NOTES AND QUERIES. 



Ill 



shells ; the characteristic one of which is Pholadomya cuneala. This sand- 

 stone does not effervesce with acids, except in portions which show evident 

 traces of shells. Beneath this at f we have grey or blue marl, the upper 

 portion immediately under the sandstone being mostly composed of a green 

 sand abounding in shells much like Cyprina Morrisii. This rock passes into a 

 tenaceous grey plastic clay, very hard, and possessing a complete conchoidal 

 fracture. Tins grey marl is very distinct in colour and appearance from the 

 green sandstone above ; it abounds in lignite and iron pyrites. The depth of 

 the Beakesbourne cutting is about thirty-five feet. The average depth of stratum 

 f is about eighteen feet, of e about ten feet. 



The fossils found in the green sandstone, e, consist of Pholadomya cuneata, 

 Pholadomya Koninckii, Cacullea decussata, or C. crussatina ; small Corbida (? J, 

 Cytherea, Cyprim, Turrit ella, Natica, Gly timer is and Panopeea in casts ; fossil 

 fruits ; several casts of Pholadomya, differing from most already described ; 

 some Echinanthus, or Echinoderm. 



In the grey marl, F, were found Pholadomya margaritacea (?), Rostellaria, 

 Cyprina Morrisii, Natica, Pinna, Tellina ; also a supposed Venericardia. 

 Several curiously cylindrical bodies resembling Calamites, lobsters' claws, &c * 



Prom the organic remains found in these cuttings we should have no difficulty 

 in referring them to the Thanet sands of Prestwich, but they seem to differ in 

 lithologicai character, and approach very closely to those sections described 

 by Sir Charles Lyell, as occurring at Tournay, under the term of Glauconite, 

 and grey marl, and classed in Belgium as the Lower Landinian. It has been 

 surmised that these formations in Belgium were represented in Britain by the 

 Thanet sands ; and these sections I have described would seem to warrant the 

 conclusion. I have attentively read Mr. Prestwich' s paper on the Thanet 

 sands ; but do not find that he has described any portion which exactly corres- 

 ponds with these sections. He speaks of the Thanet sands as to their lithologic 

 character, and describes them as " consisting essentially of a base of a light- 

 coloured quartose sand, mixed in its lower beds more especially with more or 

 less argillaceous matter, but never passing into distinct clay" The argillaceous 

 matter is usually light-coloured, and does not therefore colour the sands, merely 

 giving a certain amount of cohesion, so that when dug the beds are sometimes 

 semi-indurated. In some places moreover, the clay with which the sands are 

 mixed is dark coloured, as m the lower beds at Pegwell and Heme Bay." 



The sands described as dark coloured by Mr. Prestwich, are for the most 

 part not accessible, being below low-water, or obscured by recent deposits ; 

 and it must be remembered that the sands at Beculver are represented as 

 being seventy feet down to the chalk, though only twenty-five feet of them are 

 exposed. It would thus be seen that Mr. Prestwich's description would only 

 refer to the upper part, and this the least considerable. However this may be, 

 I believe that there is much yet to be learnt of this important geological forma- 

 tion, and these cuttings I have been describing may reward the search of the 

 diligent geologist. Before concluding, I may add that I have had the oppor- 

 tunity of observing the lower beds of the Thanet sands, having sunk a well at 

 Stourmouth, passing through the Thanet sands down to the chalk, which I 

 reached at a depth of one hundred and forty feet from the surface, and a depth 

 of one hundred feet from the lowest bed of sand ; so that this dark coloured 

 blue clay, which I term the basement bed of the Thanet sand is of considerable 



* It is not to be supposed that this is anything like a complete list of the fossils found in 

 these cuttings, but most of those I have had an opportunity of examining ; and the difficulty 

 attending the correct determination of species from casts and shells in which the hinge is 

 not exposed, renders the correct naming of these specimens, by so inexperienced geologist as 

 I am, a matter of great difficulty. I, therefore, with great diffidence give the names as an 

 approximation of the truth. — G. D. 



