement-bed of the Cretaceous, and would abolish the bracket 

 which in his diagram linked it to the bed below, whether called 

 Tealby Series or Neocomian. He thought the Author might extend 

 the story of the manner in which the Lower Greensand, or Carstone, 

 creeps transgressively over the older formations, if the few inches of 

 sand which rested on the Wenlock in the Ware boring should, as 

 he believed, turn out to be the geological equivalent of the Car- 

 stone. 



Mr. Whitaker stated that he did not know the district referred 

 to by the Author, but that he knew the north-western part of ISTor- 

 folk. He agreed as to the conformity at Hunstanton between the 

 Red Chalk and the Carstone. The occurrence of stone was more 

 or less a matter of accident, and the presence of about 10 feet of 

 clay between the sandy beds and the Eed Chalk in the well at 

 Holkham perhaps indicated the presence there of Gault. The con- 

 formity between the Carstone and the Eed Chalk was a singular 

 thing ; in Bedfordshire the Gault sometimes scoops into the Lower 

 Greensand. Where there is a considerable absence of beds, as 

 where Eed Chalk rests on Carstone, you may have conformity just 

 where one would least expect it. He was doubtful as to the oc- 

 currence of the Carstone in the boring at Ware. 



The President called attention to the interesting section at Skeg- 

 ness where the Neocomian clays thickened out so remarkably, and 

 he observed that they continued their increased development to the 

 eastward in Germany, where they are known as the " Hilsthon." 

 Their thickness at Skegness was the more remarkable, considering 

 the shortness of the distance from their outcrop in the Downs, 

 where they were of insignificant thickness. 



The Author said that, as regarded the bed in the boring at Ware, 

 if it were Carstone it proved his point. He gave particulars as to the 

 section at Skegness, and stated that it was over 250 feet to the base 

 of the Spilsby Sandstone, which had dwindled down to a few feet in 

 thickness and had been in part replaced by clay. The Spilsby Sand- 

 stone would seem to have been a shore-deposit. 



