THE PENOKEE IRON RANGE. 
395 
On the north side the slope of the range is moderate, and 
covered with u Drift;” but on the south it is quite abrupt, and 
steep, rocky precipices occur, looking as if they had at some 
remote period of the past, formed the shores of some great 
body of water. 
What gives this great ridge its peculiar interest and import¬ 
ance, is the immense stratum or bed of magnetic iron ore which it 
contains, extending, with varying thickness and value, through* 
out its whole length. It is not therefore an Iron Mountain 
simply, like those heretofore known in Missouri and elsewhere ; 
but, as its name imports an Iron Range ; as if mountain masses 
of iron had been passed between gigantic rollers, and drawn 
out for a length of twenty miles. The ore is found in a very 
ancient chloritic state, so ancient that it is supposed to have 
been deposited long before the existence of vegetable or animal 
life upon the globe. The slate rests upon a light coloied 
quartz-rock, which usually extends to the base of the Range on 
the south side. The ore is laminated like the slate and appa¬ 
rently has had the same origin ; for as we ascend from the 
quartz-rock, the slate becomes more and more ferruginous until 
it passes into pure iron ore. This change is so gradual that it 
is often difficult to determine where the slate ceases and the ore 
begins; or how much should be classed as iron ore and how 
much as ferruginous slate. We noticed places where the ore 
had a thickness of sixty feet; at other places ten ; and where- 
ever we could get access to the rock at the proper place, the 
ore was found. 
Above the ore, that is north of it, the slate has been har¬ 
dened, probably by some volcanic agency, into a compact mass, 
but still showing traces of its original laminated structure. 
This highly indurated rock is the nucleus of the ridge, usually 
forming the crest or highest part; and it forms the north slope, 
except where covered with the boulders and other coarse mate¬ 
rials of the Drift formation. If we may judge from the pol¬ 
ished and’grooved surfaces, we may suppose that this excessvely 
hard rock has resisted the action of the powerful currents and 
