222 Geology of the Country between 



reous deposit, and interposed between the limerock and graywacke. 

 It is extremely interesting, as furnishing a beautiful ornamental mar- 

 ble that will amply repay the labor of polishing. The Catoctin ridge 

 next succeeds, and presents very evidently a closer approximation to 

 the primitive series, than is to be met with at any other point west of 

 the primitive region of Baltimore. Adjoining the Potomac marble, 

 there occurs a talcoseish looking slate often traversed with siliceous 

 reins and alternating with arenaceous strata. The whole formation 

 is colored with chlorite, sometimes very deeply. That mineral is 

 often found in disseminated masses ; epidote is also quite common, 

 and a little farther north, genuine serpentine is found. We have 

 here, as in all other parts of the world, searchers after gold and silver, 

 to whom the copper and iron pyrites, abundant in these rocks, have 

 proved no small source of disappointment. Should the talcose slate 

 hereafter be found to exist extensively in this region, a well directed 

 search for gold might be successful. Descending the Catoctin moun- 

 tain, we enter Middletown valley, a comparatively narrow intervale, be- 

 tween the last named mountains and the Blue ridge. I have colored the 

 section to indicate the occurrence of limestone in this valley, upon the 

 authority of others. There can be but little doubt that it is found there, 

 although I have not seen it myself. West of Middletown we meet an- 

 other deposit of graywacke, constituting the south mountains of Mary- 

 land and Pennsylvania, known as the Blue ridge, where it crosses Vir- 

 ginia. Leaving the quartzose rocks of this range, we enter the extensive 

 valley in which Hagerstown is situated, and again find the limerock 

 showing its bassetting edges. It here agrees perfectly with that of 

 Frederick valley, and continues until approaching the North moun- 

 tains, which bound the valley of Hagerstown towards the west. The 

 underlying rock of this valley may be taken as a type of the whole 

 transition lime formation of this region. It is generally a dark blue 

 rock, of very uniform texture and appearance, occasionally traversed 

 with veins of calcareous spar, and almost entirely destitute of organic 

 remains. The sparry variety is best seen in the vicinity of Frederick 

 city, and there is hardly a quarry to be found in any direction within a 

 few miles of that place, where these veins are not abundant. It is 

 this variety that has been distinguished by the name of sparry lime- 

 rock. A few miles east of Hagerstown, the exact spot I am not ac- 

 quainted with, this stratum includes a bed of white and perfectly fine- 

 grained limestone, which is quarried for white marble, and answers 

 well for that purpose. The only organic remains, that I have ever 

 known found in this rock, are some beautiful specimens of pentacri- 



