234 THE EARTH MADE READY FOR MAN 



land. Well, away back in those times when the giant 

 trees grew, these creatures commenced to walk out 

 of the water and onto the seashore. They were the 

 same kind of animals as the frogs, and they could live, 

 too, in the water or on the land, but they were as 

 much larger than toads or frogs as you can think or 

 imagine. Sometimes they walked on the sea beach 

 and left their great footprints in the wet sand and 

 mud. 



And what do you suppose happened to those foot- 

 prints? They were preserved for us in the sandstone, 

 and now make some of the pictures in nature's book 

 of the rocks. 



Sometimes in among the footprints there are rain- 

 drop marks — big ones — showing that there was a 

 hard shower with great, heavy drops. But the queer 

 animals did not care. They could live in the water 

 if they chose, so they walked right along and did not 

 try to get under cover. 



Sometimes in the slate that used to be the muddy 

 flats of those days there are marks that we call sun 

 cracks. Have you ever noticed those queer cracks 

 on the surface of dried mud? The same shaped 

 cracks were made in the drying mud long ago, and 

 when we see them in the rock we know that the sun 

 came out bright and hot, and dried the mud quickly. 



After the amphibians had had their rule in the 

 water and on the land, reptiles came, — the strange, 

 huge lizards that would make even the dragons of 

 fairy tales seem quite ordinary. These reptiles lived 

 by the side of the marshes and walked about on the 

 exposed mud flats. They may have gone down at 



