LOWER SILURIAN SYSTEM OF EASTERN MONTGOMERY CO. 467 



4 Thin to thick bedded limestone, characterized 

 by abundant individuals of Rafinesquina 

 alternata. Trenton. 38'== 402' 



3 Dark colored lumpy limestone, characterized 

 by Columnaria alveolata. Black river. 9'= 364' 



2 Dove colored very fine grained limestone, 

 characterized by Phytopsis tubulosa. 

 Birdseye. 5'= 355' 



I Thick to thin bedded, flinty, arenaceous lime- 

 stone. Calciferous. 35o'= 35o' 



Discussion of maps and sections 



On the geologic map of the state of New York published in 

 1844I the Calif erous is shown as extending northeasterly from 

 Rotterdam and westerly along the Mohawk on the south side of 

 the river, extending a mile or more to the south. On the map 

 which accompanied the New York mineral exhibit at the Colum- 

 bian exposition,^ the Calciferous and Trenton stages are not separ- 

 ately mapped. The eastern and southern boundary of the lower 

 Ordovician is indicated as extending from Hoffmans to West 

 Charlton and northward^ and on the south side of the Mohawk 

 for two miles south of Pattersonville and thence westerly along 

 the Mohawk joining that at Tribeshill. The Utica-Hudson river 

 terrane adjoins the Calciferous-Trenton along this boundary line 

 and also covers the region west of Amsterdam and north of Aiken, 

 between Amsterdam and Tribeshill. On the large map recently 

 published^ the Calciferous and Trenton stages are separately 

 mapped. The Calciferous extends from Hoffmans (not from Hofif- 

 mans as located on the above map for it is there wrongly located, 

 being too far east) north to Galway and northward, and westerly 

 in a narrow belt along the south side of the Mohawk to opposite 

 Aiken (three miles west of Amsterdam). The Trenton forms a 

 small patch north of Hofifmans and extends along the southern 



^The full title of this map Is, "Agricultural and geological map of the state of New 

 York by legislative authority 1844." 



^Economic and geologic map of the state of New York showing the location of 

 its mineral deposits, by Frederick J. H. Merrill, director New York state museum, 

 1894. 



'Geological survey of the state of New York. Preliminary geological map of New 

 York exhibiting the structure of the state so far as known, prepared under the direction 

 of James Hall by W. J. McGee. Published by authority of the legislature of the state 

 of New York. Printed by the U. S. geological survey. J. W. Powell, director, 1894. 



