i6o THE OCEAN 



creatures existed in the most ancient times and 

 by innumerable collections and careful study, 

 scientists and geologists have classified the 

 various beasts, fishes, insects and other crea- 

 tures which lived in those days and can trace 

 their ancestors and descendants, and even 

 know fairly well how the strange creatures 

 really appeared in life. It is an easy matter to 

 tell which forms lived first, for, of course, each 

 layer of rock covers layers that were made 

 before it and thus the deeper the layer of rock 

 the older the record and the more ancient the 

 creatures which made the tracks. 



These are only one kind of pages from the 

 story of the sea and beneath the waves the 

 chapters are also being written. Here the 

 dead and dying animals are constantly accum- 

 ulating and are being covered with fine mud, 

 ooze and sand, in places forming deposits 

 many feet in depth. Just as, through the vast 

 lapse of time which has passed since animal 

 life first appeared in the sea, the mud and sand 

 of the shores have been transformed to sand- 

 stone and shale, so the ooze and dead shells at 

 the bottom of those ancient seas have been 



