REPORT OP THE DIRECTOR AND STATE GEOLOGIST 195 



THE NORTHEAST EXTREMITY OF THE PRE CAMBRIAN 



HIGHLANDS 



BY F. J. H. MEREILL 



With map by T. Nelson Dale 



The northeast extremity of the Precamibrian highlands of Put- 

 nam and Dutchess counties lies in an area of great geologic 

 interest. This is due to the fact that the exposures there afford 

 opportunity for the correlation and comparison of the crystalline 

 formations of southeastern Dutchess county, with those of 

 southern Putnam and Westchester. Reconnaissance surveys of 

 this region were made during the period between 1896 and 1902 

 by F. J. H. Merrill and his assistants Benjamin F. Hill and 

 Edwin C. Eckel. In Au,gust 1903, being in Pittsfleld, the State 

 Geologist had an opportunity of seeing a field map of a part of 

 the district made in 1892 under the direction of Professor Raphael 

 Pumpelly, by T. Nelson Diale and L. M. Prindle, field assistant. 

 This map was on the scale of 2 miles to the inch and was so com- 

 plete in minute detail, that it attracted the attention of the writer 

 and Professor Dale kindly offered him the use of it for publica- 

 tion, subject to the approval of Director Walcott. The permis- 

 sion of the latter was most cordially given and the map appears 

 in illustration of this paper. Professor Dale's notes are records 

 of the outcrops and express no conclusions concerning the forma- 

 tions, the discussion on which is based on the writer's own studies 

 in the district. 



The area in question falls on the Glove topographic quadrangle, 

 a portion of which is colored geologically to illustrate this paper. 

 The rocks of the region are a Precambrian formation of gneiss ; 

 a basal Paleozoic quartzite of Lower Gambrian age; a Gambro- 

 Silurian limestone, stratigraphically equivalent to the Stock- 

 bridge ; and a highly metamorphosed crystalline schist, of Hudson 

 age, equivalent to the Berkshire schist of the New England 

 geologists. 



Near Poughquag village is a most extensive exposure of the 

 basal Gambrian formation which from this locality has received 



