130 Artesian Well Boring in Southeastern Minnesota — Hall. 



By consulting the accompanying plate (Plate II) it will be 

 seen that there five or six of these layers of sandstone. All of 

 them yield water, the lower ones very freely. 



Successful well boring for water depends on certain conditions,, 

 partly physical and partly geological. They may be briefly sum- 

 marized as follows: 



A. There must be a porous stratum of rock lying between 

 two impervious strata. 



B. There must exist an area at the surface of the ground, 

 where the porous stratum is exposed to saturation from rainfall. 



C. There must be a sufiicient fall from this exposed area to 

 the region of the wells to insure a steady and abundant flow of 

 water. 



D. There must be a sufficient freedom from fissures, faults 

 and dikes to insure a steady flow without great loss of water from 

 the rainfall district to the region of the wells. 



It is not necessary that the porous stratum be a sandstone 

 further than the natural qualities of the rocks themselves deter-^ 

 mine the question. No other rock species is sufficiently porous to 

 permit a free flow through it of large quantities of w^ater, save 

 by fissures, and these form an unreliable passageway, even more 

 likely to cause defeat than to insure success in the search for 

 water. 



The sandstones of southeastern Minnesota can very easily be 

 parallelized by means of the deep wells already bored; and their 

 general relations to each other, and to the interbedded limestones 

 and dolomites can be made out. 



Mr. Warren Upham has of late given considerable attention 

 to the stratigraphic relations of these sandstones, and he has gen- 

 erously placed his manuscript at mydisposal. In preparing these 

 statements, and in sketching the accompanying plate, I have 

 drawn freely from Mr. Uphanrs notes. 



1. The Glacial Drift. — In enumerating briefly the forma- 

 tions in the southeastern portion of our state with reference to 

 their water-bearing qualities, it is nat necessary to do more than 

 mention the glacial drift. This deposit, scatteied almost entirely 

 over the state, is the universal source of our ordinary well water. 

 This is usually secured by excavating, rather than by boring. Yet 

 where boring is done, it is no unusual thing to secure a flowing 

 well by penetrating the rock to where a layer of clay covers the- 



