APPENDIX A. 163 



sect obliquely the strike of the strata, which is over all this space in 

 the general northwest and southeast direction, with a southern dip, 

 without a change of the direction which would cause a repetition. 

 The thickness of the slate deposits must, consequently, be enor- 

 mously great. In Section 30, after crossing two creeks running 

 parallel with the strike of the strata, we came upon a belt of trap 

 rock protruding as an abrupt hill range above the surrounding 

 slate. This possibly may be the direct continuation of the trap 

 range we found the day before, in Sect. 19, or, perhaps, a distinct 

 belt, of which there seem to be many intercalated with the slate 

 formation. 



In Section 28 we enter the valley of another creek, along which 

 the slate quarries are located. No change in the strike and dip of 

 the strata is observed. The useful slate rock is a seam of the im- 

 mense series already transgressed, differing from the rest only in 

 possessing a more regularly laminated character. It is susceptible 

 of being split into large, even slabs of any desired thickness, with 

 a fine, silky, homogeneous grain, and combines durability and 

 toughness with smoothness. Its color is an agreeable black, and 

 very uniform. Several companies have located their quarries along 

 the creek which runs parallel with the strike of the strata, and a 

 tram-road about 3|- miles in length has been built down to the bay, 

 where a dock is erected for the unloading of vessels and for con- 

 venient shipment of the slate. 



I followed the exposures of the slate rock, which, however, are 

 not all of the better quality, along the section lines of 28, 27, 26, and 

 25. Not far from there, in the next township, Range 30, Mr. Hurley 

 has commenced to work a quarry, which so far furnishes a product 

 fully equal in quality to that of the other quarries. On the town 

 line between Sees. 24 and 25, I found another belt of trap protrud- 

 ing as an abrupt hill above the surrounding country. Its strike is 

 nearly east and west, its dip south, and on both sides are slates of 

 conformable strike and dip. The trap belt is about 60 feet wide, a 

 dark hornblende rock, with quartz and chlorite veins, and divided 

 into rhomboidal blocks by cleavage cracks, altogether resembling 

 rather an intrusive mass than a sedimentary layer. 



Along the tram-road, toward the bay, after intersecting a series 

 of roofing slates, a dark belt of trap rock of about 100 feet thick- 

 ness is crossed. Following this is a belt of white quartzite about 



