2 4 THE HISTORY OF CREATION. 



sea, the deposited layers of mud get into contiaually deeper 

 and quieter water, where tliey can become condensed into 

 stone undisturbed. But when, on the other hand, the 

 gromid slowly rises, the newly-deposited layers of mud, 

 which enclose the remains of plants and animals, again im- 

 mediately come within the reach of the play of the waves, 

 and are soon worn away by the force of the breakers, 

 together with the organic remains which they enclose. For 

 this simple but very impoiiant reason, therefore, abundant 

 layers, in which organic remains ai-e preserved, can only 

 be deposited during a continuous sinking of the ground. 

 When any two different formations or strata, lying one 

 above the other, correspond with two different periods of de- 

 pression, we must assume a long period of rising between 

 them, of which period we know nothing, because no fossil 

 remains of the then living animals and plants could be pre- 

 served. It is evident, however, that these periods of 

 elevation, which have passed without leaving any trace be- 

 hind them, deserve a no less careful consideration than the 

 greater or less alternating periods of depression, of whose 

 organic population we can form an approximate idea from 

 the strata containing petrifactions. Probably the former 

 were not of shorter duration than the latter. 



From this alone it is apparent how imperfect our records 

 must necessarily be, and all the more so since it can 

 be theoretically proved that the variety of animal and 

 vegetable life must have increased greatly during those very 

 periods of elevation. For as new tracts of land are raised 

 above the water, new islands are formed. Every new 

 island, however, is a new centre of creation, because the 

 animals and plants accidentally cast ashore there, find in 



