REPORT OF THE DIRECTOR AND STATE GEOLOGIST rO 



accurately. The outcrops show that most of this area consists 

 of a highly foliated quartz diorite, intrusive in the Fordham 

 gneiss, the latter formation being exposed at a few points only. 



The revision of the geology of Putnam county has been out- 

 lined by a reconnaissance made during August, September and 

 October by Benjamin F. Hill, fellow of Columbia university, fol- 

 lowing on the brief study of the valley of the Hudson in Putnam 

 and Orange counties made during the previous summer by D. H. 

 Kewland. This work, while technical in character, and chiefly 

 a contribution to our knowledge of the crystalline rocks, is of 

 much general interest in that it is a prerequisite to the publica- 

 tion of the new geologic map of the state of New York. 



Adirondack geology 



Work in the great field of study of the pre-Cambrian rocks of the 

 Adirondack area has been continued by three geologists, all well 

 known as authorities in this branch: Prof. J. F. Kemp, of Col- 

 umbia university, Prof. H. P. Cushing, of Adelbert college, Clevfr 

 land (O.), and Prof. C. H. Smyth jr, of Hamilton college. 



The field work in charge of Prof. J. F. Kemp was chiefly done 

 by his assistant, Benjamin F. Hill, during June and July. The 

 main object was to cover points not reached in previous summers. 

 Mr Hill proceeded first to Sprakers in the Mohawk valley and 

 studied the outlier of crystalline rock brought up by a fault from 

 beneath the Paleozoic at that point. He then moved to Glovers- 

 ville and explored the country adjacent to it. From Gloversville 

 he changed his base to Caldwell and mapped the crystalline rocks 

 at the southern end of Lake George, and, going thence to Xorth 

 creek, gave special attention to the geology of the garnet de- 

 posits and traversed the country just west of Thirteenth lake. 



Prof. Cushing's field work commenced at Tupper lake. Franklin 

 county, proceeding north from there along the New York and 

 Ottawa railroad, following the boundary between the anorthosite 

 and the adjoining rocks on the west, which consist largely of 

 syenites, in the endeavor to determine the time relations between 

 the two. A locality was found near Tupper lake where a rock, 



