Mesozoic and Coenozoic Geology and Palceontology. 329 



in the vallej' of the south branch of Root river, in this county, known 

 as the "Eagle Rocks." The valle}' is one of denudation, b}- the ordi- 

 narj' suba^rial forces, and it has been excavated out of the Trenton 

 Group; and 3'et, 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 

 valle}'. 



Indeed, no one having any knowledge of geology, has found an}^ evi- 

 dence of glacial action in the Mississippi valley, or in the streams that 

 flow into it from Minnesota; 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 phj'sical 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 

 an^'thing extraordinar}-. The harder layers of rock stand out in bold 

 cliff's on the sides of the valley-, while the softer laj^ers form slopes be- 

 tween the harder la^'ers, marking the disintegration and denudation as 

 it takes place under atmospheric influences. Streams enter the valle}^ 

 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 firml}^ 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 3Iississippi river, from Dubuque, Iowa, to St. Paul, 

 Minnesota, or across the countr}' 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 



