3S Watson and Powell — Age of Virginia Piedmont Slates. 



In several sections, especially those of Occoquan and Qnantico 

 creeks, occasional steep southeasterly dips are observed. The 

 general structure of the rocks suggests a series of closely com- 

 pressed folds, probably of the isoclinal type. 



The slates are not lithologically alike for the entire thickness 

 of the belt in any section measured, but a variety of types 



Fig. 3. 



Fig. 3. Alternating light- and dark-gray slates, about % mile S.E. of 

 Occoquan village, on Occoquan Creek. The position of the slates is ver- 

 tical. Some beds are tufaceous. 



Fig. 4. 



Fig. 4. Alternating light- and dark-gray slates, partly tufaceous, show- 

 ing a steep dip to the southeast. About y z mile S.E. of Occoquan village, 

 on Occoquan Creek. 



