CORRELATIVES OF BLOOMINGTON MORAINIC SYSTEM. 113 



be ascribed to tbe wind. But there is almost no sand on the bordering districts and little if 

 any evidence of lake occupancy of the region after the retreat, of the ice. The origin of 

 the ridge, therefore, remains uncertain. Very few points within several miles are higher than 

 the ridge, which stands on a prominent part of the upland 700 feet or more above sea level. 



Another undulatory strip li miles wide, carrying basins as well as low swells, follows Fall 

 Creek from Middletown to Pendleton in Madison County, but does not appear to extend west 

 of Pendleton. 



Another gently undulating strip about a mile wide follows the north side of White River 

 from Anderson westward to the Hamilton County line, where it crosses to the south side of the 

 valley and continues between White Eiver and Stony Creek, apparently terminating at the 

 bend of White River north of Noblesville. Bowlders are somewhat more numerous on it 

 than on border plains, but few of the swells exceed 10 feet in height, and no connection was 

 established between it and any well-defined moraine. 



Along North Wildcat Creek from Burlington to Cutler and south from there to the vicinity 

 of Sedalia in northern Clinton County there is an isolated belt of a dozen or more square miles 

 in which knolls 20 to 40 feet high occur. 



Along the east bluff of the Wabash in Carroll County a belt a mile or more in width dis- 

 plays a tendency to ridging parallel with the river. The most prominent ridges He west of 

 Rockfield in sees. 1 and 2, T. 25 N., and sec. 36, T. 26 N., R. 2 W.; they stand 20 to 30 feet 

 above the low ground between them and slightly less above the plain to the southeast. About 

 3 miles northeast of Delphi, near the corners of sees. 14, 15, 22, and 23, a group of gravel knolls 

 rise rather sharply 12 to 15 feet above interspersed basins. Together they cover less than a 

 square mile. All around them the surface is very gently undulating. 



What is perhaps the best-defined and longest undulating strip in the district consists of 

 scattered knolls distributed over a strip 1 to 5 miles in width, leading from Muncie northwest- 

 ward to Peru. Its south border in western Delaware County leads westward near the line of 

 the Lake Erie & Western Railroad into Alexandria. After crossing a swampy channel west of 

 Alexandria it turns northwestward and leads past Rigdon and Point Isabel into Howard 

 County, where for a few miles it forms the divide between Wildcat Creek and the headwaters 

 of Pipe and Deer creeks. It runs into Miami County between the north and south forks of 

 Deer Creek past the village of Wawpecong, comes to North Deer Creek at Miami village, and 

 thence rims north to Pipe Creek and Bunker Hill. It then follows Pipe Creek valley north- 

 westward to the Wabash at the line of Miami and Cass counties about 5 miles west of Peru. 

 Few places in this strip bear knolls exceeding 15 feet in height, and less than one-fourth of 

 the surface is more undulatory than the bordering plains. Only in Miami County do bowlders 

 abound and they are about as numerous west of the undulatory strip as they are along it. 



STRUCTURE OF THE INNER BORDER. 

 COMPOSITION. 



General features. — Till constitutes the greater part and especially the surface portion of 

 the drift of the intermoramic tract or inner border. What little gravel there is on the uplands 

 is in the sharp knolls or in small patches in the till plain, there being no extensive gravel plains. 

 Along the valleys of the principal streams considerable gravel and some gravel knolls and 

 ridges occur. There is also, as indicated above, gravel in the Anderson esker and in the aban- 

 doned channel in which the esker lies. 



Wells in Boone, Clinton, and Madison counties (see p. 99) pass at depths ranging from 15 

 to 60 feet through a black mucky soil which may indicate the top of the deposit at the pre- 

 ceding ice invasion. A soil is struck in some localities at exceptional depth — for example, at 

 103 feet in the "Brobst" gas well in southeastern Howard County. 



Of many well sections and estimates of drift thickness collected, the following have been 

 selected : 



