Feather stonhaugh s Geological Report. 99 



exceedingly contorted at times, but with a general dip to the 

 east, break through the common level. At Harper s Ferry, 

 twelve miles further, these slates, which rise to a very lofty 

 mural escarpment of eight or nine hundred feet, dip almost in 

 every direction ; sometimes the seams appear to form round 

 nodules of one hundred feet in diameter, often are vertical, then 

 again become concentric. The whole mass is in a state of great 

 confusion, which is increased by the cleavage, here exceedingly 

 deceptive. One mile, however, further west, the laminae of 

 the slate become thin and numerous, and show the true dip, 

 which is easterly. This is confirmed by the edges of the beds 

 in the Shenandoah at low water. A few miles beyond this 

 point, the character of the country again changes, the slates 

 disappear, and we come upon vertical laminae of limestone, 

 which, somewhat further on, dip to the west. 



Reverting to the breccia, and with a view to give a more 

 satisfactory explanation of it, I shall now trace another sec 

 tional line, parallel to the one which has been described, but 

 reversing the direction, and descending the country from 

 northwest to southeast. By following the edge of the lime 

 stone spoken of as lying in vertical laminae, the traveller comes 

 upon Boonsborough, in Maryland, a town which stands upon 

 the western flank of the Blue ridge, where it joins the great 

 formation of transition limestone, as it has hitherto been called. 

 On this line he finds the Blue ridge composed of primary 

 slates, chlorites, and sandstones, with conglomerate grits, to 

 the eastern foot of the ridge, all dipping east. Entering the 

 Middletown valley, he finds a decomposed red shale and tal- 

 cose slate. Leaving Middletown, which is eight miles from 

 Boonsborough, he crosses the Cotoctin mountains, composed 

 of chlorite rocks and slates, with green epidote and whitish 

 slaty sandstones, and advances towards Fredericktown, also 

 distant. eight miles. When he has left the mountains behind 

 him, and has advanced to within two and a half miles of the 

 city, he finds the ground covered, for a breadth of several hun- 



