ELISHA MITCHELL SCIENTIFIC SOCIETY. 7 1 



the wheels settles among the fragments below and consoli- 

 dates the entire mass. For this reason, in many cases, it 

 has been fonnd to be good policy to mix a considerable 

 quantity of limestone with some siliceous and igneous 

 rock, which though hard and tough does not consolidate 

 readily. 



Gravel and Sand are not used in the construction of 

 stone roads as formed by Macadam and Telford, except as 

 an excellent foundation, for which purpose they possess a 

 very great value; and as a binding material, in small 

 quantities, they are sometimes spread over the road surface 

 between the layers of crushed stone. When used in this 

 latter connection, however, the gravel must be quite free 

 from round pebbles. Gravel is, however, used extensively 

 in the construction of what are termed gravel roads; where 

 there is no attempt at macadamizing the roads, but where 

 the gravel itself is spread uniformly over the surface of a 

 foundation road-bed which has been properly shaped and 

 drained. Gravel like that which occurs so abundantly in 

 many Northern States, where glaciers existed, is not found 

 in North Carolina. But river gravels are found in a num- 

 ber of our counties; and, as suggested above, in the middle 

 and western counties there are to be found in places decayed 

 siliceous granite and gneiss which, though not suited for 

 mixing with crushed stone in macadamizing roads, yet 

 will be found to serve a useful purpose as a foundation for 

 the broken stone on clay roads, and also as a top dressing 

 on clayey dirt roads. 



DISTRIBUTION OF ROAD MATERIALS. 



A line drawn from Gaston to Smithfield, Smithfield to 

 Cary, and from Cary to Wadesboro, separates the State into 

 two general and well-marked divisions, the eastern of 

 which may be called the Coastal Plain region, and the 

 western may be termed Piedmont and Mountain regions. 



