126 SKETCHES OF CREATION. 



where- it has been studied by Professor C. H. Hitchcock, and 

 Mr. Billings, of Montreal. 



Thus closed the Silurian Age. At the east the rocks of 

 this age are marked off from the great mass of overlying 

 Devonian strata by the interposition of a conglomerate — 

 the " Oriskany Sandstone," which signalizes the confusion 

 attendant upon the change of scene. At the West, how- 

 ever, this formation is generally wanting ; and we find the 

 limestones of the Corniferous group resting upon those of 

 the Niagara group, except where the Salina rocks inter- 

 vene. The Corniferous is a most important limestone mass 

 throughout the West. It merges generally into the cal- 

 careous portion of the overlying "Hamilton" strata, and 

 forms a landmark in the topography of the country no less 

 than in the series of rocks. In this limestone, quarries are 

 worked from Western New York, in the latitude of Buffalo, 

 through the contiguous peninsula of Canada to Sandusky 

 and Columbus, Ohio, Monroe and Mackinac, Michigan, and 

 multitudes of points in Indiana, Illinois, and Iowa. These 

 limestones, like all others, were accumulated in the bottom 

 of deep and quiet seas. Each successive floor has been the 

 home of moving myriads of sensitive forms. Every layer 

 of rocks has been the cemetery of many generations. Life 

 teemed especially in calcareous and placid waters. Such 

 were those of the Corniferous period ; and these limestones 

 are stocked with the relics of ancient dynasties — great and 

 small, powerful and weak, in one wide burial confusedly 

 blent. Nor yet had nature dispensed with the pattern of 

 the trilobites. Encrinites were still in vogue, and ortho- 

 ceratites, and all the various phases of univalve and bivalve 

 creation. And here — here first dawned upon our planet an 

 animal with a backbone — a mere fish, but yet the basis on 

 which artist Nature has moulded successive models till the 

 form of man shone forth, and the Omniscient was satisfied 



