WELLS OF SOUTHERN ILLINOIS. 785 



as the Cache, now largely a cypress swamp, leads westward from north- 

 western Massac County across northern Pulaski and then turns south into 

 the Ohio along the line of Alexander and Pulaski counties. From the head 

 of this swamp there is a well-defined connection with the Ohio River in 

 a low plain leading southeast to Metropolis, across the central portion of 

 Massac County. This plain has been built to a level about 70 to 75 feet 

 above the Ohio River, or 20 to 25 feet above the highest present flood 

 stages of the stream. Its freshness of topography is decidedly in contrast 

 with that of the bordering Tertiary formations, in which there has been 

 great erosion. As noted above (p. 528), this channel was probably silted 

 up either at the Illinoian or the Iowan stage of glaciation. 



In addition to the alluvial deposits found in the valleys and lowlands 

 there is a coating of loess found on all except the most rugged portions of 

 the uplands. This loess has a general thickness of about 12 feet on the 

 border of the Ohio and fully twice that amount on the border of the Mis- 

 sissippi, while in the interior portions, as on the glaciated districts to the 

 north, its thickness is only 5 or 6 feet. Whether the loess originally cov- 

 ered the highest and most rugged parts of this ridge is not known. If 

 originally present it has now been largely removed. A more critical study 

 may perhaps develop decisive evidence on this point. 



INDIVIDUAL WELLS. 



On the most rugged portions of the ridge there are very few residents 

 and these depend chiefly upon cistern water. On the lower tract, between 

 the crest of the ridge and the Cache, there is a limestone district in which 

 wells are usually obtained at 40 to 60 feet or less. In the district covered 

 by Tertiary deposits wells are usually found at moderate depth, seldom 

 exceeding 40 feet. The wells on the lowland connecting the Ohio with 

 the Cache near Metropolis have in several instances reached a depth of 

 60 to 75 feet, but in the neighborhood of the Cache they obtain water at 

 much shallower depth, often being but 15 to 20 feet deep. Along the Mis- 

 sissippi Valley the wells are usually driven to a depth of 30 or 40 feet. It 

 is reported that Mr. Bolin Sublette, an early settler in Union County, 

 dug a well near Wolf Lake Station to a depth of about 80 feet, reaching a 

 level at least 50 feet below the low water of the Mississippi River. It is 

 MON xxxvin 50 



