ONEIDA CONGLOMERATE. TS 



9. ONEIDA CONGLOMERATE. 



Shawangunk Conglomerate. Millstone Grit of Eaton. Grey Band of Rochester ; being 

 a sandstone to the west, and a conglomerate and sandstone to the east. 



(No. 5. Pennsylvania Survey.) 



This is the oldest distinct conglomerate rock or mass of the third district. It is the same 

 with the Shawangunk Conglomerate ; its position being so well defined in Oneida county, is 

 the reason why the name Oneida Conglomerate is retained. It is composed of quartz pebbles, 

 rarely exceeding three-fourths of an inch in diameter, and of white or yellowish quartz sand. 

 In some localities, there is some interposed greenish shale. 



The rock is first seen at the east end of Herkimer county, on the south side of the Mohawk, 

 exhibiting merely its northern outcrop, and extends west through Oneida to Stony creek, the 

 creek being the last place where it is seen as a solid ledge, from thence to Cayuga county ; 

 but its blocks are very numerous on Oneida lake, and on the bank in the rear of the lake, to 

 the east of Cleaveland, formerly Constantia. From their number, large size, and not being 

 water-worn excepting a few near the level of the lake, and being in the line of the direction 

 of the parent mass in Oneida county, they cannot be far from their original position. 



The conglomerate, in small blocks, occurs in the alluvion above the dam in the village of 

 Oswego, and similar blocks are occasionally met with on the surface. For three or four miles 

 to the east of Oswego, they are rather abundant ; and near the village of Scriba, on the road 

 to New-Haven, they are quite numerous, and continue along the road for a mile or two, 

 gradually diminishing in number farther east. Beyond Oswego county, the pebbles of the 

 conglomerate disappear, sand taking its place. It reappears as a ledge in two quarries in the 

 north part of Cayuga county, but without pebbles, having the same character as a sandstone 

 as at Rochester, and accompanied by a similar green shale. Its greatest thickness is in 

 Oneida, being from thirty to forty feet, and diminishing as it recedes from thence. The source 

 of its materials was to the south, being of great thickness at the Shawangunk, and of still 

 greater thickness in the Blue ridge of New-Jersey and Pennsylvania. 



The conglomerate rests upon the Frankfort slate and sandstone in Herkimer, the base of 

 the Pulaski shales in the eastern part of Oneida, and the Pulaski shales and grey sandstone in 

 the western part. In Cayuga the conglomerate must rest upon the red sandstone, the two 

 rocks being near to each other, and no intermediate one there existing, but the space between 

 them is covered so as to conceal the contact. Such also would be its position in Oswego, 

 were the whole of the alluvial of the north border of the lake removed, and the conglomerate 

 left in its original position. 



The conglomerate forms a part of the Clinton group, the next mass in order of superposi- 

 tion. It was separated, as being a convenient point for division, and from the importance 

 which was once attached to this rock, having been confounded with the conglomerate of the 



