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AMERICAN GEOLOGY. 
4. The iron mountains of lake Superior are equally as rich 
as northern New York. There are some, perhaps, who may 
regard this comparison as unjust to lake Superior; but it must 
not be forgotten that one mine, the Sandford Lake mine, is be¬ 
tween six and seven hundred feet thick. A square yard of ore 
weighs four tons. 
5. Maryland, Virginia and North Carolina possess inexhaust¬ 
ible supplies of iron ore, which are mostly the hydrous perox¬ 
ides of iron. The hematites of Vermont, eastern New York, 
are very extensive. 
6. The brown ores of iron in the south-western counties of 
North Carolina, and in eastern Tennessee, are immense. 
A mineral so important as iron should be widely distributed, 
and it appears that in the United States, every important sec¬ 
tion is supplied with it. The largest section or formations 
which are destitute of the ores of iron and of the metals, are 
the Cretaceous and Tertiary, which skirt the Atlantic coast and 
which form our great basins and valleys. So also, the Silurian 
and Devonian systems are in a great measure destitute of iron 
ores, with the exception of the argillaceous and oolitic ores of 
iron of the Clinfbn group. 
7. I have already spoken of the value ol the lead ores of 
Wisconsin, Missouri and Iowa. The highest estimate which I 
have noticed of the probable productive capacities of the lead 
region, is from one hundred to one hundred and fifty millions of 
pounds annually, having already reached that of fifty millions 
under unfavorable circumstances. 
8. The production of copper is in its infancy. It is too early 
to attempt to determine the value of its mines, and yet the lake 
Superior copper district has already produced two thousand tons 
in a single year. The value of the copper which has been 
produced equals, at twenty-five cents per pound, $2,700,000. 
The copper region which ranks next in value is in North Caro¬ 
lina. It has been referred to. The ore is the yellow sulphu- 
ret; the country is far better adapted to mining than that of 
lake Superior. Indeed, it is of all others the best, whether we 
