26 NEW YORK STATE MUSEUM 



though somewhat darker than the normal syenite on account of a 

 larger percentage of dark minerals, moderately gneissoid, and with 

 some small garnets. At times there are streaks of dark, basic 

 gneiss (presumably Grenville) more or less fused in, giving the 

 rock something of a wavy or contorted aspect and suggesting the 

 possibility that the basic syenite here has been produced by assimi- 

 lation of such dark gneiss by the syenite magma. Ledges on the low 

 mountain ridge to the east and southeast of the falls are very similar. 



The rock of the Owl's Head mountain area (no. 44, table 4) is 

 dark, greenish gray when fresh and weathers to a deep brown. It 

 is very homogeneous, medium grained, clearly gneissoid, and usually 

 rather rich in dark minerals though without garnets. The darker, 

 portions have a decided gabbroic look though not like the later 

 gabbros of the quadrangle. Occasionally a small phenocryst of 

 plagioclase stands out in the medium-grained, granulated niatrix. 



The area northeast of Long Lake village borders the anorthosite- 

 gabbro and seems to form a transition between that rock and the 

 normal syenite, though such a transition is not positively demon- 

 strable as above discussed in connection wath the anorthosite-gabbro. 

 Exposures occur only close to the lake either side of the anorthosite- 

 gabbro, the rock (nos. 55 and 56, table 4). being fine to moderately 

 coarse grained, greenish gray weathering to brown, clearly gneissoid 

 and fairly rich in dark minerals. Sometimes there is a suggestion 

 of a porphyritic texture. A few bands of amphibolite parallel to 

 the foliation occur in the rock along the lake shore south of the 

 anorthosite-gabbro. 



The Triplet Hill mass is probably only a westward extension, 

 under the lake, of the area last described, the rock being very simi- 

 lar though at the summit of the hill some of the rock is rather dis- 

 tinctly porphyritic. 



A very small body of basic syenite shown on the map northeast 

 of Long Lake village is only a wide band parallel to the foliation 

 of the syenite and not sharply separated from it. The rock is of 

 decided igneous aspect, rather hornblendic and with occasional 

 garnets up to more than an inch across. Apparently this rock has 

 been produced by the assimilation of some Grenville hornblende- 

 garnet gneiss by the syenite magma. The rock bears a very close 

 resemblance to a definitely proved assimilation product of this sort 

 at the garnet mine on Gore mountain near North Creek in Warren 

 county. 



Granitic syenite. The granitic syenite is really only an acidic 

 phase of the syenite in which the quartz content lies approximately 



