332 On the Structure of the Delta of the Ganges. 



a distance. In like manner the flints which are found in 

 the lower beds of the great gypsum formation of the Paris 

 basin pass gradually and imperceptibly into the gypsum itself ; 

 a proof, (says Professor Jameson in allusion to this fact) of 

 the contemporaneous origin of the two substances.* Simi- 

 larly the peculiarly perfect and beautiful state of preserva- 

 tion in which the fossils of the London clay are found, would 

 lead us to infer the quiet and contemporaneous formation of 

 the horizontal beds of nodular limestone with which they 

 are associated, and in truth this is put beyond a doubt from 

 the circumstance that the Septaria have frequently been 

 found to include fossils similar to those occurring in the 

 body of the clay. From these analogous cases, and the con- 

 sideration of others I have thought it unnecessary to de- 

 tail, I have been led to consider the Indian kankar beds 

 as being formations " in situ," and nearly contemporaneous 

 in their origin with the beds of calcareous clay with which 

 they are associated. This remark applies to the kankars of 

 those localities where no proofs of the previous existence or 

 operation of calcareous springs can be detected, and where 

 the facts oppose the idea of transporting forces having been 

 in action. 



Conceiving then that the kankar beds are actually " in 

 situ," some explanation is still required to account for the 

 great difference between them and their associated strata ; 

 and here it must be fully acknowledged that our informa- 

 tion is still but very limited, and that our reasoning must, 

 as before, be chiefly from analogy. It has been already 

 remarked, that kankar appears to be one of a class of sub- 

 stances formed under similar circumstances, and that if 

 we could throw any light on the formation of one of these, 

 we might thus gain an insight into that of the others. Now 

 it is known from experiment that if a mechanical mixture of 



* Cuvier's Theory of the Earth. English edition. 



