JBOMA.IN IX. ANOMALOUS. 



commonly employed for the purpose of paving 

 court-yards of houses, and the streets of small 

 towns. Common gravel is too familiar to need 

 any description. Pebbles of the smallest dimen- 

 sions constitute coarse sand. 



" The gravel immediately round London ap- 

 pears to consist almost entirely of the black flint 

 met with in the neighbouring chalk strata : the 

 pebbles are in general very uniformly worn, and 

 have to a greater or less extent lost the charac- 

 teristic black colour of the flint, from which 

 they are derived ; but sufficiently correspond 

 with it to shew the identity of their nature. 



" The gravel round about Windsor and Maid- 

 enhead consists also, in a great measure, of the 

 flint of the surrounding chalk-hills ; very much 

 discoloured, but not much worn. It appears, 

 however, that that part of this gravel which is 

 nearest the surface is not of the nature of flint, 

 but in its texture resembles a highly indurated 

 sand-stone: and it is observed that these pebbles 

 are much larger than the flint pebbles ; and, 

 though considerably harder, are much more 

 uniformly rounded. They have probably, there- 

 fore, been conveyed from a greater distance ; 

 and judging from their relative situation, for 

 they are found nearest the surface, they have 

 been deposited more recently than the flint. It 



