444 THE GEOLOGY OF MINNESOTA. 



[Modified drift. 



Pleasant Mound. F. O. Marks; S. E. }, sec. 25: well, 55 feet; soil, 2; gravel, 6; light-gray 

 " hardpan," very hard, 18; blue till, soft and moist, 29; water rose thirty-five feet in a few hours 

 from a dark mud at the bottom. 



William Robinson; sec. 26: well, 64: soil, 2; yellow till, spaded, 18; sand and gravel, 1 foot; 

 soft and moist blue till, 43; with quicksand at the bottom, from which water rose thirty feet in 

 six hours. 



Ceresco. L. A. Pratt; sec. 24: well, 48; soil, 3; yellow till, spaded, 15; softer and moister 

 blue till, 28; sand and gravel, 2 feet, reaching deeper; water rose four feet from this sand. Small 

 fragments of lignite occur frequently in the wells of this region. 



Lincoln. W. G. Bundy; sec. 30: well, 30 feet; soil, 2; yellow till, spaded, 24; harder blue 

 till, 4 feet, and reaching deeper; water comes in sandy and gravelly veins in this blue till, becom- 

 ing four or five feet deep. 



Butternut Valley. Thomas Wilson; sec. 28: well, 58 feet; soil, 3; yellow till, spaded, 15; 

 blue till, soft and moist for the first five feet, then mostly very hard and compact, requiring to 

 be picked, in all, 40 feet, containing a piece of lignite, nearly a cubic foot in size, at a depth of 

 about thirty feet from the surface; no sand nor gravel, and no good supply of water; this well has 

 therefore been filled up. 



Martin Osten; sec. 21: well, 28 feet; soil, 2; yellow and blue till, 26; with gravel and sand at 

 the bottom, from which water rose to six feet below the surface. 



Cambria. David T. Davis; sec. 26: well, 40; soil, 2; yellow till, spaded, 18 feet, containing 

 gravelly streaks in its lower part, with a little water; much harder blue till, picked, 20; enclosing a 

 vein of gravel and sand at the bottom, from which water rose two feet. 



William E. Jenkins; sec. 34: well, 24 feet ; soil, 2; yellow till, 18 ; harder blue till, 4 feet 

 and extending lower; water seeps. Several small pieces of lignite were found in each of these 

 wells. 



Modified drift. In addition to the beds of modified drift enclosed in the 

 till or lying below it, other accumulations of this kind of drift, derived di- 

 rectly from the ice-sheet but deposited by water, occur on the surface of 

 areas which are mainly till. They consist of interstratified gravel and 

 sand in knolls or mounds that rise ten to twenty feet, and rarely fifty to 

 seventy-five feet, above the general level. These are seldom very numer- 

 ous in western Minnesota, and are rarely extended in ridges or in any 

 notable series. Their origin, however, was probably similar to that of the 

 gravel ridges or kames which often form long series in other drift regions, 

 being the deposits formed between walls of ice by glacial rivers that were 

 poured down from the surface of the melting ice-fields. The only notable 

 accumulations of this class in Blue Earth county are the group of hillocks 

 before described in section 25, Pleasant Mound, and occasional knolls of 

 fine gravel arid sand, ten to fifteen feet in hight, in Butternut Valley and 

 Cambria townships. 



The valley of the Minnesota river at the north side of the county has 

 been filled with modified drift to a depth ol about one hundred and fifty 

 feet, but it has since been nearly all excavated and carried away by the 

 river. 



