PRINCIPLES OF GEOLOGY. 29 



of agitated and of tranquil waters, mechanical aggregates, sedimentary 

 deposits, and chemical precipitates, in frequent repetition. This cir- 

 cumstance, combined with the facts relating to organic remains, teaches 

 us, that during a long period, the sea flowed rich in living beings 

 over rocks which contain no reliques of life. At times tranquil, 

 at intervals tumultuous, this ocean, perhaps of elevated temperature, 

 even in the northernmost regions, varied its deposits at different periods, 

 yet preserved among them a general conformity of arrangement, from 

 the oldest to the most recent, and a similarity over large regions. 

 The aquatic animals and other remains, which are entombed in the earth, 

 exhibit a long series of beings, whose origin dates from some of the 

 earliest strata, and whose forms, differing according to the antiquity of 

 the rocks, successively come nearer and nearer to the modern produc- 

 tions of the land and the ocean. During this process, at intervals, vege- 

 table forests swept into estuaries, or lakes, furnished the materials of 

 coal, and the intermitting action of submarine volcanoes frequently 

 broke the consolidated strata, and formed basaltic and other overlying 

 rocks. At times, too, more violent exertions, probably of the same 

 cause, uplifted groups and ranges of mountains with great disruption and 

 dislocation. Operations of the same kind are to this day continued, but 

 so feebly,* that we commonly speak as if the causes which concurred to 

 produce the crust of our planet, had ceased to exist. They appear, how- 

 ever, to have been gradually weakened, and when the last series of the 

 secondary beds, partly marine, partly lacustrine, was deposited, a large 

 portion of pre-consolidated rocks became tenanted by land animals. But 

 again the waters returned and overflowed the inhabited world ; removed 

 rocks, excavated vallies, and destroyed the terrestrial inhabitants, from 

 whose anatomical construction, as displayed in their remains, it may be 

 inferred that the antediluvian face of the earth was like our own, diversi- 

 fied by lakes, and forests, and mountains. 



This transient flood retires from the desolated continents ; again the 

 forest is clothed with foliage ; birds fly in air, and animals roam the 



- Absumptis per longum viribus a;vum. 



