586 



Report of the State Geologist. 



wild mass of Sentinel mountain, whose extension forms a notable ridgre to 

 the south. The highest point is 3,858 feet, but there are two or three others 

 that are nearly as high. 



The western part of the town is occupied by the noble peak of 

 AVhiteface mountain, whose isolated situation to the north of the other peaks 

 of the first rank, makes it in many respects the most striking of all the 

 Adirondacks. The view from its summit yields to that of no other in scope 

 .Hid grandeur. The summit is 4,872 feet above tide, so that AVhiteface is, 

 according to the maps of the United States Geological Survey the fifth in 

 altitude of the Adirondacks. Marcy, 5,844 feet; Mclntyre, 5,112 feet; Sky- 

 light, 4,920 feet, and Haystack, 4,918 feet, surpass it ; Dix, 4,842 feet, Basin, 

 4,825 feet, and Gothic, 4,738 feet, follow in order; but after Marcy and 

 Mclntyre all the next five have insignificant differences. Whiteface was 

 thought, for many years in the early part of this century', to be the highest of 

 all. To the southwest it drops off abruptly to lake Placid, but to the north- 

 east it is prolonged in a high ridge called Wilmington mountain, that reaches 

 3,500 feet. There is one pass at an altitude of 2,300 feet with a road running 

 through it from Wilmington to Franklin Falls. The drainage from the 

 western side of the range flows into the Saranac river. 



Series 1 and II, with my interpretation of thegneissoid rocks, are lacking 

 in the town, but I appreciate that the northerly extension of the Wilmington 

 range may be, perhaps, with fuller study, in part, at least, classed as such. 

 Professor Gushing has considered the extension over the town line as 

 belonging to the gneisses. The mineralogy of the rocks gathered by me is 

 given under the next topic. Series II may reach a short distance across the 

 line on the southeast. 



Series III. All along the easterly portion the rocks are green anortho- 

 sites or gabbro. No. 20 is a coarse pegmatite with pyrrhotite, and forms a 

 limited occurrence in the other massive rocks. At No. 24 the usual anortho- 

 site crops out, showing the familiar crushed structure. At No. 27 the rock 

 becomes more basic and like the gabbros and at No. 28 a granulitic phase w as 

 met, much the same as those described in my former report, page 469, from 

 the Weston iron mines near Keene. The mass of Sentinel mountain has only 

 been traversed by me around its base on the northerly extension. In Keene, 

 however, we have crossed it finding anorthosite all the way. On the 

 northwest side too we have studied its foot along the West Branch. Though 

 often gneissoid, it uniformly exhibits, so far as seen, the minerals of the 

 gabbros. 



