434 
WISCONSIN STATE AGRICULTURAL SOCIETY. 
What is true of the azoic formation at Lake Superior, is 
true of it the world over. During the deposition of these 
strata, the interior of the earth was not only the source of con¬ 
stant emanations of iron, but also of all the other metals. It 
was a period in nebular condensation when the crust of the 
earth had become too thick and dense to conduct its radiant 
heat into surrounding space, hence it was thrown into those 
lines of fracture peculiar to these strata, which were then the 
safety valves of a cooling world. Who among us that knows 
anything about mines or mineral strata but is aware of the fact 
that the lower silurian rocks are the mineral strata of the world. 
And why ? Because its lower members are formed over the 
azoic rocks, and over their lines of fracture, and consequently 
must have received these metallic emanations, a large portion 
of which must have been thrown down by chemical deposition 
in their passage through the fissures of these rocks. 
If these deposits of iron were found in rocks whose geologi¬ 
cal position was thousands of feet above the azoic, a man might 
be pardoned for looking for their origin in physical conditions 
or forces acting from above. But here in the lowest member 
of the Silurian series, within a few feet of the azoic rocks, and 
with the impress of their lines of fracture on the rocks before 
us, it is folly in the extreme to look for any other origin. I 
would ask pardon myself for dwelling so long on this subject, 
but for one thing, and that is the relations of these deposits to 
the deposits ot lead and zinc in the lead district are so clearly 
defined as to make their common origin certain. It is in fact 
a continuation of the same ore district with iron ore predomi¬ 
nating. 
The outcroppings of these deposits of iron ore I have traced 
along a belt of land 55 miles long, east and west, and from 
four to six miles wide ; consequently it will add nearty three 
hundred square miles to the ore district of southern Wisconsin. 
Since attention was first called to this discovery in July last 
a company has been formed to manufacture these ochres at 
Blue River, their factory being now in working order; and 
they have, I understand, several hundred tons of this material 
