The Rev. W. Buckland on the Plastic Clay Formation. 283 



Newbury on the road to Whitchurch. On the west of this line, 

 drawn through Newbury north and south, the breadth of the beds 

 on the chalk is gradually contracted till they entirely cease near 

 Hungerford (See Mr. Webster's map, Geol. Trans, vol. 2, pi. 10). 

 On the east side of the said line they occupy the vale of the Kennet 

 till it falls into that of the Thames, near Reading ; whence they 

 extend eastward, widening as they advance through Surry and 

 Middlesex, into Kent, Essex, Suffolk, and Norfolk. 



In many parts of this great valley or trough of chalk we recog- 

 nize our Reading beds in their proper place, as the inferior strata 

 of the plastic clay formation ; and though with^the exception of 

 the lowest bed they do not agree in minute detail with those of 

 the Reading section, as to thickness, or exact order of superposi- 

 tion, nor is the presence of shells or pebbles constant in the beds 

 of clay or sand, yet an attentive examination of the general points 

 of resemblance in the substance of the clays, sands, and pebbles, 

 forming these irregular alternations above the chalk, added to the 

 identity of their organic remains when any occur, leaves no doubt 

 as to their being members of one great series, of nearly contempo- 

 raneous depositions, intermediate between the chalk and London 

 clay, and which it may be convenient to associate in a natural 

 family, as members of that formation of which it is one leading 

 feature to contain those peculiar varieties of clay which the French 

 naturalists have characterized by the appellation of plastic clay. 

 As there can be little doubt of the origin of the French beds being 

 contemporaneous with those in England we are now considering, 

 it will assist us in connecting our strata with those of the Conti- 

 nent, to designate them by the appellation appropriated to them in 

 France. 



Near London these beds occur with well defined characters ; at 



