HUDSON RIVER GROUP. 63 



To the west, at the lower mill below Vanhornsville, and also at Yawheiur creek to the 

 east of Mr. Shawl's, the water falls over the conglomerate and the slate, into the deep gulfs 

 excavated in the slate by the waters of the creeks. At the mill, numerous graptolites, the 

 G. • • * *, exist in the slate at the top of the mass, which was uncovered in making its 

 foundation. Thin layers of sandstone in alternation with the slate, being a common character 

 of the mass, appear in the gulf ; towards the bottom of which, near the depth of one hundred 

 feet, it is more coarse, and there assumes the character of the thick layers in Schoharie. 



The points further west, where the slate also passes under the overlying rocks, enume- 

 rating them in their geographical order, are first, by the side of Wicks' store, in the brook, 

 which exhibits but a small excavation in the slate ; in Fulmer valley, it shows itself in many 

 points, the greater part of the valley consisting of the slate ; in Steel's creek and Myers' creek 

 back of Frankfort, whence the name given in the second year of the survey. The latter creek 

 aflfords the best opportunity for observing the edges of the slate, which extend like a wall for 

 two miles up the creek. It shows thin layers of sandstone, at variable distances from each 

 other, separated by slate. A good point also is at Starch-factory creek, and another at the 

 hiU wliich projects nortli between the creek and Utica ; and a still better one presents itself in 

 the long and deep gulf to the south of the Minden turnpike, the entrance to which faces the 

 southeast end of the city. Its whole length and depth is excavated in the slate, which disap- 

 pears under the Oneida conglomerate, over which the water falls at the head of the gulf. 

 The mass in the gulf consists of slate, and sandstone slate, none but very thin layers being 

 observed. Towards the upper part of the slate, the Cryptolithus and the Triarthus were 

 found, the latter not more than one-third of the usual size ; and also two or three thin bi- 

 valves, quite small, not yet described, figured or named. These fossils appeared to be rare ; 

 and from their small size, could readily have been passed unnoticed. Only one specimen 

 of the Triarthus was found, and but two of the Cryptolithus. 



The last place to the south of the Mohawk, where the Frankfort slate appears in the hill- 

 side, is under the conglomerate on the farm of Mr. Mason, on the hill to the east of New- 

 Hartford Centre. 



North of the Mohawk, it covers the high hill which extends through the towns of Schuyler 

 and Deerfield, surrounded by Utica slate in all directions. The range which turns north from 

 the Mohawk, shows itself at Ridge's mill to the north of Rome, and in some of the small 

 streams which flow east into the Mohawk and its east branch, Lansing-kill. Through Oneida 

 and Lewis counties, its range is undisturbed ; it presents no change of character, and appears 

 in all the water-courses of the latter county which flow east, over the limestone, to the river. 



The Frankfort slate and sandstone, though so thick a mass, and placed between two such 

 highly fossiliferous rocks as the Trenton limestone and the sandstone shale of Pulaski, is 

 remarkably deficient in organic remains, excepting in graptolites. In the third district they 

 are, however, but few in number when compared with the first district ; there they exist in 

 great number, in excellent preservation, showing from four to five species, and are found in 

 many locahties. The illustration of this rock by its graptolites is therefore left for the geolo- 

 gist of that district. We shall merely state that the ramose nature of two of the species of 



