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NEW YORK STATE MUSEUM 



is, however, also possible that a thin edge of the Utica formation 

 reached here around the southern Adirondacks, but was again 

 eroded before the Indian Ladder sea crept over this region from 

 ■ the south. This latter formation consists, at the Indian Ladder, 

 mainly of soft shales with some sandstone and calcareous bands, 

 and seems to have been deposited in a slightly deeper sea than 

 the Schenectady beds. 



As we have seen before, there are exposed in the shale belt rocks 

 of two entirely different sets of formations which represent sedi- 



Fig. 15 Diagram of time relations of formations of the eastern and west- 

 ern troughs on the Saratoga-Schuylerville quadrangles. Shaded intervals 

 indicate probable emergences 



ments deposited in two different troughs, the western or lower 

 Mohawk trough and the eastern or Levis trough; and if the 

 Georgian beds represent a third trough (see above, page 114), even 

 sediments of three basins. 



