FRANKLIN COUNTY. 629 



of scores, perhaps of hundreds of years. The reason why teeth are 

 found so much more abundantly than other portions of the skeleton is 

 that they are among the few portions that are thoroughly mineralized, 

 and consequently able to resist decay. The framework of the shark is 

 chiefly cartilaginous. These facts help us to understand the origin of 

 the layer in the Corniferous limestone which we are now considering. 

 The fact, itself, is one of great interest. Hardly had fishes appeared in 

 the seas before they took almost complete possession of them. A bone 

 bed made of their remains, is one of the earliest facts in their history, 

 in the European rocks, as it is in our own. 



IV. ECONOMICAL GEOLOGY. 



A few additional statements will here be made in regard to the useful 

 applications of the Corniferous limestone. 



These applications are two in number, and have been already inci- 

 dentally treated. The formation furnishes building stone and lime. The 

 supply in Franklin county is indefinitely great. It can be counted by 

 the square mile, in areas that require very little stripping and where 

 railroad transportation can be made easily available. The abundance of 

 the supply is best understood when it is remembered that the quarries 

 are never less than twenty feet in depth, and that often thirty leet of 

 stone, almost every foot of it available for some purpose, lie above the 

 river level. Assuming the specific gravity of the limestone to be 2.5, 

 an acre, worked to a depth of 25 feet, yields 85,000 tons, and a square 

 mile yields under the same conditions 64,400,000 tons, an amount which 

 can be readily expressed in figures, but of which we can form no ade- 

 quate conception. 



The character of the building stone furnished remains to be described. 

 Very much can be said in its favor. It is a dense, compact limestone, 

 with a specific gravity exceeding 2 5. It is very strong and can bear all 

 of the burdens which architecture demands. A number of the courses 

 yield cutting stone that is, the stone lies in the courses in pieces of several 

 hundred feet square and can be raifed in blocks large enough to answer for 

 sills, window-caps, platforms and similar uses. When the stone comes out 

 in this way, it commands four times the price that building stone, i. e., the 

 stone that is raised in blocks too small for such applications, brings. It 

 is generally worked with sufficient ease, though some courses that are 

 otherwise suitable have too large a proportion of flint. Its color is very 

 satisfactory, all the shades being cheerful and pleasant to the eye, and 

 sufficient variety being afforded by judicious selection. It receives 

 ornamentation to good advantage, moulding and other relief showing 



