1893. | NEW YORK ACADEMY OF SCIENCES. 83 
necessary data are afforded for the interpretation to a certain 
degree of the geological relations. The foundations for this 
interpretation may be briefly summed up as follows, and in the 
summary the reliability of the several statements is indicated. 
1. The ore is interbedded in the limestone. 
2. The deposit is a continuous and single bed (or vein) which 
is bent intoa fold. (This statement rests on the authority of 
the report for 1868, and is corroborated by the mining opera- 
tions and such observations as can be made to-day.) 
Fie. 3, STEREOGRAM OF THE OGDENSBURGH ORE-Bopy. 
3. The wall rock is widely impregnated at the bend with 
franklinite and other minerals, and is pierced by intrusions of 
rather basic syenite. 
4. The ends of the bed and the axis of the fold pitch to the 
north at an angle of about 65°, as recorded in the report for 
1868. The old mines where this might be verified are aban- 
doned. 
- 5. There is a somewhat variable dip to the ore of from 65° to 
45° southeast, but mostly the former. 
Picturing to ourselves the limestones as once flat, they have 
been folded by pressure operating in a northwest and southeast 
