THE IRON SERIES (IN PART). 81 



A gap occurs in the succession of the deposits across southern 

 New York and New Jersey, although a few minor ones are known 

 in the western part of the latter State, in the magnesian limestone 

 of the valleys between the hills of gneiss. 1 



2.01.19. In Lehigh County and to the southwest through York 

 County, in eastern Pennsylvania, the limonites are again developed 

 in great amount, and run southwesterly, with few gaps, to Alabama. 

 It is in this portion that the " Great Valley " (called also the 

 Cumberland Valley, or Valley of Virginia) is especially marked. 

 Wherever the great limestone formation, No. II. of Rogers, is 

 developed the ores are found. This corresponds to the Calciferous, 

 Chazy, and Trenton of New York. Limonites also occur still 

 lower in the Cambrian at about the horizon of the Potsdam sand- 

 stone or in the overlying slates. According to McCreath, they are 

 distinguishable in Pennsylvania as ores at the top, ores in the 

 middle, and ores at the bottom of the great limestone No. II. 

 Those at the top form the belt along the central part of the valley 

 where the Trenton limestone underlies the Utica or Hudson River 

 slates. Those in the middle are connected with various horizons 

 of ferruginous limestones in the Chazy and Calciferous. Those at 

 the bottom along the north or west part of the South Mountain- 

 Blue Ridge range are geologically connected with the Potsdam 

 sandstone, or the slates which intervene between it and the base of 

 the Calciferous. (Second Penn. Survey, Rep. MM, p. 199.) Cobalt 

 has been detected on those of Chester Ridge by Boye, but it is a 

 rare and unique discovery. 2 



ii., XXXII. 355. H. Carvill Lewis, "The Iron Ores of the Brandon Pe- 

 riod," Amer. A. A. Sci., XXIX. 427, 1880. J. F. Lewis, "The Hematite 

 (Brown) Ore Mines, etc., East of the Hudson River," M. E., V. 216. J. G. 

 Percival, Rep. on the Geol. of Conn., p. 132 ; also, Amer. Jour. Sci., ii., 

 11.268. R. A. F. Penrose, "Report on Manganese Ores," Geol. Survey 

 Ark., 1890, Vol. I. (Contains many valuable descriptions of Vermont 

 limonites.) B. T. Putnam, Tenth Census, Vol. XV. C. N. Shepard, "No- 

 tice, etc., of the Iron Works of Salisbury, Conn.," Amer. Jour. Sci., i., 

 XIX-. 311. J. C. Smock, Butt. Vll. New York State Museum, pp. 12, 52. 

 N. H. and H. V. Winchell, " Taconic Ores of Minnesota and Western New 

 England," Amer. Geol., VI. 263. 1890. 



1 B. T. Putnam, Tenth Census, Vol. XX., p. 176. See also Geol. Sur- 

 vey Neiv Jersey, 1880. 



2 Dr. Boye, "Oxyd of Cobalt with the Brown Hematite of Chester 

 Ridge, Penn., Amer. Phil. Soc., January, 1846. P. Fraser, Second Geol. 

 Survey Penn., Reps. C and CC ; "Origin of the Lower Silurian Limonites 



