468 STRATIGRAPHICAL GEOLOGY. 



to that in Bethlehem, and it has been often described. South, where it 

 occurs in Grantham and Unity, and in the more extended area in Ches- 

 hire county, it is generally finer-grained. The feldspar is often reddish, 

 and it sometimes contains hornblende ; the chlorite is in places abundant, 

 but elsewhere there is little, or it is wanting altogether. In general, how- 

 ever, its lithological characters are such that the rock is easily recognized. 



3. Coinmon or Lake Gneiss. In the north part of the area it has uni- 

 formly a remarkably coarse texture, and is composed largely of quartz 

 and black mica, and generally the mica is quite abundant. 



4. Ferruginotis Concretionajy Schist. This is largely developed in the 

 south-east part of Cheshire county. It is a siliceous schist, nearly every- 

 where pyritiferous, and frequently contains brilliant garnets in imperfect 

 crystals. It is sometimes plumbaginous, and, as in Nelson, it contains 

 extensive beds of plumbago or graphite. 



5. Fibrolite Schist, sometimes gneissic and passing into common mica 

 schist. It is often thick-bedded, and is characterized by having immense 

 veins of coarse granite along its entire outcrop. 



6. Quartzites and Quartz Conglomerates. These are evidently of the 

 same age as those of the Connecticut Valley district. 



7. Intrusive Rocks and Veinstones. 



Laurentian Series. 



Porphyritic Gneiss. The lithological characters of this rock have been 

 so often described in preceding pages, that it is not necessary to repeat 

 the description here. It is characteristically developed in Ellsworth, to 

 the north-west of Stinson pond; in Rumney, at the north end of Stinson 

 mountain ; on Mt. Cardigan ; also, in Sunapee, Stoddard, Marlow, Chester- 

 field, Winchester, Hinsdale, and Rindge. In Canaan there are crystals 

 of feldspar ; but the general character of the rock is that of the common 

 gneiss. The area north-west of Stinson pond is in the forest; and on 

 both sides of it we have fibrolite schist. In Ellsworth it outcrops on 

 Moulton brook, where the road crosses it at H. & D. Sanborn's mill. 

 The strata appear to be vertical. Here, also, we have mica schists and 

 a fibrolite on the west. Both outcrops, however, are some distance from 

 the mill. Going east, the next outcrop of porphyritic gneiss is near G. 

 Avery's, in the road, probably sixty rods west of the house. Here it 



