52 



STRATIGRAPIIICAL GEOLOGY. 



South-west of Millsfield ponds, within the limits of Millsfield, the rocks 

 ^ consist chiefly of very dark sihccous slates, while 

 c south-west of Newell brook it is followed by gray 

 n gneisses of the Montalban group. East of the An- 

 ° droscoggin, on the line of Errol and Cambridge, we 

 I have the light gray siliceous schist characteristic of 

 !^ the Huronian. In the central part of Dummer, im- 

 ^ mediately east of the Androscoggin, there is an out- 

 's crop of chlorite and siliceous schist ; but west of the 

 < river, especially in the valley of the stream that flows 

 Z from Dummer jDonds, there are no outcrops of rock, 

 "g but a mile south-west of the Dummer ponds there 

 ^ are many extensive outcrops of gray siliceous schist. 

 S At West Milan it is interstratified with hornblende 

 ; schist. It outcrops a mile and a half south-east of 



o 



•^ West Milan, and its extension west to Stark water- 



I g- station gives to the rock here a great width, but its 

 ^ ^ nearly vertical state suggests that it is made up of 



I I numerous folds, as we can trace both synclinal and 

 ■g s anticlinal axes. The western group of Huronian 

 _■ rocks begins near the north line of Stratford, where 

 I they consist of dark siliceous schists. Extensive out- 

 -^ crops are found at the head of Bog brook, along the 

 ^ west side of Percy peaks, on the south of Potter's 

 I pond in Stark, the east side of the Devil's slide and 

 ", Mill mountain, on the east side of the hill south-east 

 S of Groveton, and between Mt. Lyon and the Pilot 

 I range. On the Connecticut, in the south part of 

 = Stratford, is the light gray siliceous schist, and this 

 ^ extends eastward and outcrops on Nash stream. 

 I From near the north line of Northumberland, and 

 ^ southward through Lancaster and terminating in the 

 I north part of Dalton, the rock consists of feldspathic 

 ■£ chloritic schists. These frequently have hornblende 



c 



^ and epidote as accessory minerals. In Dalton the 



