Watson and Powell — Age of Virginia Piedmont Slates. 41 



Fig. 7. 



Fig. 7. Dike of igneous rock intruding slates parallel to the cleavage, 

 ■west of Dumfries on Quantico Creek. 



Fig. 8. 



Fig. 8. Granite-gneiss exposed in Austin Run near contact of the slates 

 on the northwest. 



