GEOLOGY OF THE PARADOX LAKE QUADRANGLE 505 



intrusive along planes of weakness, and can only be explained as an 

 injection of carbonaceous and ferruginous materials in a fluid or 

 gaseous condition. A reducing action of iron compounds on 

 hydrocarbons might result in the formation of the graphite and 

 pyrite which we constantly find associated. 



But the widespread dissemination of graphite scales in sedimen- 

 tary limestone and quartzite can best be explained on the organic 

 hypothesis. There seems no possibility of any origin but that of a 

 metamorphic product from some original constituent of the rock, 

 and regional metamorphism is the only process by which it can 

 reasonably be supposed to have been formed. It seems most prob- 

 able that the original limestone and sandstone were heavily charged 

 with organic material which in the Prepotsdam period of meta- 

 morphism was completely reduced and in some part volatilized. 

 The organic material thus reduced remains in its original position 

 as graphite, while the volatilized portions spread along every avail- 

 able plane of weakness and form the deposits of economic 

 importance. 



Titaniferous magnetite. Titaniferous iron ores appear on Moose 

 mountain. The occurrence of these ore bodies is evidently to be 

 explained in the same way as the aggregation of minerals in the 

 anorthosites. The titaniferous ores always occur in the anorthosite, 

 or gabbro, and represent the extreme development in the direction 

 of producing an aggregation of iron minerals. The process is 

 entirely analogous to that of the production of anorthosite from 

 gabbro by increase in feldspar, or of pyroxenite from gabbro by the 

 decrease in augite. There is no evidence of intrusion, nor of vein 

 formation in the occurrence of these ores, nor have they any relation 

 to faults or crushed zones. The titaniferous iron ores of the 

 Adirondacks have been fully treated by Professor Kemp. 1 



Nontitaniferous magnetites. Reference has already been made in 

 Professor Kemp's preliminary report 2 to the magnetite deposits of 

 Hammondville and to the Schofield ore body. Both deposits occur 

 in the granite of a type containing almost no ferro-magnesian 



1 U. S. G. S. 19th An. Rept pt 3. Economic Geology, p. 379-422. 

 ^Geology of Essex County. N. Y. State Geologist An. Rept for 1893 

 and 1895. 



