REPORT. 



A GEOLOGICAL RECONNAISSANCE IN THE CRYSTAL- 

 LINE ROCK REGION, DUTCHESS, PUTNAM AND WEST- 

 CHESTER COUNTIES, NEW YORK. 



The country covered by the reconnaissance described in this report 

 occupies the eastern and south-eastern portions of Dutchess county, the 

 whole of Putnam county and the northern and middle parts of West- 

 chester county. The territory is very naturally divided into the fol- 

 lowing four parts or belts : 



1. Stissing Mountain. 



2. East or Dover Mountain. 



3. Highlands east of the Hudson River, 



4. Westchester County. 



The report consists of general and detailed descriptions of the limits 

 of the Archaean rocks in the first, second and third of these divisions; 

 secondly, of notes on the geological structure, so far as the data col- 

 lected lead us to infer it; and, thirdly, descriptions of the character- 

 istic rocks of the several belts. Following these descriptions are refer- 

 ences to published articles on the geology of each belt; and, lastly, a 

 brief statement about the geological age of these crystalline rocks. 



The analysis shows: 



I. Stissing mountain. 



1. Geograpliical location and lieiglit. 



2. Geological boundaries. 



3. Structure. 



4. Descriptions of rocks. 



II. East or Dover mountain. 



1. Geographical situation and lieiglit. 



2. Outlines of gneissic rocks. 



3. Structure. 



4. Rocks. 



III. Highlands of the Hudson. 



1. Geography and topography [notes]. 



2. Limits of the Arch;¥an rocks. 



3. Notes on geological structure. 



4. Structure. < 



5. Notes on typical rocks. 



6. References to literature on Highlands. 



7. Geological horizon — Archaean. 



IV. Westchester county. 



