Mesozoic and Cenozotc Geology and Paleontology. 225 
in the valley of the south branch of Root river, in this county, known 
as the “Hagle Rocks.’’ The valley is cne of denudation, by the ordi- 
nary suberial forces, and it has been excavated out of the Trenton 
Group; and yet, two lone towers, rising as high as the rocky walls of 
the valley, are standing to say that no glacial sheet ever moved in this 
valley. 7 
_ Indeed, no one having any knowledge of geology, has found any evi- 
dence of glacial action in the Mississippi valley, or in the streams that 
flow into it from Minresota; but, on the contrary, every geological fact 
bearing upon the subject is so strongly against it, that we unhesita- 
tingly conclude that no glacier, great or small, ever entered it; and as 
to the hypothetical continental glacial sheet in this valley, it certainly 
suggests physical impossibilities. The valley of the Mississippi is 
one of erosion. At Minisca, the hills are 525 feet high. ‘The slopes 
are such as are made by ordinary forces, without the intervention of 
anything extraordinary. The harder layers of rock stand out in bold 
cliffs on the sides of the valley, while the softer layers form slopes be- 
tween the harder layers, marking the disintegration and denudation as 
it takes place under atmospheric influences, Streams enter the valley 
at right angles, and these are fed by streams flowing into them from 
the north and from the south in valleys of corresponding depth, and 
__ protected by sides of similar slopes and cliffs, and even more rugged 
bluffs; for, as we recede westerly from the Mississippi river in South- 
ern Minnesota, higher rocks come into view, until the valleys are exca- 
vated in the limestones of the Trenton Group, instead of the softer 
magnesian limestones that abut upon the Mississippi valley. If a 
sheet of ice were to fill these valleys above the top of the dividing 
ridges, we may fairly conclude that it would be held so firmly that it 
could move in no direction; but if it could move either north or south, 
or east or west, the sharp escarpments of magnesian limestone, the 
rugged bluffs of the Trenton limestone, the bold outliers in the widened 
valleys, and the pinnacled towers on the level prairies forming the 
divides between the streams, would be ground down, smoothed off, or 
entirely torn away. 
A trip up the Mississippi river, from Dubuque, Iowa, to St. Paul, 
Minnesota, or across the country at La Crosse, Minisca, or Lake 
Pepin, will bring to the view of the observer the incontestible evi- 
dences against the existence of a continental glacier, in times so 
recent as the Pliocene or Post-pliocene. In the absence of the 
opportunity of taking the trip, turn to Owen’s Geological Survey 
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