BLUE EARTH COUNTY. 423 



Deep well at Mankato.] 



points in the section, and the other by the city council, representing twenty-nine depths. The 

 second of these series of drillings was divided and supplied a complete duplicate set, which has 

 been placed in the state museum. Descriptive notes were also taken of Mr. Ilodapp's series, and 

 the information gained from both is presented in the following table. Mr. G. C. Hurt states that 

 the thickness of the drift here was 290 feet, consisting mainly of the ordinary boulder-clay or till, 

 excepting occasional layers of sand, varying from a few inches to five feet in thickness. He de- 

 scribes the first stratum of rock, reached at 290 feet, as a hard limestone, of light gray color. 



Drillings from the deep well at Mankato. 



At 310 feet, calcareous clay or shale, of greenish color. 



At 330 feet, dolomite (magnesian limestone), reddish gray, somewhat siliceous. 



At 380 feet, siliceous, reddish gray dolomite, containing green-sand. 



At 390 feet, sandstone, with calcareous and greenish cement; containing much green-sand; 

 the pulverized portions appearing like green shale. 



At 450 feet, pinkish, somewhat siliceous dolomite. 



At 453 feet, dull red quartzyte, or firmly cemented sandstone, finely granular, containing 

 minute specks of green-sand. 



At 495 feet, white, friable sandstone. 



At 560 feet, fine shale, of dull pinkish color; not arenaceous, but the specimen of drillings 

 includes intermixed sand, probably derived from a higher part of the well. 



At 600 feet, like the last. 



At 640 feet, yellowish, iron-rusted sandstone, with rounded, mainly siliceous grains; also 

 including angular particles of dark red quartzyte, or hard, firmly cemented sandstone, similar to 

 that at 453. Some of the quartz grains are covered with a thick scale, which on the outside is 

 iridescent or sometimes black. These coated grains are occasionally aggregated into little lumps 

 which seem to be the same with the dark red particles mentioned. 



At 645 feet, similar to the last, but with less of the hard, dark red sandstone, and fewer 

 coated grains. 



At 650 feet, fine-grained sandstone. 



At 660 feet, yellowish sand rock, consisting of white and yellowish siliceous grains, all rounded; 

 and also containing occasional particles of red grit, and of greenish white, kaolin- like matter. 



At 800 feet, coarse-grained, light gray sandstone. 



At 850 feet, light gray sandstone, like the last, but less coarse. 



At 915 feet, shale, slightly gritty, ocher-like, of dark, dull red color. 



At 1010 feet, sandstone, composed mainly of grains of quartz, partly white, and partly 

 stained with the dull red color of the last. 



At 1060 feet, iron-rusted, somewhat pinkish, shaly sandstone. 



At 1100, 1110, 1130, and 1140 feet, light red, medium-grained sandstone, consisting mostly 

 of particles of white quartz, which are more or less covered with pinkish shale. 



At 1150 feet, coarse gray sandstone, with mostly angular grains. 



At 1240 feet, white sandstone, medium-grained, slightly red-stained. 



At 1265 feet, fine, light pinkish sandstone. 



At 1270 feet, coarser sandstone, reddish gray. 



At 1280 feet, sandrock, having the quartz grains covered with films of red shale. 



At 1320 feet, reddish, shaly sandrock. 



At 1327 feet, very fine-grained, soft, pinkish gray sandstone. 



At 1332 feet, sandstone like that at 1150. 



At 1340 and 1342 feet, fine, reddish gray, soft sandstone, partly ochery or iron-rusted. 



At 1450 feet, coarse, somewhat iron-rusted sandstone, made up largely of grains of white 

 quartz, party water-worn, but often angular, of all sizes up to an eighth or sixth of an inch in 

 diameter. 



At 1500 feet, similar to the last. 



At 1600 feet, medium-grained sandstone, reddish, in part ochery and shaly. 



At 1650 feet, fine sandstone, whitish; including red and orange, apparently clayey, grains. 



At 1700 feet, arenaceous, ochery shale, dull red in color. 



At 1720 feet, red shale, without apparent sand-grains. 



