THE CHALK DOWNS. 207 



vegetable mould a thick layer of loose nodules 

 but slightly abraded, and in no instance worn into 

 the state of boulders, pebbles, or gravel. The 

 surface of the chalk covered by the flints is fur- 

 rowed and waterworn, like that of the exposed 

 chalk along the coast. From the state of the 

 loose flints, it is evident, that although they must 

 have been washed out of pre-existing strata, 

 they have not been subjected to the action of 

 the waves for any considerable period, like the 

 materials of the existing sea-beach. For when 

 masses of the chalk cliffs fall within reach of the 

 billows, the exposed portions of the flints are com- 

 pletely rounded before the nodules are loosened 

 and detached from the parent rock ; and so soon 

 as the flints are liberated by the wearing away of 

 the surrounding chalk, they are quickly driven 

 against each other and broken, and the fragments 

 ground into pebbles, gravel, &c. ; in this man- 

 ner are formed the shingle and sands that accumu- 

 late along the sea-shore. 



From the state of the down-flints, it is there- 

 fore obvious that the deposits whence they were 

 derived, must have been less consolidated than the 

 present chalk, and have admitted of the removal 

 of the calcareous materials, and the consequent 

 extrication of the siliceous nodules from the rock, 



