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IOWA ACADEMY OF SCIENCE 



southern part of the Elizabeth quadrangle have much steeper . 



- :han the average for the Driftless Area. The seemingly 

 simple monoelinal structure is further complicated by numerous 

 gentle anticlines and shallow synclines. much jointing, and slight 

 faulting. 



THE UPPER PLAIN. 



plains, the upper and older one will be discuss 

 Reference to figure 11 shows that over the whole region 

 there is much flat land which stands distinctly above the level 



-: zats and which forms remnants of a now much 

 plain. In drawing conclusion- r.ing the origin and corre- 



.- of this plain, several points si -red. 



1 re monadnocks standing above it, which are ero- 



sional remnants of a once still higher surf a - is well illus- 



1 in the Baraboo region where Sauk Point at 1.620 feet, 

 above sea level and the west blur lis Lake at 1,560 



stand above the plain whose altitude here is 1,400 feet. The 

 same relation is found at Waukon. Iowa, where a monadnoek 

 ses at least ] the uppermost plain. Also Platte 



Mounds and Blue Mounds may be considered to be monadnocks 



- ling upon the upper plain. 



_ At many points throughout the southern portion of the 



& Area, patches of water- worn gravel are found on the 



r plain. On the west bluff of Devils Lake several fe< - 



I ae gravels are found on an old erosional surface and 



here eloa - -iated with numerous potholes. These 



same gravels are found near Sparta. Wisconsin, at an elevation 



of 1 - known at Seneca. "Wisconsin, and at 



"Waukon. Iowa ; they occur at 1300 feet altitude. This deposit 



■ .ether with the remnants of higher land above the 



plain points to the previous es of a surface which was in 



an imperfect state of peneplaination. -with moderate relief, and 



reams had sufficient graeL - I :arry gravel such as is 



;d. 



- plain is not parallel with the underlying strata but 



cuts across the bevelled edges of dipping formations, rising strati- 



graphically to the south. - n in figure 11. About Devils 



and adjacent districts to the west,, there are conspicuous 



levels at 1400 feet, which cut across the hard Baraboo quartzite. 



.-. dips at angles of 15' and more. If a line is drawn ''the 



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