Plate 53 





JVI^W Y^ORK 



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A 



Pi'COJVM 



1>ENNSYLVANIA. 



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162. 



1- f^r«3nkiinFwnacc-U;S.(T-3. Fofio I6( 

 a-fXorritan " '9' 



7i-\(es^ point- 

 4-. phi'/odel/?hia 



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Key map of the principal Precambrian areas related to the Highlands of the 

 Hudson, showing the relative positions of the available geologic folios 



