212 THE EARTH MADE READY FOR MAN 



upon the land. These particles had accumulated far 

 out upon the ocean floor beyond the thick beds of 

 sand and clay. Can you guess what they could have 

 been? 



You remember we spoke of those countless, im- 

 perceptible creatures that lived in tiny shells in the 

 ocean. These slowly sifted down throughout those 

 long, long ages, and settled upon the ocean floor. 

 One would hardly think there would be enough of 

 them to make a thick mass of rock. But so it was, — 

 age after age they collected in great quantities upon 

 the ocean floor, and in the course of time they 

 were pressed into solid rock called limestone and 

 marble. 



You have seen many things made of marble, — 

 statues, table tops, mantel-shelves, and the stairs 

 and floors of large buildings. The glistening white 

 marble of which statues and table tops are made is a 

 crystalline form, made by the underground water 

 carrying a mineral in solution. 



Other kinds of marble are made under the floor of 

 the ocean by the help of those drops which soak 

 through into the mass of accumulated shells. The 

 pressure and the water and the heat make marble of 

 the mass of shells, because in them are found the 

 same mineral that the underground water carried in 

 solution to make the glistening white marble. In 

 some kinds of limestone we can see many of the little 

 shells quite plainly. There they lie embedded in the 

 stone, perfectly preserved. 



How marvelous it is that those pretty Httle shells 

 should be preserved through all these ages. They 



