342 BF- CACHES IN THE INNER 



ment you leave the mountains skirting the Potomac and 

 the Shenandoah on their eastern or atlantic side, the 

 minerals are of a different character. Immediately at 

 their bases, and at the banks of these respective rivers, 

 the strata becomes shistose. The streams pass by islands, 

 and roll over beds of slate. The strata lie, where they 

 have not been deranged, at angles of from thirty-three 

 to forty-five degrees from the horizon ; and their dip or 

 inclination, particularly in the channel of the Pbtomac, 

 is from N. W. to S. E. Suddenly as you pass to the Vir- 

 ginia side, the slate rises with a rough, craggy, and pic- 

 turesque front. 



Between the margin of the water and the foot of this 

 elevation, stand the shops where the muskets, pistols, and 

 rifles are manufactured for the United States. At this 

 commodious spot, the water for turning the wheels and 

 giving force to the machinery is conducted through a 

 canal or raceway about a mile in length. In several 

 places, this passage has been dug through layers of slaty 

 rock. A principal part of the stone-work consists of the 

 same material ; for although it does not split into forms 

 fit for covering houses, it may be separated into slabs 

 and fiags fit for walls and floors. Here it is rare to be- 

 hold any mixtures of quartz ; yet small parcels may be 

 found. No other mineral abounds. Slate prevails every 

 where. The heights from which the traveller surveys 

 the sublime and picturesque scenery hereabout are slate. 

 In short, whether wells are opened for water, founda- 

 tions for buildings, or graves for the dead, parcels of 

 shistus are raised with the spade. And from the lowly 

 channel to the pinnacle where the powder magazine 

 stands, the solid body of the mountain is brittle shist. 

 In some places the layers appear to have been disturbed ; 

 for some of them are cracked through perpendicularly: 



