SUCCESSIVE DEPOSITS IN THE APPALACHIAN REGION 425 



the Queenston shale. According to Foerste/ these red beds rest on suc- 

 cessively higher Eichmond beds northwestward in the Manitoulin Islands. 

 The upper 103 feet of red marly sandstones of Cabots Head will likewise 

 be shown to be Upper Medina, which is thus included as a wedge in 

 marine Clinton. 



Eeturning to New York, we find the Oswego sandstone capping the 

 Hudson series. At Niagara this sandstone is 75 feet thick and westward 

 of this it soon disappears. 



Near the eastern end of Lake Ontario and on the Salmon Kiver this 

 sandstone is well shown in many exposures. On the Salmon Kiver above 

 Pulaski, where it forms the fall 107 feet in height, its thickness some- 

 what exceeds the height of the fall. It here rests on the Lorraine shales 

 and appears to grade down into them, thus indicating that they form 

 with this shale a continuous depositional series. Fossils are rare in this 

 rock, but they have been found 40 and indicate that these sandstones were 

 in part at least submarine. Trails and impressions of the type generally 

 referred to as fucoidal are common in certain layers. Irregularity of 

 bedding is another feature shown in these sandstones, while in some sec- 

 tions the sandstone is seen to contain shale lenticles, which represent' 

 broken layers of lutaceous sediment subsequently incorporated in the de- 

 posits of sands. These features indicate that the water in which these 

 deposits were forming was very shallow, and indeed much of the material 

 suggests subaerial rather than a submarine origin. 



In attempting to trace the source of the material composing the Oswego 

 sandstones, we must first carefully consider the nature of the material 

 itself. Nearly pure quartz, such as makes up this deposit, must have its 

 ultimate source in some crystalline quartz-bearing formation. Tt is true 

 that such a source need not be a direct one, for an older quartz sandstone 

 may be reconstructed, thus becoming the direct source of the material. 

 We must then look for an older sandstone or a crystalline area as the 

 source of the material. The nearest crystalline area to the present out- 

 crops is, of course, the Adirondack old land, and only a little farther 

 removed we find the crystallines of the Canadian shield. II' either or 

 both of these deposits were the source of the material of the Salmon 

 River (Oswego) sandstone, it is to be regarded as a remarkable fad that 

 the material is so thoroughly assorted and of SO uniform a grain, con- 

 sidering the nearness of the source of supply. One might, of course, cite 

 the Potsdam sandstone as an example of a pure quartz sandstone resting 



30 Gepl. Soc. Am. Washington Meeting, preliminary outline of papers. 

 40 L. Vanuxein : Report on the Third District, Now York. p. 60. 



