Feather stonhaugVs Geological Report. 101 



of the limestone, which may be considered the equivalent of 

 the lowest beds of Mr. Murchison's Silurian rocks. 



These non-fossiliferous beds extend now a long way up the 

 river, which is very tortuous, embracing many beds of hydrau- 

 lic lime, which, as well as the common limestone, when pure, 

 has added much to the value of real estate here since the con- 

 struction of the canal. The compact dark blue kind makes 

 an excellent mineral manure, but cracks when used as plas- 

 tering for rooms, an objection the whiter kinds are not so 

 obnoxious to, they being less ferruginous. The whole dis- 

 tance up the river, the beds are anticlinally arranged, often 

 forming complete arches, and occasionally the seams, not more 

 than eight inches wides, are disposed into concentric forms of 

 forty feet diameter. At Shepherdstown a band of quartzose 

 red sandstone, about three feet broad, sometimes crossed with 

 small seams of carbonate of lime, runs through the strata of 

 limestone due north and south. I obtained a singular speci- 

 men from it, with septae standing on its face in relief, like chain 

 coral. Higher up lofty bluffs of limestone approach the river 

 on boih sides ; some of them on the left bank are cavernous, 

 with pendent stalactites inside. Near Williamsport the beds 

 frequently dipped both ways in a short distance ; indeed, in 

 some localities they have a wavy structure, forming a set of 

 anticlinal and synclinal lines, as in diagram 10, where, at a, a 

 ravine, the continuity is interrupted by the removal of mine- 

 ral matter. Diagram No. 11 represents another locality near 

 Williamsport, where, at a, a part of the beds seems to have slid 

 off, and to have left a ravine, where trees are now growing. 

 The main beds of limestone here are about three feet wide. 

 In approaching the Alleghany ridges the evidences are abun- 

 dant of a great disturbance in the beds. I copied the appear- 

 ances exhibited by them in diagram 12, within the space of 

 three miles. At Williamsport a slaty shale comes in at the 

 river, through which a road has been cut to the canal bridge, 

 which exhibits the laminae standing in every possible direc- 



