Mr. Webster on the Strata lying over the Chalky 245 



stratum of London clay, but always upon it, and frequently accom- 

 panied by marl and freshwater shells. 



Other bones of ruminating animals, as those of the horse, ox, 

 and stag, not different from the living species, are frequently dug 

 up at small depths, and are covered by peat, gravel, loam, &c. 



In the freshwater formations of the basin of Paris the bones of 

 terrestrial animals are found, which do not belong even to known 

 genera, and many of those found near the surface in their alluvium, 

 belonged also to animals of great size, and which are now found 

 only in countries very remote. 



We see therefore that a similar succession of animals has lived in 

 this portion of the earth, during the various stages of its habitable 

 state. 



V. Concludhig Obscrvat'iotis. 



One of the most interesting consequences deducible from the 

 above examination of the last formed strata of this country, is, 

 perhaps, the view which it seems to afford us, of establishing, in 

 some degree, a series of epochs between the deposition of the chalk: 

 strata and the formation of the present surface of the land ; not 

 indeed to be distinguished by computable time, since no date can be 

 affixed to any of the changes to which I have alluded, but an order 

 of succession of the great events at least appears more than hypo- 

 thetical, which it may be useful still further to consider. 



The origin of the calcareous matter of which the chalk formation 

 Is composed remains one of those hidden mysteries on which all the 

 speculations of geologists have not thrown any certain light. 



In the several strata of chalk however, although their sources were 

 probably not very different, we may perceive several circumstances 

 which indicate the action of modifying causes in each deposition, 



