l6 NEW YORK STATE MUSEUM 



extremely significant in that they prove that the gneisses were 

 metamorphosed before they were picked up by the anorthosite, and 

 that this foliation, running as it does in all directions, is not the 

 result of pressure after the blocks were caught in the intrusive. 

 It leads one to infer the comparatively late date of the entrance of 

 the anorthosite and the existence of a long period of time, marked 

 by regional metamorphism before its appearance. 



These inclusions are also reminiscent of observations made in the 

 preliminary work of 1893, as set forth in the Report of the State 

 Geologist for 1893, pages 440, 468 and 469. Along the road run- 

 ning northeast past Chapel pond, and amid what was believed to 

 be at the time universal anorthosites, a small ledge was found of 

 a dense, fine-grained rock whose composition was shown by slides 

 to be much the same as that of the famous Saxon granulites ; 

 that is, it consisted of quartz, orthoclase and garnets. Much sur- 

 prise was felt at the time that such an unexpected exposure should 

 appear. Undoubtedly it was one of the included masses of old 

 Granville sediments so large as not to expose its edges in the few 

 feet visible. The inclusion is now exposed for many feet along a 

 fault and crushed zone, used as a borrow pit for the highway. A 

 curious additional phenomenon which was noted for several inclu- 

 sions near Owls Head, larger than those mentioned above, was 

 shown to the writer by the late Erastus Hale of Keene Center. Mr 

 Hale was an experienced surveyor with the dipping needle. Around 

 the edges of the inclusions there is at times very strong attraction 

 for the dipping needle, reaching 90°, but the amount changes within 

 a few feet, from 90° positive to 90° negative. Apparently along 

 the borders of the included blocks there must have been developed 

 some small masses of strongly magnetic iron ore, even though we 

 could not see them. At times the needle was influenced by their 

 south polar ends, at times by their north polar. 



A gneiss was collected in the field on the hill just east of the East 

 branch and one-half mile south of the northern edge of .the sheet. 

 It was encountered in ascending, from the undoubted Grenville of the 

 river bottom and was believed at the time to be a metamorphosed 

 sediment. In thin section it revealed greatly strained rnicro- 

 perthitic orthoclase and microcline, with irregular shreds of brown 

 hornblende and pale green or colorless pyroxene. A little magnetite 

 also appears. The rock is illustrated in plate 10. 



The mineralogy is that of the syenites and the exposure may well 

 represent an intrusive mass of this rock, which has penetrated the 

 anorthosites in this area. In spite of a careful search decisive evi- 



