618 NEW YORK STATE MUSEUM 



of sandstone become too thick for flagstones and the shale is in 

 thicker masses than below " (Hall, p. 228). 



About two thirds of the strata comprised within the typical 

 Portage section are represented by this middle division, the base 

 of which is at the river level at the lower end of Smoky hollow, 

 about 5 miles above the mouth of the gorge at Mt Morris, 

 G13' A.T. The upper limit, which for the purposes of this paper 

 is assumed to be about 27 feet above the crest of the upper 

 fall at Portage (1082' A.T.) is 50G feet higher than the base, 

 and the southward dip adds 208 feet, making a total of 714 

 feet for the thickness of the Gardeau division. 



With regard to the Portage sandstones, Dr Hall said on p. 228 

 "The thick bedded sandstones at Portage form the terminal 

 rocks of the group. . . The upper part consists of thick 

 bedded sandstones with little shale, while below the sandy lay- 

 ers become thinner, with more frequent alternations of shale." 



There are 182 feet of strata embraced in the section between 

 the assumed base 27 feet above the upper fall and the top of 

 the cliff south of the bridge and on the east side of the river. 

 A layer of hard blue shale, 2 feet thick, occurs 12 feet above 

 this assumed base, and another of similar character is found 

 52 feet higher; very thin shaly partings also separate some of 

 the harder layers, but with these slight exceptions the forma- 

 tion consists of layers of light bluish gray, medium fine grained 

 sandstone from 2 to 10 feet thick. The character of the rock 

 is remarkably uniform, varying but slightly in the degree of 

 hardness, some layers showing a tendency to be schistose or 

 flaggy; occasional concretions occur. 



"The Portage sandstone is succeeded by olive shaly sandstone 

 and shale and this by black micaceous slaty shale with septaria; 

 to this follow shales and coarse sandstones with fossils of the 

 Chemung group " (Hall, p. 248). These beds are not exposed 

 along the river but the lower portion may be seen in the 

 ravine of Wolf creek below Hopkins's mill at Castile, and the 

 upper part in the ravine of West Coy creek at Wiscoy, and in 



