yO JOURNAL OF THE 



North Carolina, and is an excellent road material. The 

 v-arieties which are finer in grain, and those having the 

 larger proportion of the black mineral known as horn- 

 blende and are consequently of darker color, are best 

 adapted for this purpose. 



Granites vary considerably, both in quality and appear- 

 ance, and in their value as road material. Those which 

 are very coarse in grain, containing large and numerous 

 crystals of feldspar, are, as a rule, more easily crushed and 

 decay more rapidly, and should not be used in road con- 

 struction when better materials are available. Those 

 which contain a large proportion of mica split and crush 

 more easily into thin flakes and grains, and for this reason 

 are also less valuable. Those varieties which are of fine 

 tjrain and contain an admixture of hornblende are best for 

 road purposes. 



Gneiss^ which has the same general composition as 

 granite, also varies very greatly in its quality and adapta- 

 bility to road building. It usually has the appearance of 

 being somewhat laminated or bedded, and when the layers 

 are thin and the rock shows a tendency to split along these 

 layers it should be discarded for road purposes. In addi- 

 tion to this, the statements made above with reference to 

 the granites will apply also to gneiss. 



Liinesione suitable for road purposes is not an abundant 

 rock in North Carolina, but it is found in a few of the 

 eastern and a few of the western counties. It is a rock 

 which varies very greatly in character, from the hard, fine- 

 grained, compact magnesium limestone, which is a most 

 excellent material for the Macadam and Telford roads, to 

 the porous, coarse and partially compact sliell-rock of 

 recent geological formation, which is less valuable mate- 

 rial. Practically all limestones when used as road material 

 possess one valuable qualification, that of "binding''; the 

 surface material which becomes ground by the action of 



