Preliminary Report on the Geology of Essex County. 



By J. F. Kemp. 



(Continued from the Report of the State Geologist for the Year 1H93, pp. 433-472.) 



The field work for the accompanying report was done in September, 

 1894, and September, 1895. In the former month a trip was made from Port 

 Henry across North Hudson and Newcomb townships and into the old iron 

 mining settlement at lake Sandford at the expense of the Geological Depart- 

 ment of Columbia University. In September, 1895, the field expenses were 

 borne by the State. Almost indispensable aid has been afforded by the 

 topographic maps of the United States Geological Survey, so far as prepared 

 or available, but the western townships have not yet been mapped in this 

 way, or at least have been drawn only along their eastern borders, and the 

 lack of an accurate location of water courses and boundaries has been felt in 

 these districts. Acknowledgments are due to Mr. Herbert M. Wilson, of that 

 Survey, for his courteous and prompt supply of advance sheets. 



The same series of signs and the same provisional nomenclature that was 

 used in my former report has been continued in this one, and to those intro- 

 ductory pages, 444-451, reference may be made for their full elucidation. 

 For the sake of clearness, however, a brief outline of the several divisions 

 is here repeated. The additional observations have corroborated these previ- 

 ously published generalities, but it is doubtful if a sharp stratigraphic 

 distinction can be drawn between Series I and II. It seems increasingly 

 probable that the crystalline limestones may prove to be but phases, perhaps 

 several times repeated of Series I, but they are lithologically distinct and 

 peculiar. They are noticeably more abundant to the south and southwest. 

 In this connection results to be obtained in mapping Warren county are to 

 be awaited with interest. 



Series I. Gneisses usually with both orthoclase and quartz. Varieties 

 with hornblende, biotite, pyroxene, and with almost no dark silicate, are met. 

 Plagioclase is usually present and may be the only feldspar. The exposures 

 vary in color from very light grey, almost white, to dark grey or even to red. 

 The lamination may be conspicuous or may almost fail. 



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