Mr. Webster on the Strata lying over the Chalk. 239 



If it be asked what has become of the supposed matrix in which 

 these flints were formed, and how could strata so considerable as 

 they must have been, have disappeared without leaving a single 

 trace of their existence ? It may be answered, that the difliculty is 

 exactly the same in supposing them to be derived from the chalk ; 

 for no remains of this rock are to be found with these pebbles ; and 

 it is' equally impossible to discover what has become of the chalk 

 that must have belonged to the flint pebbles that are undoubtedly 

 derived from it. 



But when we see rolled pieces of granite, of quartz, and other pri- 

 mitive rocks, occurring frequently in the alluvium of this part of 

 the country, though so far removed from the places where these 

 substances are in situ, we feel so assured of the extensive nature 

 and violent action of the cause that has occasioned such destruction, 

 that we need not wonder if many strata have been reduced to a 

 state of impalpable division, and have been scattered over the surface, 

 so that not a fragment remains entire ; or have been deposited in the 

 depths of the ocean, where they may have formed new combina- 

 tions that may at some distant period be exposed to view, and affbrd 

 matter for the contemplation of future generations. The Hertford- 

 shire pudding-stone has been already mentioned. It is composed 

 of these concentric pebbles united by a granular quartz, and is 

 most abundant in the neighbourhood of St. Alban's, but is found 

 in many other places above the chalk. It occurs in large irregular 

 masses in the gravel ; but I am not aware that it exists any where 

 in an extensive bed in situ. 



To account for the appearance of this pudding-stone we have 

 to suppose, Isr, the existence of a stratum superior to the chalk, 

 containing under some form, the substance of which these pebbles 

 are composed. 2d, the agency of some power capable of breaking 



