CLINTON COUNTY. 
315 
when it actually reaches the lake near the Provincial line. The potsdam sandstone prevails 
immediately west of this outcropping edge. But I do not intend to convey the impression that 
this outcrop still pursues this north-northeast course : it has its limit here ; for I find that 
according to the known geological structure of the northern slope into Canada, this line of 
outcrop sweeps around to the west; and upon this there is the same succession of rocks, in 
advancing north again, as we have upon and adjacent to the shore of Lake Champlain. For 
example, nine miles south or southwest of St. Johns, the identical encrinal masses of the 
chazy rocks crop out, and are quarried for building stone. The fact, too, is brought out by 
the dip of the potsdam in Mooers and Ellenburgh ; and from these lower masses the formation 
or group runs up to the loraine shales, which are fully formed at Laprairie, and are geologically 
the highest masses on the river south of Quebec. 
I have now defined the western outcrop of the calciferous in Clinton county ; and as the dip 
of the rocks is generally easterly, or rather northeasterly, we shall have a belt of this rock 
parallel with that of the potsdam sandstone. It is, however, narrow : at Chazy, it is only 
eighty rods wide; and it probably will not average a mile in width from Unionville to Cham¬ 
plain, the whole length of the county. 
From the preceding observations, it will appear that the calciferous sandrock in Clinton 
presents the same general characters as elsewhere. There are wanting, however, one or two 
varieties which are found at other places; for instance, the cherty mass, and that which 
abounds in geodes of crystals. Both of them are found at Whitehall, and also at Essex, 
though at the latter place it is not largely developed. The difference, however, between this 
rock in Clinton, and as it exists in the Mohawk valley, is, that in the former a greater pro¬ 
portion of calcareous matter enters into its formation, and in the latter, silex predominates. 
Still the same general characters, as remarked above, appear in each region ; there is not, in 
either case, so great a disproportion as to give the masses aspects which are specifically different. 
Chazy Limestone. 
The chazy limestone, in the ascending order, succeeds the calciferous, which, as I shall 
be able to show, has been separated from the preceding for substantial reasons. 
It is a dark-colored, thick-bedded limestone, and as it formed at Chazy, is quite rough and irregular 
in its exterior. Its planes of bedding are very indistinctly defined and uneven, and hence never separating 
in smooth surfaces. Its general structure appears concretionary, hut ill defined. Chert or hornstone is 
often diffused through it, particularly in those places where fossils occur, many of which are siliceous 
casts. 
The characters above given are not absolutely uniform; as at Westport in Essex, it is a 
tolerably even-bedded rock, and though not free from siliceous matter, still it maybe quarried 
and employed for many purposes, being susceptible of even and handsome surfaces. But at 
Chazy, the greater part is too irregular and uneven, and too much filled with nodular masses 
containing chert, to be employed economically. The best exhibition of the rock is only a few 
rods west of the village, where it forms several important ridges running nearly north and 
south. 
