NEW YORK STATE MUSEUM 



siderable scientific interest. As very accurate, large scale topo- 

 graphic maps were available, the boundaries of the various form- 

 ations were determined rather more closely than had heretofore 

 been possible. Recent cuttings for streets in the northern part 

 of the island showed that the crystalline (Inwood) limestone is 

 injected in many places with coarse grained rocks (aplites or 

 pegmatites), usually approaching the granites in mineral composi- 

 tion. One well marked and somewhat extensive type, however, 

 consists essentially of albite and quartz. Specimens were taken 

 from all the outcrops visited. Records of borings made for wells, 

 foundations, bridges and docks were collected. 



At the close of this work on New York island, Mr Eckel was 

 instructed to commence work in Westchester county. From 

 April 20 to September 20 he was employed in a final review of 

 that part of Westchester county lying south of the line Dobbs 

 Ferry- Whiteplains-Larchniont. Critical outcrops were exam- 

 ined and specimens taken, while the boundaries of the various 

 rock areas were carefully traced, preparatory to the publication 

 of the final map of the region both in the New York geologic folio 

 of the United States geological survey 1 and in the report of the 

 state geologist. This final field work on the Harlem sheet, ad- 

 visable in view of the great importance of the area mapped, both 

 in geology and commerce, proved incidentally the great accuracy 

 of the " Geologic map of a part of southeastern New York " pub- 

 lished in 1895. With the exception of one small belt of Inwood 

 limestone, uncovered by recent excavations, no features of areal 

 importance were developed additional to those shown on that 

 map. Particular attention was paid to the condition of the 

 quarry industry throughout the region covered, specially in the 

 areas of Inwood limestone and Yonkers gneiss. Statistics regard- 

 ing both building stone and road materials were gathered and 

 full sets of specimens collected. 



Late in September the small area of crystalline rocks exposed 

 on the western end of Long Island was examined and mapped 



iThe geology of the Harlem sheet will be issued from the office of the 

 U. S. geological survey at Washington in the autumn of 1901 and a dupli- 

 cate edition will be issued at the same time by the New York state printer. 



