On a Piece of Chalk 89 



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 5 

 countries we now call south-east England, France, Ger- 

 many, 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, 10 

 more than a thousand feet thick. I think you will agree 

 with me, that it must have taken some time for the skele- 

 tons of animalcules of a hundredth of an inch in diameter 

 to heap up such a mass as that. I have said that through- 

 out the thickness of the chalk the remains of other ani- 15 

 mals 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 20 

 that these animals have lived and died when the place 

 which they now occupy was the surface of as much of the 

 chalk as had then been deposited; and that each has been 

 covered up by the layer of Globigerina mud, upon which 

 the creatures imbedded a little higher up have, in like 25 

 manner, lived and died. But some of these remains prove 

 the existence of reptiles of vast size in the chalk sea. 

 These lived their time, and had their ancestors and de- 

 scendants, which assuredly implies time, reptiles being of 

 slow growth. 30 



There is more curious evidence, again, that the process 

 of covering up, or, in other words, the deposit of Globi- 

 gerina skeletons, did not go on very fast. It is demon- 

 strable that an animal of the cretaceous sea might die, 



