REPORT ON GEOLOGY. 



Prof. Jame3 Hall, Director of the State Museum of Natural History 



and State Geologist of New York : 



SlE — In conformity with your letter of instructions to me, of date 

 August 4, 1885, respecting the field work of the year, I began work in 

 Dutchess county August 19th. It was continued with some interrup- 

 tions (amounting in the aggregate to one month) to December 5, 

 1885. 



The first part of my survey was a hurried reconnaissance across 

 Westchester and in the eastern part of Dutchess county; and a section 

 across the Mount Washington range, Massachusetts and eastward into 

 northern Connecticut as far as Norfolk in that State. 



The work of tracing the outlines of what were recognized as 

 Archfean rocks was then taken up and the geological boundaries of the 

 Stissing mountain range; of the East or Dover mountain range; and 

 then, of the Highlands east of the Hudson were followed and located. 



The relations of the bordering or over-lapping formations of Potsdam 

 sandstone, of blue, magnesian limestone, of Hudson river slate, and of 

 the mica schists and quartzytes on the east and south-east of the High- 

 lands were ascertained, as far as could be done from their respective 

 outcrops. 



A few sections across the Archsean outcrop were traversed and the 

 position of the strata noted. 



Collections of the crystalline rocks and from the newer adjacent, sed- 

 imentary strata were made incidentally while at work on the geological 

 map. About 500 specimens (many very small, however, and not cab- 

 inet specimens) were collected from 380 localities. 



The general results of this reconnaissance are presented in the fol- 

 lowing report. 



JOHN C. SMOCK. 



Xew York State Museum, Albany, N. Y., Jan. 13, 1886, 



