92 IOWA STUDIES IN NATURAL HISTORY 



mit levels, careful inspection brings out distinct differences 

 in altitude between the two plains. For instance, the Lan- 

 caster plain around Lancaster, seems, on casual observa- 

 tion, to grade into the Dodgeville plain on the summit of 



Fig. 23. View east of Waukon, Iowa, showing both the Dodgeville and Lancaster 

 plains. The picture was taken from the Dodgeville plain which shows in the fore- 

 ground and forms the skyline. The general topogi'aphy which forms the rims of the 

 valleys in the middle distance is the Lancaster plain. 



Military Ridge. Grant and Burchard^ included Military 

 Ridge and the area around Dodgeville with the Lancaster 

 plain. However, there are many views obtainable in which 

 Military Ridge stands distinctly above the intermediate 

 levels and carefully drawn profiles show the two plains to 

 be distinct- (Fig. 24). (3) Where both plains are repre- 

 sented in the same locality, they lie at difi'erent strati- 

 graphic horizons, either within the same formation or in 

 different formations, although in practically all cases both 

 lie on resistant rock. (4) If the Lancaster plain be project- 

 ed from districts v/here the Dodgeville plain is missing into 

 areas where the Dodgeville plain occurs it is found to lie 

 distinctly below the Dodgeville plain. . Similarly the Dodge- 



1. Grant, U. S. and Burchard, E. F., Lancaster-Mineral Point Folio, U. S. Gcol. 

 Surv., p. 2. 



2. Hughes, U. B., Proc. la. Acad. Sci., Vol. 23, p. 131. 



