66 GEOLOGY OF THE TmRD DISTRICT. 



the dam, a more sandy and rather lighter colored mass is seen, holding a higher position, 

 evidently the terminal part of the division in that region. This portion abounds in the Alter- 

 nate stropiiomcna, none of which, in any of the localities where the wiiole could be seen, was 

 found below that position. The same ferruginous stains also mark the upper portion when 

 greatly altered. 



The first locaUty in the Mohawk valley where tlie sandstone shale of Pulaski appears, is at 

 Talcott's and Comstock's quarries about two miles to the south of Rome.. About ten feet of 

 the mass is exposed, the larger portion of which is good building stone, and is quarried for 

 Rome. It is far more sandy than any of its other localities, and its colox is a light grey. 

 It is not in regular or straigiit layers ; the divisions arc caused by shale of the usual bluish color, 

 cither uniformly spread over the surface of the sandstone, but in paitches of no great extent, 

 or irregularly intermixed with it, and sometimes so thin as to be a mere coating. The fossils* 

 so characteristic of the division at Pulaski and other localities north and west of the Mohawk, 

 are here extremely abundant ;, such as the Carinate pterinea, the different species of Cypricv- 

 ditcs, the Alternate strophomena, the Ornated cyrtolite, and other testaceous fossils and some 

 fucoids to be noticed in the Report of the fossils of the State. 



The Alternate strophomena occupies, as at Pulaski, the liighest part of the mass. It. 'is 

 in very thin layers of sandstone, and with the same altered character as at the former place. 

 Fragments of this division of the group are numerous in the enclosures of the field, for some 

 distance from the quarries. 



To the west of Rome, extending north through Lewis county, the Pulaski shale covers a 

 large portion of the west side of the range of the Hudson-river group, varying in breadth from 

 four to six and more miles. Throughout its whole range its fragments are numerous, and 

 usually show one or more specimens of its peculiar fossils. Among the many localities where 

 the division may be seen to advantage, is the creek at Tabcrg village, and at the point of rocks 

 on Fish creek, about seven miles above the village. At the latter place, it forms a bluff about 

 twenty feet high, where two streams meet at an acute angle, and it is also found in the bed of 

 the creek. Its range is rather to the east of the north branch of the Mohawk river, forming 

 a low bank at Preston's saw-mill, and appearing also in a well at Tuttle's farm, to the north- 

 cast of the mill. 



In Lewis county, no localities were observed of particular note ; it ranges to the west of 

 the lower slates, appearing in numerous places along their rai)ge, and approaching nearer and 

 nearer, going north, to the line of the Utica slate. On Deer river, about three miles to the 

 west of Copenhagen, the shale and sandstone appears at Adcock's mill, and contains Tortoise 

 orthis, Semioval strophomena, etc. Where the road crosses the river from Rodman to Low- 

 ville, seven and a half miles from Copenhagen, the Pterinea and other fossils of Pulaski are 

 seen near the bridge. 



The most numerous points where the Pulaski rocks are exposed, arc in the northwest part . 

 of Oswego county, whecp it forms the surface rock, and where numerous creeks and other 

 water courses traverse its layers, exposing their surface and edges. Among these arc Deer 

 and Little Sandy creeks, the latter being a good point for examination, bolii at Washington- 



