74 



THE EAETH. 



and must have been the original sand of the sea-bottom 

 before the chalk was deposited on it. These seas must have 

 been the residence of a vast number of reptiles, for the gault 

 contains an enormous number of nodules of what appears to 

 be stone, but which upon closer examination, prove to be 



FIG. 26. NAUTILUS INEQUALIS. 



coprolites, or portions of the excrement of those creatures 

 partly fossilised, but still retaining phosphate of lime enough 



FIG. 27. ORGANISMS FROM CHALK. 



to render them valuable manure, and these like the coal- 

 after being buried in the earth for thousands of years, are 



