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Indiana University Studies 



positively called local peneplains, such as should have resulted 

 had the amount of uplift been less than the difference between 

 the Kirksville level and the present grade level. Certain 

 broad benches do occur, but in every case they may be cor- 

 related with the particular strata upon which they are 

 developed, since they are consistently present upon certain 

 strata, and have their elevations corresponding exactly to the 

 dip of the strata. Another criterion of local peneplanation 

 which may be looked for is the presence of sags in the inner- 

 stream ridges, developed at a fairly consistent level. One 

 such is found at Ridgeport at an elevation of 735 feet, near 

 the base of the Mansfield sandstone; another northeast of 

 Koleen at an elevation of 705 feet, near the base of the Mans- 

 field and in shale; a third at Tanner at an elevation of 735 

 feet; and a fourth, one-half mile southwest of Tanner at an 

 elevation of 740 feet. These two latter are developed on the 

 Cypress sandstone, and reallj' mark the beginning of the more 

 or less continuous line of benches above the ''American Bot- 

 toms" valley developed on the same strata. Briefly, it may 

 be said that these sags constitute the sum total of the evidence 

 that local peneplanation above the present stream level and 

 below the Kirksville level has taken place in the region, and 

 that there is insufficient evidence upon which to base a claim 

 of local peneplanation below the Kirksville level. 



In other portions of the driftless area, conspicuous local 

 peneplains are found below the level of the more ancient 

 Kirksville plain. Beede'- has identified a wide-spread pene- 

 plain developed on the Mitchell limestone to the east of the 

 ''American Bottoms" region. This peneplain he named the 

 Mitchell plain from its excellent development at Mitchell, 

 Ind., on the Mitchell limestone of southern Lawrence County. 

 It has an elevation varying from 100 to 175 feet below the 

 Kirksville plain where both are present in the sam.e region. 

 Judged from its development exclusively on the Mitchell lime- 

 stone it does not satisfy all the tests of a genuine peneplain. 

 It has a fairly uniform inclination accordant with the dip of 

 the limestone upon which it is developed. The writer has 

 proved this by making several sections across it. In Harrison 

 and Washington counties it seems to have been developed 

 about the horizon of the top of the St. Louis limestone near 



" Loc. cit., p. 26. 



