of Vermont and Canada. 103 
with the interstratified magnesian limestone to be ot great thick- 
ness. In the last exposure in the fields at the eastern side, I 
found the same form of Scolithus in abundance which character- 
izes the upper beds of the Potsdam in Canada. I could not 
find the exact position of the fault in this mountain, but at Buck 
mountain, which is of exactly the same structure, I think its ex- 
istence can be positively determined. This mountain is cut in 
two by a narrow valley crossing it obliquely near the southern 
extremity. The road through this valley runs to Vergennes, 
Following this road from the south, after passing through the 
wy in the mountain we cross a level meadow several hun- 
dred yards in width. Where the road leaves the meadow there 
Is a small ascent caused by an exposure of the Chazy or Black 
River limestone. On reaching this point the observer should 
turn to the right and go straight to the base of the mountain, 
Here the exact position of the fault can be seen, The sand- 
stone rises in a nearly vertical wall to the height of about 80 
feet. At the base the blue fossiliferous limestone di towards 
the cliff, but is separated from it by an interval o about 15 
or 20 feet—covered with broken stones. Here there is positive 
evidence of a dislocation, because in following along the base 
of the cliff, lower beds of the sandstone continually rise from 
low above the limestone. This occurs in consequence of the 
Strata of the two formations, not being tilted up in the same 
Plane, the sandstone on the east side of the fault dipping more 
‘o the south than the limestone on the west side. While 
upon the spot I thought I could see the edge of the fissure on the 
West side. I have pointed out this locality thus particularly 
with the hope that some other geologist may be dire e 
‘pot who may have more time to study the details than I had. 
The fault at Snake Mountain must have an upthrow on the 
ast side of about 3000 feet, for it is equal to the whole thick- 
a. 33.0f the 700 feet of black slates, the whole of the Potsdam 
Calciferous, Chazy, Black River, and part of the Trenton. The 
Mountain itself is at present only about 1000 wm oe than the 
‘trounding plain, having, no doubt, been reduced by denuda- 
Hon, _+ appears to me quite certain that there must be a great 
t of ‘slate beneath the Potsdam in this region, otherwise, 
this €normous fault would have brought up the Laurentian 
v9 But no trace of it is seen anywhere about the mountain 
r°pt in the the usual forms of loose ers. , 
I shall conclude with a list of the fossils discovered at the lo- 
ve mentioned, I place the sandstone and limestone 
th are more interested in the nomenclature of the formations 
an 
be just and mo 
