APPENDIX—GEOLOGICAL SURVEY. 
447 
ness of the strata of the lead district have been removed by de¬ 
nudation. Let us take our stand for a short time on the origi¬ 
nal surface of the lead district, say 350 feet above the present 
surface, near which a large portion of the ore in the lead dis¬ 
trict has been found. We are now separated from the upper 
magnesian limestone by at least 200 feet of what is called the 
Hudson river group, and the Niagara limestone. 
Then nothing more could be known of the upper magnesian 
limestone from the original surface of the lead district, than 
can be known now of the lower magnesian from the present 
surface. The upper magnesian was then, as the lower is now, 
hid beneath two or three hundred feet of a different class of 
rock. Suppose, however, that the examinations were made at 
that time beyond the limits of the present lead district, where 
the upper magnesian would become the surface rock, that is, 
where it could be seen without any excavations being made, 
and finding it barren, as we know it is to-day where it can be 
seen, it was pronounced to be barren rock, and from what was 
seen of it there, it was pronounced to be barren rock every¬ 
where else in the state. That is to say, because productive 
mineral veins or ore deposits were not found on the surface, 
where the rock might be seen, it must therefore of necessity 
be a barren rock. What would we think of the judgment of 
such parties to day, when denudation has removed the overly¬ 
ing strata and brought to our view in the upper magnesian ore 
deposits at which the world has been astonished ? And yet 
these are the very views and evidences by which the lower 
magnesian is now condemned, and for no better reasons than 
those assigned above. There is not a place in the lead district 
where the lower magnesian is seen, or can be seen‘(without 
deep mining) in connection with the physical conditions that 
have rendered the upper magnesian so productive. And to 
say it is a barren rock beneath the mines of the lead district, 
from what we can see of it out of the lead district , is the height 
of folly. Such views are unworthy either of practical or sci¬ 
entific men. 
