LOWER SILURIC SHALES OF THE MOHAWK VALLEY 69 



Note to diagram 



Doctor Ulrich and the writer have represented the stratigraphic 

 results here obtained in the adjoined diagrammatic section of the 

 Eopaleozoic formations of the Mohawk valley. The relations of 

 the formations below the Trenton are reproduced as established 

 through former investigations by E. O. Ulrich, H. P. Gushing and 

 the writer. The relations of the Canajoharie and Schenectady beds 

 to the Trenton limestone of the Trenton Falls basin are represented 

 as described here. The upper Trenton limestone is drawn as 

 abruptly terminating at the eastern edge of the Trenton Falls basin, 

 because Doctor Ulrich failed to find it between Rathbone brook 

 and Middleville, and the Utica shale is shown to diminish rapidly 

 eastward, especially in its lower portion. The amount of its east- 

 ward extension in the Mohawk valley at present is not fully known. 

 The Schenectady beds may at their top reach into the upper Trenton 

 age and this transgression into the upper Trenton is indicated by 

 the dotted line. The Indian Ladder beds appear as a lenticular 

 body, since their main extension is in northeastern direction, crossing 

 the east-west sectional plane in a very limited area. 



Doctor Ulrich holds from his investigations that the Levis is the 

 second trough east of the Schenectady basin and that the Chazy 

 bay intervenes but is now covered by the overthrust Levis deposits. 

 We have not attempted to introduce this condition on the diagram 

 to the right of the permanent barrier because the exaggeration of 

 the vertical scale would not permit its intelligible representation. 

 The overthrust condition, however, which has brought the forma- 

 tion of the Levis basin in contact with those of the Schenectady 

 basin in Albany and Saratoga counties, is indicated by the arrows 

 showing, the direction of the movement. We have further tenta- 

 tively placed in the series of the Levis channel formations (mainly 

 graptolite shales) a limestone outcropping about Bald mountain. 

 From fossils collected last summer by the writer it is determined as 

 of upper Beekmantown age. The Rysedorph Hill conglomerate, 

 which also outcrops at various localities, belongs with the Levis 

 channel graptolite beds and probably lies between the Normanskill 

 shale and Snake Hill beds. 



Bibliography 



(1) 1842 Vanuxem, Lardner. Geology of New York; Report on the 



Third District. 



(2) 1843 Mather, W. W. Geology of New York; Report on the First 



District. 



