PROF. EMMONS' VIEWS. 443 



We have already described the rocks of Snake Mountain in full (Sec Fig. 167) , but will 

 quote from a subsequent page of the American Geology , Prof. Emmons' views of the order 

 of rocks there : 



" The rocks between the lake and base of the mountain are lower Silurian. In the ascending order [at 

 the base], the rocks are calciferous sandstone, Chazy and Trenton limestones." The slates are not Utica 

 or Hudson River, but black slate. There are two faults, which we have indicated in Fig. 167. The rock 

 on top is the calciferous sandstone. The fractures " may be traced in the direction of the mountain axis, 

 four or five miles. The dip of the Silurian rocks is from ten to fifteen degrees ; of the taconic slates, 

 twenty-five to thirty degrees. At the northeast base of the mountain, perhaps three-fourths of a mile from 

 its summit, the slates crop out again, beneath the calciferous sandstone. 



' The summit of the mountain is calciferous sandstone, and is exposed in a perpendicular mural precipice 

 for four or five miles. The debris and fallen masses from this bold front generally conceals the underlying 

 slate, but it crops out beneath it at one or two places, while on the north side the whole slope is exposed, 

 and consists of one mass of slate from the calciferous sandstone to the bottom of the mountain. 



" The calciferous sandstone in this region is often red or chocolate color, especially the inferior part of it. 

 The gray variety at Burlington graduates into the red; and the Potsdam, which is used as a flagging stone, 

 at Burlington and other places, is usually brown or chocolate colored also. But the blue and gray with a 

 sparkling luster are found in the masses composing the mural wall at Snake Mountain. The junction 

 between the Taconic slate and Trenton limestone and its upper slates, or the Chazy limestone on the west 

 flank of the mountain, has not been observed. 



" The foregoing statements respecting the relative position of the rocks of this mountain seems to be all 

 that is required to establish the inference I have drawn from them. I need not dwell on the error which 

 has been committed [by myself and others] in regarding the chocolate-colored rock the Medina sandstone, 

 or attempt to show that the plication theory will not adjust the rocks so as to make the black and greenish 

 slates, the Utica slate or Hudson River group. It is one of simple dislocation, where the older rock on the 

 east side is elevated vertically higher and above a newer series on the west. The rocks, in this case, are 

 not engulphed upon the west side ; all the phenomena seem to prove that the whole mass composing the 

 mountain was raised vertically, but the east side was separated from the west by fracture, and elevated 

 above it. The series between the mountain and the lake occupy a much lower position than those upon 

 the flank of the mountain, proving that the latter have been broken from the former and elevated above 

 them. We find in Snake Mountain, a fact of common occurrence, a fracture at the base of the ridge or 

 mountain, and another running through it. Bald Mountain is another instance of this kind. In fine, with 

 respect to Snake Mountain, the position of the mass on the top of the mountain [Red sandrock] and which 

 covers the eastern slope, proves that it is an overlying mass, and an inspection of the junction of the inferior 

 beds which often jut over and beyond the slate immediately below, proves that it was deposited upon the 

 slate ; and as the two are unconformable, both in the amount of dip and direction, it is also evident that 

 they do not belong to one group or series. At this place the former is the base of the Silurian system. It 

 is very silicious generally, and might be called a sandstone, yet it is rather a mass intermediate between 

 the calciferous sandstone and the Potsdam sandstone. It is the same rock as that at Burlington, and at 

 Sharp Shins [Lonerock Point], two miles northwest of Burlington, where the same black slate crops out as 

 at Snake Mountain. Those who wish to satisfy themselves of difference between the Hudson River group 

 and the slate beneath the calciferous of this mountain, should explore the north end of it, where they will 

 find a mass of slate from top to bottom laid bare by a small stream which takes its origin immediately 

 beneath the jutting calciferous sandstone, and which by this little stream has been undermined for centuries, 

 and from which huge blocks have been, and are still, broken and carried down the mountain's side, and are 

 found distributed far and wide upon its northern and western sides. This slate is uncovered in a continuous 

 mass, between 700 and 800 feet thick. I was unsuccessful in a search of a few hours for fossils, and yet it 

 is similar to other exposures where I have found graptolites." 



