374 THOMAS L. WATSON 



Structural Features of the Granites. 

 Megascopic structures. 

 Joints. 

 Slickensides. 

 Schistosity. 

 Basic inclusions. 

 Microscopic structures. 



Granophyric structure. 

 Micropoikilitic structure. 

 Intersecting Dikes and Veins. 

 Basic igneous dikes. 

 Granite dikes. 

 Pegmatite and aplite. 

 Quartz veins. 

 Relations between the Joints of the Granite and Dikes of Basic Igneous 



Rocks. 

 Age Relations of the Dikes of Basic Igneous Rocks. 



INTRODUCTION. 



The following paper is based on a study of the granites and 

 gneisses of North Carolina during the past field season, while I was 

 engaged on the State Geological Survey in a field study of these rocks. 

 The economic report treating of the granites has been prepared and 

 will form a part of a general report on the building-stones of North 

 Carolina to be published by the State Survey. A general summary 

 setting forth the more important points in the petrography and struct- 

 ure of these rocks is offered in the present paper as a separate contri- 

 bution. 



DISTRIBUTION OF THE GRANITES. 



North Carolina is divisible naturally into three principal physio- 

 graphic provinces, which, named in order from east to west, are: the 

 Coastal Plain, the Piedmont Plateau, and the Appalachian Moun- 

 tains. These form a part of the continuation of the same provinces 

 to the north and south of North Carolina; and they observe approxi- 

 mate parallelism with each other and with the general trend of the 

 coast line of the southeastern Atlantic states. The granites of North 

 Carolina are distributed over parts of each of these three provinces; 

 the areas being fewer and smaller over the Coastal Plain region, and 

 more numerous and larger over the Piedmont Plateau region. Gran- 



