52 Mr. Warburton on the Basrshot Sand 



b' 



Among the diluvian debris dispersed over the surface of the heath, quartz 

 crystals are not uncommon. Near Farnborough are found upon the surface 

 fragments of an arenaceous limestone^ containing many fossil shells, and 

 among the rest, dentalia. It is to Mr. Stokes that I was first indebted for the 

 information respecting these fragments. 



I have lately succeeded in ascertaining the bed from which these fragments 

 are derived. They come from the stony concretions which are found in the 

 beds of sand belonging to the plastic clay, that extend through the low coun- 

 try between Windsor and Reading at the foot of Windsor Forest. They 

 resemble the stony concretions that are found in the same bed at Sundridge 

 Park near Bromley, and agree, perhaps, with those of Bognor rocks. 



The existence of these specimens was first announced by Lord Grenville to 

 my friend Mr. Buckland, in company with whom I examined them in situ. 



The place from which the specimens of these stony concretions in the plastic 

 clay which I now send were taken*, is the water-course lately made for the 

 purpose of draining the newly-inclosed lands of Windsor Forest, on the road 

 that leads from Hollyport to Binfield. The sand with its concretions there 

 rests upon variegated plastic clay. The shells are the Reading oyster, a 

 Pecten, a large and small Cardium, a Pectunculus, Nucula margaritacea, two 

 species of Citheraea, a shell resembling Solen radiatus, a Tellina, a Dentale, 

 Strombus pes-pelicani, Calyptraea trochiformis in great perfection, and se- 

 veral imperfect turbinated shells. There is also a shark's tooth, pyritous 

 wood, and what appears to be the seed-vessel of a marine plant. It is remark- 

 able that the Cerithia, which are found in the same beds in Sussex and near 

 to London, are wholly wanting in the beds at Reading and at the spot in 

 question. 



I propose at some future period to examine the sands of Dorsetshire and 

 Hampshire, which, I have very little doubt, will be found to belong to the same 

 formation as the sand of Bag-shot Heath. 



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* The specimens here referred to arc in the Museum of the Geological Society* 



