68 THE ILLINOIS GLACIAL LOBE. 



do not enter rock. East of this ridge, along Sand}* Fork of Pigeon Creek, 

 wells are usually obtained at a depth of 25 feet or less. In some instances 

 they penetrate alternations of blue clay and sand beneath the loess, while 

 in other instances nothing but sand is found. In some of the ravines lead- 

 ing into Sandy Fork, a gray gummy clay carrying a few small pebbles 

 immediately underlies the loess. It appears to be stained with humus, and 

 probably represents the Sangamon interglacial stage. A creek exposure in 

 the southwest part of sec. 23, T. 2 S., R. 10 W., shows a red, weather- 

 stained, sandy gravel below the loess. 



West of the drift ridge along Muddy Fork of Pigeon Creek, wells 

 usually enter blue clay at about 30 feet, and in several instances have been 

 sunk to a depth of about 100 feet without reaching rock. One well 3 miles 

 west of Fort Branch, on the farm of Henry Lehring, struck rock at a depth 

 of 114 feet. Two miles farther west, on more elevated ground, rock is 

 struck at 12 to 20 feet. 



In western Pike County, Indiana, in sees. 13, 23, 24, and 26, T. 1 S., 

 R. 9 W., several roadside exposures of till having a thickness of 5 to 10 feet 

 were found apparently at the extreme limits of glaciation. For several miles 

 east from these sections the thickness of the drift on the uplands seldom 

 exceeds 10 feet, and the loess here is reduced to a thickness of but 5 or 6 

 feet. In a lowland tract along Flat Creek, in eastern Pike County, which 

 lies near the glacial boundary, the drift has a thickness of 75 to 120 feet or 

 more. At the A'illage of Otwell, which stands in this lowland, Dr. W. M. 

 De Motte made a boring which reached a depth of 119 feet without strik- 

 ing rock, though the well mouth is only 485 feet above tide, and scarcely 85 

 feet above the neighboring portion of East White River. A boring made by 

 William Bell near the head waters of Mud Creek and Flat Creek, 6 miles 

 west of Otwell, reached rock at a depth of 78 feet, and several other wells 

 within 2 miles north and east are reported by Mr. Bell to have reached rock 

 at 75 to 80 feet. The drift in this lowland is reported to be largely a blue mud. 

 There is, however, considerable sand just below the loess, exposures of which 

 may be seen along the ravines and at roadsides. This lowland, as indicated 

 on a later page, was apparently the line of discharge for a part of the Patoka 

 drainage basin into White River, which it entered near the junction of the 

 two forks east of Petersburg. On the uplands bordering this lowland on 

 the north and east, rock is usually entered at 35 feet or less, while on the 



