CLASSIFICATION OF ROCKS. 16 



retain in mind the surface distribution of the many different rocks or masses, which are found 

 in the district. As usual the first, or lowest in position, will be the first in order to be con- 

 sidered. 



Primary System. It forms a part of the great central elevated mass of the second district, 

 extending south and west, covering the northern part of Montgomery county, the north half 

 of Herkimer, the northeast corner of Oneida, and the whole of Lewis county, to the east of 

 Black river. The direction of its outer margin is nearly northwest and southeast through 

 l-icwis, Oneida, Herkimer, and the west half of Montgomery ; from thence it cui-ves to the 

 northeast. 



Taconic System. It is only found in a few points of the northeast part of Lewis county, 

 and requires no further notice at present. 



Champlain Division, is the first of the New- York system. It immediately follows the 

 Primary along the whole of its course, and with considerable regularity as to parallelism. 

 The upper member of the division extends beyond the south boundary of Montgomery, with 

 the exception of a comer at the southwest of the county. It ranges through Herkimer and 

 Oneida, from two to five miles to the south of the river, the limit upwards in those two coun- 

 ties well defined geologically by the Oneida conglomerate, which rest upon it as far as the town 

 of Westmoreland. Its breadth, south of the river, increases from Utica. It changes its 

 east-southeast direction at the south-southwest of Taberg village, for a north course, passing 

 out of the district by a curved line into Jefferson county, returning by a short curve again 

 into the district, and covering the northwest part of Oswego in the towns of Sandy-Creek, 

 Pulaski, and the skirts of the towns bordering upon the latter ones. 



Ontario Division. This is less regularly disposed in the beginning of its course than the 

 preceding one. It commences about where the county of Montgomery joins the counties of 

 Schoharie and Otsego, and extends into the fourth district. In the beginning of its course, 

 the Oneida conglomerate and Clinton group first appear coming out from under the base of the 

 Helderberg division, showing their northern outcrop. In going west they are joined by the 

 Niagara'group near Oneida county, and by the gray sandstone which first appears at Wood- 

 ruff's quarry to the south of Rome, the Medina sandstone not appearing in place to the east 

 of Oneida lake. The Ontario division widens greatly to the west of the Chenango canal, 

 covers tlie whole of Oswego county, excepting the part occupied by the preceding division, 

 passes to the south of Oneida lake, and extends thence in nearly a west course through the 

 district. 



The whole of the rocks of the division, from where it spreads out, show a surface arrange- 

 ment of great regularity ; the oldest to the north, the newest to the south ; the one following 

 the other in regular succession, which is the case also with all the rocks of the district west 

 of Oneida county. 



Helderberg Division. With the exception of the Onondaga salt group, this division is ex- 

 tremely well defined, being readily traced from the Hudson to Niagara river. With the 

 exception mentioned, and some valleys and ridges, it rarely exposes a surface of more than 

 three or four miles wide, in all its long course. The Onondaga salt group which forms the 



