132 PUBLIC PARKS OF IOWA 



Although now no remnant of former mountains remains in the relief 

 expression of the region and the entire area of once high altitudes is as 

 level and as smooth as any other part of the vast interior plain, there 

 persists beneath the glacial mantle, mountain structures as well pro- 

 nounced and as typical as they are anywhere else in the world. The 

 broadly arched strata, the folded formations, the faulted rocks, the 

 intrusions of once molten magmas, the prodigious extravasations of 

 volcanoes, are familiar features which are characteristically developed. 

 The evidences or erogenic uprisings are unmistakable. Seldom to the 

 geologist are mountain phenomena more clearly depicted. Form, extent 

 and stratal attitude are measurable with great precision. 



The discovery of the old and long-buried mountain range is a matter 

 so recent and so instructive that a brief state of the manner of its 

 finding is not without distinct interest. It well illustrates the method 

 of modern scienific venture beyond the confines of the known. By peel- 

 ing off, as it were, the thick Cretacic and glacial coverings of the area 

 the entire Mesozoic floor is laid bare, and the Paleozoic formations then 

 constitute the uninterrupted bedrock of the whole region. By what is 

 essentially the same thing elimination of these later coverings is ac- 

 complished by plotting the numerous deep-well records and other data 

 relating to the underground structures. 



Casually referring to a general geological map of the area, the various 

 Paleozoic terranes are seen to be distributed in relatively narrow belts 

 trending in a northwest direction. Singularly -these belts in southern 

 Minnesota abruptly terminate. The cause has been long perfectly in- 

 explicable. It is now found that the most ancient rocks form the core of a 

 rather notable arch, the axis of which is directed northeastwardly. It 

 is a true anticline structure of large proportions and great longitudinal 

 extent. After the country had been bowed up it was planed off quite to 

 sea level. It is against this anticline that the belted Paleozoics are up- 

 turned and cut off. Indeed, they too once extended unbrokenly over 

 the old arch. In northern Minnesota and in Manitoba the same belted 

 formations abruptly appear again. The discovery is a result of inductive 

 reasoning that is quite remarkable. The whole problem was, in fact, 

 fully worked out before its proofs were even sought in the field. Lines 

 of reasoning and results of extensive observation are in strict accord. 

 Discovery was made before the facts themselves were even presented. 



Rarely in so small a compass is there so well displayed the effects of 

 every great geologic process known. For countless ages fire, flood and 

 frost have played upon these rocks without completely effacing them. 

 Volcanic outbursts have seamed, seared and smelted these formations 

 until often they are almost beyond recognition, but they are not yet 

 destroyed. When rains have failed to wash these rocks away or the 

 rivers have been unable to wear them down, the sea has time and 

 again cut into them or carried them hundreds of fathoms deep, yet they 

 have reared themselves again above the surface of the engulfing waters. 

 Heat and sun and chill of ice have alternately contended in flaking off 

 the rock surface, still they have ever presented new faces to these in- 

 sidious attempts at their destruction. Winter blasts and the siroccan 



