138 Artesian Well Boring in Southeastern Minnesota — Hall. 



5. From 256 to 302 feet. Not the entire thickness of this bed as 

 shown by the other wells in this city, so this is undoubtedly the lower portion. 



6. From 302 to 314 feet. At 302 feet the borings consisted chiefly of 

 _grains of white sand, but mingled with them were numerous light brown 

 chips of dolomite. 



The formation seems to be quite thin at this locality, the drillings from 

 302 to 314 feet being dolomitic, and below that becoming very sandy. The 

 bottom of Shakopee A is estimated to be 320 feet from the surface. 



7. At 323 the drillings were mostly a white sand, which continued 

 very uniformly to 360 feet; the lower portion takes on a yellowish to liglit 

 brown color. 



8. The drillings between 360 and 403 feet show a dolomite which i.s 

 referred to this formation, the Shakopee B. 



9. The Jordan is represented by the white sands, sometimes fine and 

 sometimes coarse, and at the top with some dolomitic chips lying between 

 403 and 558 feet in depth. 



10. Green shales and sands extend down to the depth of 607 feet, 

 [Compare the Mendota and Elevator B wells]. 



11. This formation, the Dresbach sandstone, characterized for its 

 white sands, occupies the depth between 607 and 780 feet; towards the 

 bottom it becomes somewhat green. 



12. As green shales we have this bed reaching down to 844 feet. 



13. Sand again occurs at 844 feet, which has a somewhat greenish 

 color at the top; becomes white and clean at 960 feet and assumes a reddish 

 tint at 1,010 feet. 



14. From 1,010 feet to the last drillings taken from the well the 

 material was a red sand, mingled towards the bottom with a light green 

 shale. At 1,560, 1,850, 1,975, 2,100 feet, there was no perceptible change in the 

 appearance of the drillings; at 2,150 feet a sample was referred to the writer 

 by the superintendent of the cemetery. An examination showed pieces of 

 quartz, hornblende, feldspar, both orthoclase and plagioclase, and some 

 chloritic mineral. As those minerals were evidence of granitic material, 

 the opinion was given that the Pre-Cambrian rocks were reached. The 

 well was sunk no further and the hole was allowed to fill, as no flow of 

 water was secured. 



Total depth of the well, 2,150 feet. 



II. The Washburn C Weli *— A^. H. Winchell. 



Formation 1. From 825 feet above the sea, the first 10 feet down- 

 wards is made up of soil and glacial drift material. 

 2 and 3. Not represented. 



4. Twenty-six feet in thickness; the last two feet of a blue shale. 



5. In varying shades of color; this sandstone is 168 feet in thickness. 



6. This formation was penetrated only one foot.** 

 Total depth of the well, 205 feet. 



♦See also Tenth An. Rep. Geol. Nat. Hist. Sur. Minn., p. 211. 

 **Compare note on this well; this Bulletin, p. 123, 



