JEFFERSON COUNTV. 381 



But three or four uplifts in succession, varying from twenty-five to thirty-five feet in height, 

 in which the difTcrent strata composing tiic rock appear, furnish an opportunity for an exami- 

 nation of a large portion of the rock. Tiiis mass, which succeeds the potsdam sandstone, 

 continues the surface rock only one mile and a half, when it is succcded by the birdseye. 

 It dips generally to the south, and its principal natural joints run north and south, but the 

 ranges of low hills of this portion of the county have a direction northeast and southwest. 

 From this point, about four miles south of Theresa falls, the calciferous extends to the east and 

 west ; and taking the wiiolc mass into view, it forms a belt traversing the entire widtli of the 

 county, from near the Natural bridge on the cast, to French creek on tiic west. This belt is 

 from one and a half to four miles wide ; its northern outcrop resting on the potsdam sand- 

 stone, while at the south it passes beneath the birdseye. Not far south from the first uplift 

 which exposes the calciferous sandrock, on the road leading from Theresa to Watertown, the 

 drab-colored layers form a large proportion of the mass. They contain masses of calcare- 

 ous spar and sulphate of strontian, and disseminated particles of sulphuret of iron. These 

 layers appear to be adapted to form the usual hydraulic lime. The portion of the calciferous 

 exposed to inspection upon this road, is about si.xty feet thick ; and so far as my observations 

 extended, it is destitute of fossils. The development of this rock in this county appears to be 

 confined to the lower portion, or we do not discover those beds which, in other places, belong 

 to the upper part. Some of them may exist concealed beneath the drift and soil. 



The Calciferous sandrock, as it is exposed between French creek and Depauville. 



On this route we traverse this rock from west to east. The first appearance is one and a 

 lialf miles east of French creek, on the summit of a hill ; it here succeeds the sandy variety 

 of the potsdam, which has already been noticed. The fucoidal layers make their appearance 

 first ; they are very siliceous, and most of these vegetable forms are casts, and destitute of 

 an organic structure. By far the largest portion have disappeared, leaving simply cylindrical 

 but branching perforations in the rock. This mass is about ten feet thick. 



Proceeding east, we soon reach the drab colored layers of the rock, quite similar to those 

 already spoken of as existing on the Watertown road. Here they contain a greater amount 

 of sulphate of strontian and calcareous spar. The rock continues to Depauville, where it is 

 quarried for hydraulic lime. The lower strata at this place are evidently quite siliceous, or 

 sandy. At Depauville the birdseye appears, but it only occupies the highest grounds. The 

 union or junction of the two rocks is therefore formed at this place. 



On a review of the characters of the calciferous sandrock, as it presents itself in tiie diffe- 

 rent portions of the Second district, we find that it is uniform in its composition and structure. 

 Corresponding portions agree in most respects with those which have been noticed under the 

 different counties. The fucoidal layers every where are the same, with the exception of a 

 mass at Chazy, which being much more argillaceous than usual, may possibly be a distinct 

 additional mass. The drab colored layers are specially uniform, being in all respects iden- 

 tical both in composition and color, and also destitute of fossils. When portions of this rock 



