STRATIGRAPHICAL GEOLOGY. 



Lime, 

 Soda, 

 Potash, 



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On the hill east of Groveton the character of the rock is nearly the 

 same as that of Mt. Lyon. On the north side, however, the debris has 

 fallen down so that no outcrop appears until we get nearly to the top. 

 On the east side of this hill there is a schist, which is almost a quartzite, 

 that comes immediately in contact with the por- 

 phyrite. Between Mt. Lyon and the porphyrite 

 east, there is a band of schistose rocks, which 

 perhaps may be properly called an argillaceous 

 quartzite. This band forms a synclinal axis be- 

 tween the porphyrites. The view of Mt. Lyon, 

 from which the heliotype was made, was taken 

 at a point near Groveton, and its pointed summit 

 shows a characteristic of our porphyrite moun- 

 tains. East of the road from Groveton to Lost 

 Nation, and three fourths of a mile from it, the 

 porphyrite outcrops, and from thence to the head 

 waters of the Upper Ammonoosuc it appears to 

 be continuous. The porphyrite of this region 

 seems to be spread out in nearly horizontal lay- 

 u i^ ers. The lower portion is a dark, compact rock, 

 |f with few distinct crystals of feldspar, and it al- 

 5 I ways weathers whitish. The upper portion, which 

 "; .;, caps the summits of nearly all the higher peaks, 

 \l is a light-colored porphyrite, and the crystals of 

 \ I feldspar are always distinct. The only one of 

 £ rt the higher mountains that is not thus capped is 

 ^ I the one that is known as South peak, a sharp, 

 conical mountain, that can be seen looking south from Stark station. 

 While the succession of rocks is so nearly the same, in so many dif- 

 ferent localities, it has been taken as presumptive evidence that these 

 rocks arc stratified ; but as there are so many places where the porphy- 

 rite penetrates the rocks with which it comes in contact, the intrusive 

 character of this rock cannot be doubted. The same reasoning in regard 



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