CENTURY OF IOWA GEOLOGY 411 



peiiods discovered in a then remote part of our continent years 

 before it is recognized in the East. 



PRIMARY GEOLOGICAL CROSS-SECTION OF MISSISSIPPI VALLEY 



Iowa was still primeval wilderness when first attempts were made 

 to decipher the geological substructure of her broad prairies. In 

 those early days the construction of a geologic cross-section from 

 verge to verge of the vast Mississippi valley was an undertaking of 

 no mean proportions. Following closely in the Wernerian foot- 

 steps of William McClure, father of American geology, Dr. Edwin 

 James, who was surgeon, botanist, and mineralogist of the famous 

 Long Exploratory Expedition to the Rocky Mountains, in 1819-20,® 

 endeavored to extend McClure's section of the forty-first parallel, 

 from the Alleghany Mountains to the Rocky Mountains. 



Crude as the results appear at this day the simplicity of structure 

 largely obviates serious error that otherwise might have been made. 

 This parallel of latitude crosses the southern part of our state. 

 Although Doctor James afterwards lived in Iowa, near Burlington, 

 for more than a quarter of a century, at the time of the Long trip 

 he traversed only the southwestern corner of the state. A similar 

 cross-section was executed along the thirty-fifth parallel, which was 

 intended to be a continuation of McClure's "Fifth" section. 



In spite of his strong Wernerian predilections an important ob- 

 servation was the recognition of the coal formation. He made the 

 prediction that some day these coal deposits would prove to be of 

 very great value. 



The striking feature brought out in the cross-section was the fact 

 that throughout the breadth of the Mississippi basin the strata re- 

 posed practically undisturbed. This condition contrasted strongly 

 with the tilted beds at either side. Thus was early although faintly 

 adumbrated that basin-shaped form of the continent of which in 

 later years Dana made so much. 



As a matter of fact James' work was really one of the larger 

 undertakings in the geological field of his day. 



TERRANAL CORRELATION OF ORE DEPOSITS 



Although erroneous in principle early application of the idea that 

 mineral deposits are in some way genetically connected with specific 

 geological formations under certain limitations proved to be unex- 

 pectedly fruitful in ore exploration. Its first presentation was a 



^Account Exped. Pittsburg to Rocky Mts., in 1819-20, Vol. I. Philadelphia, 

 1823. 



