26 ILjLUSTRATIONS OF THE 



from one another, afford an argument of the 

 'fame kind ; fince the flinty matter, if it had been 

 carried into the chalk by any folvent, muft have 

 been depofited with a certain degree of unifor- 

 mity, and would not now appear colle^ed into 

 feparate mafles, without any trace of its exift- 

 ence in the intermediate parts. On the other 

 hand, if we conceive the melted flint to have 

 been forcibly injeded among the chalk, and to 

 have penetrated it, fomewhat as mercury may, 

 by prelTure, be made to penetrate through the 

 pores of wood, it might, on cooling, exhibit the 

 fame appearances that the chalk-beds of Eng- 

 land do actually prefent us with. 



The iiliceous pudding-ftone is an inflance 

 clofely conneded with the two laft ; in it we 

 find both the pebbles, and the cement which 

 unites them, confifling of flint equally hard and 

 confolidated ; and this circumftance, for which 

 it is impoffible to account by infiltration, or the 

 infinuation of an aqueous folvent, is perfectly 

 confiflent with the fuppofition, that a ftream of 



melted flint has been forcibly injeded among a 

 mafs of loofe gravel. 



21. The common grit, or fandflone, though 

 it certainly gives no indication of having pof- 

 fefled fluidity, is flrongly expreffive of the ef- 

 feds of heat. It is fo, efpecially in thofe in- 

 ftances where the particles of quartzy fand, of 



which 



k_r 



