506 RECORDS 



SECTION OF GEOLOGY AND MINERALOGY. 



November 19, 1900. 



Section met at 8:15 P. M., Dr. A. A. Julien presiding. 



The following program was offered': 



J. F. Kemp, Recent Progress in Investigation of the 

 Geology of the Adirondack Region. Illustrated with speci- 

 mens and diagrams. 



A. A. Julien, Notes on the Origin of the Pegmatites 

 FROM Manhattan Island and from North Carolina. Illus- 

 trated with specimens and diagrams. 



Summary of Papers. 



Professor Kemp outlined the area of crystalline rocks in the 

 northern part of New York State and illustrated its distribution 

 by means of maps. Three principal classes of rocks are present. 

 First, those certainly igneous in their nature, including the lab- 

 radorite rocks, the basic gabbros and the trap dikes. Second, 

 those certainly sedimentary, best illustrated by the cr>^stalline 

 limestones. Third, great areas of gneiss of uncertain origin. 

 Regarding the first class, we now know quite accurately their 

 distribution and the results obtained by the speaker, by H. P. 

 Gushing and C. H. Smyth were briefly reviewed. A short de- 

 scription was given of the augite-syenite first discovered by Gush- 

 ing near Loon Lake, but which has since been found to be 

 widely distributed in the regions further south. Some notes 

 were also given regarding the ages of the trap dikes and their 

 distribution. 



Recent additions to the knowledge of the sedimentary rocks, 

 involve the recognition of quite large amounts of quartzites in a 

 considerable number of new localities. Besides these, small 

 beds of limestone have been discovered in the southern areas, 

 especially in Warren and Washington counties, which are thor- 

 oughly interstratified with the gneisses and which leave no escape 

 from concluding that the gneisses are also sedimentary in their 

 origin and that a regularly stratified series of rocks is present. 



