71 



rocks. A careful investigation of the numerous large quartz veins 

 ranging along the valley between the South-west mountain and Blue 

 Ridge, becomes in this point of view a matter of great importance ; 

 and should the auriferous character be found pervading these veins, 

 as is not improbably the fact, the extent and value of the gold re- 

 gion of the state will scarcely have a parallel upon the globe. 



OF THE MICACEOUS AND GARNET SLATES, SILICIOU3 SLATE, WHETSTONE 

 BEDS, ROOFING SLATE, STEASCHIST, IRON ORE, &C OF THE REGION WEST 

 OF THE GNEISS. 



In pursuing the line indicated in the section, after leaving the 

 gneiss and hornblende slate, which extend some distance above Co- 

 lumbia on both sides of the James river, the rocks met with are 

 chiefly various kinds of slates and schists, penetrated occasionally 

 by the veins of auriferous quartz already described, and furnishing 

 materials for building and other uses. Analogous beds are also met 

 with in the regions north-east and south-west of that here referred 

 to — ranging through the state in a belt comprehending what is usu- 

 ally termed the gold region, and bounded on its western side by the 

 narrow belt of limestone lying east of the base of the South-west 

 mountain. The descriptions about to be given of these various 

 rocks and other materials, though founded upon an examination of 

 them as they occur in Buckingham, Fluvanna, Louisa, and one or 

 two other counties in the range, will obviously be applicable, with 

 some modifications, to the corresponding beds occurring in other 

 portions of the same belt. 



MICACEOUS GARNET SLATE, OR BIRDSEYE MAPLE SLATE. 



After leaving the gneiss and hornblende slate a little below Bremo, 

 we come upon heavy vertical beds of a micaceous slate, in which 

 are multitudes of half developed garnets, and sometimes crystals of 

 cubical pyrites — giving to the surface of the rock the appearance of 

 numerous knots, around which the fibres of the stone are beautifully 

 curved, so as closely to resemble the shading of the birdseye maple ; 

 and hence, in the absence of any specific designation, the one above 

 used may be considered as appropriate at least for ordinary pur- 

 poses. This rock has the lustre and colour of plumbago, and evi- 

 dently contains much mica. It possesses considerable hardness, and 



