20 ON A PIECE OF CHALK j 



one of them inhabited fresh water the collateral 

 evidence that the chalk represents an ancient sea- 

 bottom acquires as great force as the proof 

 derived from the nature of the chalk itself. I 

 think you will now allow that I did not overstate 

 my case when I asserted that we have as strong 

 grounds for believing that all the vast area of 

 dry land, at present occupied by the chalk, was 

 once at the bottom of the sea, as we have for any 

 matter of history whatever; while there is no 

 justification for any other belief. 



No less certain it is that the time during which 

 the countries we now call south-east England, 

 France, Germany, Poland, Russia, Egypt, Arabia, 

 Syria, were more or less completely covered by a 

 deep sea, was of considerable duration. We have 

 already seen that the chalk is, in places, more 

 than a thousand feet thick. I think you will 

 agree with me, that it must have taken some 

 time for the skeletons of animalcules of a 

 hundredth of an inch in diameter to heap up 

 such a mass as that. 1 have said that through- 

 out the thickness of the chalk the remains of 

 other animals are scattered. These remains are 

 often in the most exquisite state of preservation. 

 The valves of the shell-fishes are commonly 

 adherent; the long spines of some of the sea- 

 urchins, which would be detached by the smallest 

 jar, often remain in their places. In a word, it is 

 certain that these animals have lived and died 



