18 



Report of the State Geologist. 



Malone. 



In this township the boundary pursues a west-south-west course 

 nearly to the western line of the town, when it bears away to the north along 

 the edge of Cornish hill, a massive ridge of gneiss which extends well up into 

 Bangor. As in Belmont, low ridges and spurs of gneiss protrude through the 

 drift along the boundary, separated from one another by shallow, drift-filled 

 depressions. 



The gneisses are of the same general character as in Belmont. The two 

 extreme varieties are, on the one hand, red, acid gneisses, composed of quartz 

 and microperthitic orthoclase with magnetite and varying amounts of dark 

 green-brown hornblende, and on the other, grey, more basic gneisses, made up of 

 plagioclase, orthoclase, aegerine-augite and titanite, with or without hornblende 

 and quartz. Sometimes one or the other of these attains considerable thick- 

 ness, but ordinarily the two are interbanded, the bands not exceeding a few 

 inches in thickness, and the one rock grading into the other. The resulting 

 rock is therefore well banded, but neither in structure nor composition does it 

 give any hint of a sedimentary origin. The customary dike-like bands of 

 hornblendic gneiss occur in all exposures of any extent. 



An interesting garnetiferous gneiss was found in the township outcropping 

 near the road one-half mile east of District School No. 6. It is a nearly black 

 gneiss and occurs interbanded with a reddish pyroxene gneiss of intermediate 

 composition. Garnets, which are so deeply colored as to be almost black, 

 make up nearly half the rock. In thin section they become transparent in 

 deep yellowish-brown tones. The resemblance to colophonite is strong. A 

 careful qualitive test made by Prof. E. W. Morley shows the presence of 

 titanium in small amount, and the color is probably due to it. In addition to 

 the garnet the rock is mostly made up of microperthite, but holds also a little 

 aegerine-augite, oligoclase and quartz. 



But two localities were found in Malone where the Potsdam was exposed 

 near the boundary. The first is along the Adirondack railroad about two 

 miles south of Malone, where 15' of red, thin-bedded, feldspathic sandstone are 

 exposed at the south end of a cut within 100 yards of massive exposures of 

 red, microperthitic gneiss banded with pyroxene gneiss. The dip is in the 

 normal direction and is not high, 10° to N. 35° W. ; the character of the 

 rock indicates the basal portion of the formation and there is no sign of 

 faulting. 



The second locality is a mile and a half distant and one mile east of School 

 No. (I. Here in a field south of the road, lying in ;ui embayment betw een 



