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NEW YORK STATE MUSEUM 



Although by far the largest quantity of pink granite gneiss is 

 found in broad continuous areas in the uplands adjoining Canton, 

 Eddy and Pyrites villages, a very considerable amount is inter- 

 banded with the amphibolite and garnet gneiss zones of the Pierre- 

 pont sigmoid. The intrusive here has formed a second injection of 

 the leaf or " lit-par-ht " type with each of the two preexisting 

 country rock formations, which, as already noted (pages 57-59), 

 were themselves similarly related by the earlier invasion of the basic 

 rock into the garnet gneiss. This double injection, first of gabbro- 

 diorite into Grenville siliceous garnetiferous gneiss, and, second, of 

 granite into each of these, has resulted in an unusually interesting 

 association of these. three strongly contrasted formations, and to an 

 abrupt alternation of the red, black and spotted garnet bands which, 

 till their mutual relations are understood, is not a little puzzling. 



The granitic injection is of a finer texture, generally speaking, 

 than the gabbroic. In other words, the admixture of the acid ma- 

 terial with the amphibolite and garnet gneiss is, on the whole, more 

 intimate and thorough than is the case with the earlier injection. 

 The granite lenticles, or units of injection, assume much smaller di- 

 mensions, and a more rapid alternation with their country rock, than 

 is to be observed between the amphibolite and garnet gneiss. Thus, 

 while the bands of amphibolite are bulky and do not minutely sub- 

 divide the garnet country rock, the granite, on the other hand, has 

 frequently penetrated both of these formations with microscopic 

 fineness. For example, on the 820 foot knoll, west side of a brook, 

 and about three-tenths of a mile west of the fork in the road i mile 

 southwest of Pierrepont, the injection of the granite into a mass of 

 amphibolite (which may have been of xenolithic character) is so 

 intimate as to have effected a veritable disintegration or dissolution 

 of the schist with the production of a true mixed rock. Plate 11, 

 lower figure, though unfortunately a poor photograph, shows small 

 nodular remnants of black schist in the midst of a reddish black, 

 soaked rock of this character. This extreme phenomenon, however, 

 is not common, but a moderate admixture is the one usually met 

 with, the component parts of which are of about the same order of 

 magnitude as in the amphibolite-garnet gneiss injection zone. 



It is not to be supposed, however, that the granite intrusive has 

 injected the country rock uniformly throughout the sigmoid area. 

 Inhere are considerable areas, especially east of Beach Plains Church, 

 where garnet gneiss is relatively free from such material ; and in this 



