1893. | NEW YORK ACADEMY OF SCIENCES. 81 
eal map on a large seale (8 in. to the mile) that accompanies the N. 
J., Rep., for 1868, the white limestone forms a belt about 5 mile 
across. On its western side it rises in a hill some 260 ft. above 
the river. The ore body appears as a great hook, affording two 
so-called veins (or beds) known as the front vein and the back 
vein, and connected by a bend (see fig. 1). Beginning at the 
north end of the front vein the ore runs 1100 feet S. 30° W.,, 
then curves around for 300 feet and continues parrallel with the 
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Fic. 1. Mar oF THE ORE-BoDy AT OGDENSBURGH. 
For Explanation of Signs, see Fig. 4. 
front vein about 475 feet until it ends. The ore body dips east- 
ward at about 60° near the surface, but in the Passaic Mine, the 
only one accessible to me, it soon flattens to about 45° at 150 
feet in depth, and then at about 250 shows an even steeper dip 
than at the surface (see section D D fig. 2). In the front vein 
the portion near the foot shows a band richer in zincite and 
willemite than that near the roof, but it is hardly enough to 
TRANSACTIONS N. Y. ACAD. Sci. VOL. XIII. Sig. 6, Dec. 18, 1893. 
