ELIZABETHTOWN AND PORT HENRY QUADRANGLES 2^ 



sions appears on the east and west road. To the observer in the 

 field this appears hke a pronounced intrusive granite, sheared more 

 or less into a gneiss, but different from both the syenite series an(' 

 the Grenville. The microscope reveals quartz, microcline, micro- 

 perthite and hornblende. It is, therefore, not so sharply contrasted 

 with the acidic members of the syenite series as is the Bulwagga 

 occurrence, in that it has microperthite and hornblende, but it has 

 microcline and in the ledges it looks unlike the syenite series. 



There are two other small areas colored for granite, and lying 

 southwest of Westport. Both of these are coarse gneisses, reddish 

 in color, with their quartz and feldspar in little, interleaved lenses, 

 up, to an inch in length. No microscopic slides have been prepared 

 and the rock might perhaps be justifiably placed with the syenite 

 series. In the field it was believed to be different. 



Besides the occurrences actually colored, there are one or two 

 others deserving mention. In the gorge of Mill brook, just north 

 of Port Henry, and a short distance above its mouth, there is a 

 band of white granitic rock, several hundred feet thick, in the 

 midst of the Grenville limestones. It is obviously much crushed, 

 is dense, white and granitic in aspect. Under the microscope its 

 components are microperthite, microperthitic microclinCj quartz, 

 jlagioclase, biotite, garnet and zircon. It is difficult to decide 

 whether this is an intrusive granite or an altered sediment, but the 

 former is the more probable. 



A mile west, up Mill brook, is the old Lee mine ; its walls are a 

 red granitic rock now strongly gneissoid. IMuch the same rock 

 appears in the walls of the old Essex county ore bed in the northern 

 slope of Bulwagga mountain, but all these last three have been 

 colored in as Grenville. Again in the ridge, an eighth of a mile 

 north of the east end of Crowfoot pond, granitic gneisses again ap- 

 pear, different from the run of the syenite series, but no special 

 color has been given them. 



Anorthosites 



The anorthosites are believed to be the oldest of the eruptives. 

 They certainly followed the sediments because of the included 

 masses which will be later described. They preceded the Split 

 Rock falls type because we find inclusions of them in the latter. 

 They are believed to be older than the syenites, not from any posi- 

 tive evidence in the area under discussion but because they have 

 been clearly shown to be such by H. P. Gushing in the Long Lake 



