•^ _ _ ■ jjr. 



NEW IIAMPSIIIKE. 



387 



" 2. Bethlehem Gneiss. 



" It is usually granitic, so much so that it has always been called granite 



heretofore Lying between outcrops of porphyritic gneiss the natural 



inference is that it is a synclical, and therefore newer, while the strike indi- 

 cates a very great an ti(]^uity judging from the same phenomenon elsewhere. 

 .... If the anticlinal structure is persistent, evidence may be afforded that 

 this peculiar gneiss is older than No. 1." 



*' 3. Gneiss. 



*' 4. White Mountain or Andalusitc Gneiss. 



*' It seems to be newer than Nos. 1 and 2, but the relations to the granites 

 and norian are yet to be made out. 



*' 5. Common Granite. 



*'The joints passing through this rock are both horizontal and vertical. 

 .... East of Saco the Andalusite gneiss seems to have been cut by it." 



*' 6. Trachytic Granite. 



*' Above No. 5, with the same horizontal appearance." 



** 7. Brecciated Granite. 



'* The rock is irregular in arrangement as if thrust up from below. As it 

 contains no fragment of the common and trachytic granite, we have concluded 

 it to be more ancient than either of these granites, but newer than the porphy- 

 ritic gneiss. The two areas are also probably connected beneath the Pemige- 

 wasset valley under the common coarse granite, which either flowed in above 

 the breccia or was deposited upon it quietly in some other way." 



*'8. Norian. 



** This includes several areas of labradorite rock, including compact felsites, 

 breccias and syenites." 



" 9. Clay, Slate and Quartzites. 

 ** 10. Coos Group." 



Couceruing the ago of the Norian and some others of the precccding 

 divisiouB, Prof. Hitchcock remarks : 



" AH wdll agree that the mineral labradorite belongs to the original lauren- 

 tian system, and therefore by its discovery in New Hampshire will be satisfied 

 that some of our crystalline rocks belong to the older series of the Eozoic, and 

 not the Paleozoic. Hence the prevalent opinion respecting the age of the New 

 England metamorphic rocks must be changed to conform with the discovery of 

 labradorite in our state Our conclusions as to the absolute and relative 



ages of the New Hampshire formations depend upon the reference of some of 

 them to the Norian system of Hunt." (I c, pp. 4-10.) 



Dr. Geo. W. Hawes regai'ded the Noritc rock as eruptive, saying : 



" At some points the rock possesses all the structure of an eruptive mass, 

 and when in other places this is not found, the evidence furnished by more 



