ROCHESTER AND ONTARIO BEACH QUADRANGLES II 



points where the rock is not too badly decomposed, there are some 

 times found white and green bleached bands usually occurring at 

 right angles to the bedding planes. Along the shore of Lake Ontario 

 some of the harder beds may be seen. One such exposure is shown 

 at Windsor Beach and another at Forest Lawn. 



Throughout the time of the deposition of these red shales, the 

 conditions were very unfavorable to the existence of life in these 

 waters, and there have been no fossils found in the beds. 



Upper Medina sandstone and shale. The j^assage from the lower to 

 the upper division of the Medina marks a change in the character of 

 sedimentation, brought about, in part, by a greater expansion of the 

 sea. This change was accompanied by a clearing of the waters and* 

 the introduction of marine life. Li central New York the lower divi- 

 sion extends as far east as the vicinity of Rome. The upper division 

 represented by about loo feet extends 40 miles farther east nearly 

 to Cherry Valley. To the east of Oneida county, this upper division 

 has usually been referred to the Oneida conglomerate. This con- 

 glomerate has generally been correlated with the lower division of 

 the Medina and considered as the stratigraphic equivalent of the 

 Oswego sandstone. Since, however, this conglomerate forms the 

 overlapping eastward extension of the Medina, it can only represent 

 the upper part. From the close proximity of the Oneida to the 

 Clinton wherever the conglomerate is found, and from the presence 

 of the fossil F u c o i d e s h a r 1 a n i, which is restricted to the upper 

 Medina, the Oneida conglomerate is here considered a local facies 

 of the upper Medina. In passing west from Oneida county, the 

 upper Medina becomes less conglomeratic, though in the Rochester 

 section pebbles are found in some of the upper layers. West from 

 Rochester and in the Niagara region, the lower division is followed 

 by about 25 feet of gray quartzose sandstone. This layer contains 

 the remains of Lingula cuneata which is also found in the 

 upper Medina at Rochester. This sandstone appears to correspond 

 approximately to the base of the Medina of the eastern sections, 

 both occurring at a little more than 100 feet below the base of the 

 Clinton. In the Niagara region this sandstone is followed by a 

 series of shales and thin-bedded sandstones. The shales are similar 

 to those of the lower Medina and indicate a temporary return to 

 conditions of sedimentation similar to those which prevailed during 

 lower Medina time. The uppermost stratum of the Medina is 



