417 



A study of the topography of the Blooniington Quadrangle shows that 

 there are several rather flat-topped, isolated hills and several long, irregu- 

 lar, flat-topped ridges, all of practically the same height. The hills reach- 

 ing the 900-foot contour and forming the southern rim of Flatwoods 

 proper, are examples of the isolated hills. A typical example of the flat- 

 topped ridges is found in the region of Kirksville, where the irregular 

 ridge extends for several miles in a north and south direction. These 

 high, flat-topped hills and ridges are undoubtedly the remnants of a 

 former peneplain, which may be correlated ; but not absolutely beyond 

 doubt, with that at the base of the Cumberland Plateau, and with its con- 

 tinuation southward and westward into Tennessee, thence northward into 

 Kentucky, where it becomes known as the Lexington Plain. This correla- 

 tion makes it of early Tertiary age. (J. W. Beede, Features of Subter- 

 ranean Drainage in the Bloomington Quadrangle. Proceedings of the 

 Indiana Academy of Science 1910. Ditney Folio, Indiana, U. S. Geol. Sur.) 

 Beede has named the peneplain, which these isolated heights represent, 

 the Kirksville peneplain, after the typical development of it at the little 

 village of Kirksville in southwestern Monroe County. Representatives of 

 it occur along the south side of Flatwoods and between the two main 

 branches of Raccoon Creek. Chambers Hill on the north side is also a 

 representative of it. 



Succeeding this peneplanation there was an uplift of the region of 

 about 175 feet. The streams went to work again, cutting deep valleys in 

 the Kirksville peneplain. In time the stream reached base-level, and by 

 lateral erosion and beveling by the minor tributaries, local peneplains were 

 developed. The wide expanse west of Bloomington. which continues 

 southward through Lawrence, Washington and Crawford Counties, is the 

 best and most strikingly preserved area representing this peneplanation. 

 This plain is in the Mitchell limestone, and is well represented at Mitchell, 

 Lawrence County. It had its maximum development in late Tertiary times, 

 and is the Mitchell plain of Beede, being so designated by him. (Fea- 

 tures of Subterranean Drainage in the Bloomington Quadrangle. The 

 Proceedings of the Indiana Academy of Science, 1910.) Flatwoods at 

 this time was peneplaned, the rim of the higher land and the monadnocks 

 being the remnants of the old Kirksville peneplain. Flatwoods is really a 

 portion of the Mitchell plain. The drainage in late Tertiary times was 

 into White River. The main stream was probably in the long axis of the 



27—4966 



