GEOLOGICAL SOCIETY OF PENNSYLVANIA. 



301 



Stone appears to have been acted upon by running water, 

 and by fragments kept in motion by the fluid ; cavities 

 frequently occur in the rock which resemble those pots 

 occasionally observed elsewhere, and which have been 

 been formed by constant agitation of mineral particles, 

 kept in motion by the fluid. Veins of quartz traverse 

 the beds, and much isolated quartz rock is seen on the 

 surface of the ground. The quartz is sometimes a milky 

 quartz, at other times it has the appearance of a fine grit, 

 assuming various forms. In the environs of Winchester 

 the limestone is more silicious than usual. There are 

 seams of this rock that contain a sufficiency of insoluble 

 matter to render the lime obtained eminently hydraulic, 

 and of these some are coloured almost black with carbo- 

 naceous matter. Near Shepherdstown, on the river 

 Potomac, hydraulic lime is prepared and used in the 

 country in the construction of canals, &c. Not far from 

 Charlestown, and near the village of Smithfield, fine 

 marbles are quarried, but to a small extent, and only for 

 the uses of the vicinity. 



The blue limestone breaks into fragments too small to 

 be used extensively for ornamental purposes, or where 

 regularity in large pieces is an object. 



BLUE RIDGE. 



The river Shenandoah, which in the original Indian 

 language means river of clear water, bathes the western 

 foot of this chain, which has a parallel direction with the 

 Alleghanies. The general dark appearance of all high- 

 lands viewed at a distance, aided with a little imagina- 

 tion, may make the received appellation, applied to 

 these mountains, appropriate. The western declivity of 

 this chain is much more precipitate than its eastern in- 

 clination. 



The volcanic action (if we admit such a power to have 

 been exerted in this case), that at some former period 



