66 On the Order of the Upper Strata 



and unknown agents. It is composed chiefly of water-worn 

 fragments of flints, mixed with sand and clay in various pro- 

 portions. 



Upper Freshnaler Furmalion. — This (in the Isle of Wight) 

 consists of a calcareous rock, in which numerous fossil fresh- 

 water shells are imbedded. It agrees in character and situation 

 with tlie corresponding formation in the basin of Paris, and 

 other parts of the continent of Europe. Traces of a freshwater 

 formation are to be observed also in the London basin, between 

 the alluvium and London clay, consisting of marl with fresh- 

 water shells, and containing also numerous bones of land ani- 

 mals, as the elephant, hippopotamus, buffalo, elk, ox, &c. 

 These have been found chiefly at Sheppey, Brentford, Essex, 

 Suffolk, and Norfolk. In other places, as at Sheppey, Ems- 

 worth in Sussex, &:e. vast quantities of the fruits of tropical 

 countries have been found in a corresponding situation. 



Upper Murine Formation. — This bed consists of blueish or 

 greenish marl and clay containing a great number of fossil marine 

 shells, which in general are different from those found in the 

 London dav. It is known in this country with certainty only 

 in the Isle of Wight. 



Lower Freshwater Formation. — This formation is ascertained 

 in the Isle of Wight. It is placed under the last, and consists 

 of clav, marl, and sand, with vegeiable matter resembling an 

 imperfect coal or peat, and contains numerous fragments of fresh- 

 water shells. At the bottom is found a mixture of marine with 

 fresh -water shells. As the alternation of marine with fresh-water 

 strata has not been observed in any other part of this country 

 except the Isle of Wight, the traces of a fresh-water formation 

 in the London basin cannot perhaps be referred to this. 



Sand without Shells. — In the Isle of Wight this sand is ex- 

 tremely pure ; it is dug at Alum Bay, and is used for making the 

 be-.t glass. The Ba^shot sand perhaps belongs to this, and pos- 

 siidv the Grayweathers ; but the positions of these have not yet 

 been accurately determined. 



London Clay. — This is the blue clav of London, Highgate, 

 Brentford, Sheppey, Portsmoutli, Stubhington, Hordwell, South- 

 end, Harwich, &(,. It is distinguished by its septaria, and its 

 beautiful and numerous organic remains. In Alum Bay it is the 

 most northerly of the vertical strata. Bognor Rocks are subor- 

 dinate to this bed. It agrees in it:^ fossils and geognostic situa- 

 tion with the lower beds of the calcaire grossiere of the Paris 

 basin. 



Plastic Clay and Sand. — The clay in this formation is often 

 extremely pure, and lit for the potter. It is much employed in 

 the potteries in Staffordshire, It is seen in Alum Bay, the 



trough 



