100 



Feather stonhaugli^s Geological Report. 



dred yards, with immense dislocated masses of the calcareous 

 br-eccia, some of them weighing fifty tons, and the fragments 

 and pebbles of which it is composed cemented together with 

 a red argillaceous earth. One mile from Frederick he finds 

 the limestone as regularly in place as it is west of the Blue 

 ridge, its edges crossing the road in a direction of northnorth- 

 east to southsouthwest, sometimes dipping easterly, and fre- 

 quently vertical. The limestone continues uninterruptedly 

 to the Monocacy river^ on the eastern side of which laminated 

 slates and shales commence. We have thus all the proofs 

 that the Atlantic primary chain has come up from below 

 through the limestone, triturating and breaking it up into frag- 

 ments of every size, which were subsequently transported to 

 the east side of the chain by a current from the west, and de- 

 posited there, intermixed with the decomposed red shale, for 

 no conglomerate has yet been found on the western side. 

 This great elevatory movement seems to have been followed 

 by another, which has given the anticlinal arrangement to all 

 the rocks of the country ; for, after the first deposition of the 

 breccia, we find it dislocated and broken up into the masses 

 before spoken of. This must have taken place posterior to its 

 semi-induration, for, where it lies undisturbed^ the fragments 

 of which it is composed are, in numerous localities, rent in 

 every direction, their corresponding parts often shifted, and 

 the fissures filled up with the carbonate of lime. This curious 

 state of the breccia is well exhibited in the columns of the 

 Senate and House of Representatives at the Capitol. I have 

 followed this breccia for great distances along the eastern flank 

 of this chain, and have found it always similarly situated ; only 

 in some localities, as in Fauquier county, Virginia, to the 

 northwest of the town of Buckland, the breccia is not com- 

 posed of limestone, but of slates, sandstones, and quartz, 

 because the limestone has never extended to that parallel. 

 We may safely infer, from all these circumstances, that the At- 

 lantic primary chain was elevated posterior to the deposition 



O i) -l 



