26 PHYSICAL GEOGRAPHY. 



mine; other mining properties, particularly beds of pyrites in Croydon, 

 Unity, Lebanon, etc. ; G. A. Wheelock's researches about Keene ; various 

 brief excursions ; and the map of Dalton. 



It was stated in the first report that very material aid might be fur- 

 nished us in our explorations if the proprietors of large tracts of land 

 would aid us in tracing out the formations upon lands in which they feel 

 an interest. This appeal was immediately answered by J. B. Sumner, 

 Esq., of Dalton, who furnished the means for a careful survey of the 

 township of Dalton. The work was performed by Mr. Huntington, who 

 prepared a map of the township, on the scale of one hundred and six rods 

 to the inch, showing the several formations, as well as the courses of the 

 metallic veins and the location of mineral deposits. A copy of this was 

 sent to Mr. Sumner, with an explanation of the significance of the 

 several colors. The facts ascertained are all embodied in our general 

 geological map. 



The New Map of the Second Year. 



The map of the state spoken of above showed several geological fea- 

 tures, under the following headings: i. White Mountain, or gneissic 

 series. 2. Sienite group of Exeter and Dover. 3. Porphyritic gran- 

 ite. 4. Common granite. 5. Merrimack group. 6. Quebec group. 

 7. Coos group. 8. Calciferous mica schist. 9. Clay slates. The re- 

 marks made about them are here reproduced, in substance: 



I. White Mountain or Gneissic Series. In our report of last year this term was used 

 to indicate the general mass of gneissic and granitic rocks of the state, including desig- 

 nations three and four of the present map. It occupies four fifths of the area of the 

 state ; and it will be a leading object of our survey to discover the relations of the sev- 

 eral members of the group to one another. It may not be amiss to state that the clue 

 to the structure of the whole has probably been discovered, and that, by diligence and 

 discrimination, it can be completely followed out. The practical advantages of this 

 knowledge can hardly be overrated, since information will at once be afforded restrict- 

 ing the occurrence of valuable minerals to narrow areas, where the proper research will 

 develop them. I refer to such minerals as the soapstone of Francestown, the pyrites 

 of Sullivan county, the mica of Grafton, granites, limestone, feldspar, tin, lead, etc. 



I am satisfied that the following are some of the subdivisions of this group, which 

 further explorations will enable us to define with precision : 1, normal gneiss ; 2, fer- 

 ruginous gneiss; 3, granitic gneiss; 4, feldspathic mica schist; 5, andalusite gneiss; 



