GEOLOGICAL SOCIETY OF PENNSYLVANIA. 



317 



ersed and studied the same stratification in an oblique 

 direction, between James River and the Rappahannock, 

 we are acquainted with, and in fact have illustrated in 

 pi. 16, fig. 2, the geological character of 40 miles more, 

 where those rocks are prolonged till they intersect the 

 section we are describing. 



Thickness of primitive rocks passing be-- 

 tween the parallels of Richmond and 

 Fredericksburg, com'se of strata north 

 east, not less than .... 15 miles 



I. Primitive class, west of Fredericksburg, 

 at right angles to the direction of the stra- 

 tification, ...... 7 " 



The Gold Belt, 10 " 



II. Class of altered and amphibolic rocks, 

 and intermixed beds, extending to the 



west side of the Blue Ridge, . . 30 " 

 in. Transition beds, average dip 40° for 



nine miles, .... 6 " 



68 " 



We have thus, in a breadth of 120 miles, the enor- 

 \ mous thickness of 68 miles, the whole mass of which de- 

 clines in one uniform direction. 



The fourth section, to which the present article has 

 reference, and shown in plate 18, is a detailed portion of 

 the Virginia Gold Belt, near the Rappahannock. Hav- 

 ing studied the position of the auriferous veins in this 

 place, with more minuteness than in most others, and 

 with professional objects, we are permitted by the pro- 

 prietors of the mines to communicate to the Geological 

 Society the section which was constructed from those 

 examinations. 



It comprises only about a twentieth part of the breadth 

 of the Gold Belt, and the rocks partake of the prevailing 

 character of that region; consisting of talcose slate, chlo- 



