Chalk Cliffs near Dover . c l\ 
every instance, examination proved that the flint of each bed so 
exposed, was connected together : not that it formed one plane 
surface; but, though varying in thickness from 6 to 18 inches, the 
flint would, if It could be taken off* whole, have exhibited occasional 
cavities, which, collectively, would have formed but a small pro- 
portion of the whole surface. A man who had been employed on 
this work during eighteen years, , assured me that he had always 
observed the same fact* 
Among the fragments of flint thrown aside, I noticed many 
having surfaces,, evidently the consequences of fracture, that were 
opake and white ; and as, on breaking these flints anew, they were 
always black internally, it seemed possible that this whiteness and 
opacity might be owing to the disintegration of the fractured surface 
by long exposure. The examination, however, of the beds of 
flint in these blocks of chalk, shewed the futility of this supposition;; 
for the flint then exposed for the first time, was found to be cracked 
through in several places, from one cavity to the next : and the 
fractured surface was in every instance, more or less white and 
opake. Such a fracture seems explicable only by the supposition 
of a contraction having taken place in the flint while in its natural 
position. Nor does it appear to me at all improbable that a con- 
traction had actually taken place. Flint newly disengaged from 
its natural bed, is much more brittle, requires a much lighter blow 
to break it, than flint that has been long exposed.* This may 
perhaps be owing to the moisture or water belonging to the flint 
in its natural state, but which it loses in great measure by the joint 
action of the air and sun. 
* The flint gravel used for mending the roads round London, is in some places provi- 
dently taken from the pit some time before it is wanted, and exposed to the action of the 
air and sun: for this practice the alleged reason is, that it hardens; which, probably is-- 
the fact.. 
