132 NEW YORK STATE MUSEUM 



of temperature of 1° C. for each 100 feet of descent, we call for 

 II miles of depth to reach 575° C. This is beyond the belief of 

 a conservative mind and forces us to the assumption of some local- 

 ized source of heat, i. e. intrusive rocks. We may think of the 

 ore as being more or less akin to pegmatites in its formation, and 

 of the walls as perhaps being formed somehow under the influence 

 of mineralizers so as to require less exalted temperature of crys- 

 tallization than normal eruptives, but igneous phenomena and 

 influences in some form we can not reasonably escape. 



Unsatisfactory as the available suggestions of origin may appear, 

 it should always be realized that we are dealing with very obscure 

 and difficult questions at best, and with rocks of great age an I of 

 complicated history. To whatever portion of the world we turn 

 for the results of similar studies, we find geologists involved in the 

 same difficulties. The best that one can do is to present a candid 

 statement of the case leaving for the future such further light as 

 the general advance of the science may afford. 



Nichols Pond magnetite. From 3 to 3^ miles north of the 

 Fisher hill and Hall mines, there was formerly active a small enter- 

 prise based upon an exposure of magnetite on Campbell mountain 



Fig, 29 lean magnetite, Nichols Pond pit. The white isquartz; the black magnetite. 

 The aggregate resembles a quartz vein with magnetite. Actual field I'o of an inch. 



a mile west of Nichols pond. The principal open cut is practically 

 on the summit of the mountain so that from it one looks away to 

 the north across the valley of the Black river. According to J. C. 

 Smock [N. Y. State Mus. Bui. 7, 1889, p. 36J operations were- 

 begun in 1845 and continued to 1850. The openings are on lots 

 166 and 168 of the Iron Ore tract. Either at this time or later a 

 concentrating mill was erected upon the shores of Nichols pond 



