22 A Home for Life 



feet above the sea, lav a cake of the carboniferous 

 rocks called millstone grit. This little remnant on the 

 highest ground of the district demonstrated that a 

 sheet of millstone grit once stretched over that remote 

 part of the island, and may have extended much 

 farther westward over tracts where the Atlantic now 

 rolls." But no matter how strata have been upheaved 

 and broken, folded and piled and thrust over one 

 another, no one doubts the continuous operation of 

 natural factors more or less similar to those seen in 

 operation to-day. 



What a fine vision Tennyson had of the age-long 

 breaking-down and building-up, disintegration and 

 reintegration ! — 



There rolls the deep where grew the tree. 



O earth, what changes hast thou seen ! 



There, where the long street roars, hath been 

 The stillness of the central sea. 



The hills are shadows, and they flow 



From form to form, and nothing stands ; 

 They melt like mist, the solid lands ; 



Like clouds they shape themselves and go. 



§12. Making a Home for Life. 



The earth was for long ages far too hot to be ten- 

 anted by any living creatures like those we know, and 

 there is no use in talking of any others. Only the 

 mythical salamander could have lived in the earth of 

 long ago. But there was gradual cooling and the 

 formation of a more or less substantial crust. 



In his illuminating Origin of the Earth (Chicago, 



