113 



the "Knobs," coiupromisiiii; tin- counties of Flnyd, eastern Washington, 

 Jackson and Brown, and lapping over into eastern Lawrence ami Monroe, 

 is a region of mature topography, with deep, steep-sided valleys, very little 

 level njiland, and broad flat valleys only on the larger streams. To the 

 west of this lies the great limestone region (Mississippian limestones) in 

 Harrison, western Washington and eastern Orange, central Lawrence and 

 Monroe, and northeastern Ow-en counties. The topography of this region 

 ii-, rolling, with deeper valleys on the eastern and western edges only, it 

 is the region of caves and sinkholes, and consequently, to a marked de- 

 gree, of underground drainage'. It is also the region of chief interest 

 in the present connection. 



To the west of tlie limestone belt lies the region of the Chester 

 (Huron) formation and the Mansfield sandstone, which for our present 

 imrposes may be treated as a unit. Toitographically this region bears con- 

 sideralile resembl.-inco to the region of the "Knobs." In places it is 

 even more rugged, as in Martin and Craw^ford counties. One important 

 point of difference, however, from the standpoint of the water-supply engi- 

 neer, is the fact that in this region of the Chester formation, the larger 

 streams cut through the shales and sandstones to the limestone beneath, 

 while in the region of the "Knobs," the valley floors are always in the 

 same material as their sides. This type of valley in the Chester region 

 is well exemplified liy Richland Creek, in Monroe and Greene counties, 

 and by French Lick Creek in Orange County. 



To the west still of the region of the Chester and Mansfield forma- 

 tions, is the region of the Coal Measures, which presents no points of 

 special interest to the present discussion. 



Broadly speaking, we may say that the driftless area presents, from 

 the standpoilit of the water-supply engineer, two main types of geo- 



1 For descriptions of the geology, topography and caves of this region see : 

 Blatchley, W. 8.. Indiana Caves and their fauna, 21st Ann. Rept. Indiana Dept. 

 Geol. and Nat. Res., 1897, pp. 120-212 ; Hopkins, T. C, and Sicbenthal, C. E., 

 The Bedford Oolitic limestone of Indiana, Hid., pp. 289-427 ; Neivsom, J. F., A geo- 

 logic and topograpliic section acros.s southern Indiana, Ibid., 26th Ann. Rept., 1901, 

 pp. 227-.'502 : Ashley. G. H., and Kindle, E. M., The geology of the Lower Car- 

 boniferous area. Ibid., 27th Ann. Rept., 1902, pp. 49-122 ; Shannon. G. W. and 

 others. The Indiana Soil Survey, in the 32d to 34th Ann. Repts., Ibid., 1907-10; 

 Cinninys, E. R., On the weathering of the Subcarboniforous limestones of southern 

 Indiana, Proe. Ind. Acad. Sci. for 1905, pp. 85-100 ; Greene, F. C, Caves and cave 

 formations of the Mitchell limestones, Ibid., for 1908, pp. 175-183 ; Beedc, J. W.. 

 The cycle of subterranean drainage as illustrated in the Bloomington, Indiana, 

 quadrangle. Ibid., for 1910. pp. 81-111. 



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