18 BULLETIN OF THR NATUKAL HISTOEY SOCIETY. 



plants were preserved. Finally the sea swept over it and 

 destroyed its verdure. Great rugged hills rose in the interior, 

 and from time to time, here and there in the neighboring 

 country, volcanoes, emerged and submarine, poured out their 

 lava, ashes and mud over the surrounding tract. The forest 

 and fern growth was swept away, not to return until the 

 Carboniferous age. 



It would tire you were I to attempt to draw a sketch of 

 the physical condition of this region in later geological time, 

 or to indicate the climatic changes that have supervened, but 

 those which I have hastily sketched for the Cambrian and 

 Devonian ages may interest you, as they are attested by rocks 

 which underlie your city, and proved by the animal and plant 

 remains its rocks contain. 



