PENEPLAINS OP DRIFTLESS AREA L27 



Shipton. W. D.. The Geology of the Sparta Quadrangle, Wisconsin: 



Master's Thesis State Univ. of Iowa, unpublished. 

 Trowbridge, A. C, Some Partly Dissected Plains in Jo Daviess County, 



Illinois: Jour. Geology, Vol. XXI, pp. 731-742. 

 Preliminary Report on Geological Work in Northeastern Iowa : Proc. 



Iowa Acad. Sci., Vol. XXI, pp. 205-209. 

 Physiographic Studies in the Driftless Area (abstract) : Bull. Geol. 



Soc. America, Vol. 26, p. 76. 

 Trowbridge. A. C. and Shaw, E. W., Geology and Geography of the 



Galena and Elizabeth Quadrangles: Bull. No. 26, Illinois Geol. 



Survey, pp. 136-146. 

 Williams, A. J.. Physiographic Studies in and around Dubuque, Iowa: 



Master's Thesis State Univ. of Iowa, unpublished. 



Grant and Burchard describe one undoubted peneplain at 

 1.320 to 1,000 feet altitude which they call the Lancaster Pene 

 plain, and mention a probable higher peneplain at about 1,420 

 feet. In the Galena-Elizabeth quadrangles, Illinois, Trow'oridge 

 found two peneplains, the Niagara plain at 1,170 to 1,100 feet, 

 and a lower plain, the Galena plain at 975 to 900 feet. Like- 

 wise, field work by A. J. Williams and others under the direction 

 of Professor Trowbridge in northeastern Iowa has established 

 two peneplains. During the past summer W. D. Shipton found 

 a peneplain and a probable lower one in the Sparta district of 

 Wisconsin. Work by the writer in the Richland Center quad- 

 rangle, Wisconsin, seems to have established plains at two dis- 

 tinct levels. But all the work has not been so nearly harmonious, 

 for Salisbury and Atwood have suggested the possibility of four 

 peneplains in the Baraboo district and Hershey has given the 

 number as five for the entire Driftless Area. 



On account of the wide distribution of the areas studied it has 

 not until now been possible to study the peneplains continuously 

 over wide areas. At the present time, however, sufficient data 

 are in hand to make possible the correlation of an area extend 

 ing from Baraboo, Wisconsin, to Waukon and Dubuque, Iowa. 

 and to the southern part of the Elizabeth quadrangle in, Illinois. 



STRUCTURE OF THE ROCKS. 



The structure of the stratified rocks of the area is simple, with 

 two exceptions. In general the strata form a gently-dipping 

 monocline, in which the dip is about fifteen feet per mile in a 

 southwest direction. But the quartzite formation at Baraboo is 

 closely and intricately folded, and the Paleozoic strata in the 



