POSTGLACIAL MANGANESE IN COLUMBIA COUNTY, 



NEW YORK 



BY NELSON C. DALE 



At the request of the State Geologist the writer has undertaken 

 the investigation of these ores. 



The urgent demand for manganese as the result of the interrup- 

 tion of our imports from Brazil, Russia and India in consequence 

 of the war has stimulated the search for new deposits, as well as 

 more detailed investigations of the possible utility of hitherto known 

 deposits of low grade. 



Bog manganese was long ago reported from various places in 

 Columbia county (1:54) and it seemed well to reexamine these 

 occurrences. According to W. W. Mather in his report of the First 

 District Survey, 1836-42, " in the counties of Columbia and 

 Dutchess 50,000 tons of manganese could be procured without any 

 great expense, if carefully prepared." He also stated that some of the 

 bog manganese showed on analysis as high as 68.5 per cent manganese 

 oxide and less than 5 per cent silica. At the direction of the State 

 Geologist the writer has devoted most of the summer of 191 7 to 

 this work. The results of this investigation, though not in any 

 way confirming the quantitative results of Mr Mather, are herewith 

 published as a matter of record and as an account of the manner of 

 the occurrence and the genesis of postglacial bog manganese. 



Physical Features 



The manganese district of Columbia county includes certain 

 swamps or marshes of small area, 1200 to 1400 feet in elevation, 

 scattered throughout a north-south belt 25 miles long and 5 to 6 

 miles in maximum width. This area of 125 or 150 square miles 

 lies among the western foothills of the Taconic range, some 12 miles 

 south of the Rensselaer plateau and 15 to 20 miles east of the Hudson 

 river, principally in the townships of Canaan, Hillsdale and Ancram. 



In practically all the localities the manganese-bearing bogs occupy 

 small depressions in the interhill saddles or divides, or in terracelike 

 benches at the foot of hills usually at about the same elevation, 



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