3IO 



SCIENCE 



[Vol. XIX. No. 487 



ARTESIAN WELLS IN IOWA. 



The demand for artesian waters in the State of Iowa is 

 not to be connected with unfavorable climatal conditions. 

 The State is well watered; a considerable number of rather 

 large streams and innumerable smaller ones combine to make 

 it, from a hydrographic standpoint, unique among prairie 

 States. The annual rainfall is a little more than thirty-five 

 inches, and chiefly comes at a time of year when every crop- 

 necessity is fully supplied. The main grounds upon which 

 artesian waters are sought, therefore, are, first, the con- 

 venience of such flows for farm and urban use, and, second, 

 the supposed purity of such waters. These are the prime 

 reasons which have induced exploratory drilling, the 

 chief results of which it is the purpose of this notice to 

 record. 



About four-flfths of the area of Iowa has now been demon- 

 strated to possess artesian conditions. Most of this area lies 

 northward of a line which may be drawn across the State, 

 in a north-westerly direction, from near Keokuk to Sioux 

 City, except in the igneous area indicated below. South of 

 this somewhat arbitrary line but one or two artesian flows 

 are known ; these appear to be connected with the Nebraska 

 artesian area, and are in the immediate neighborhood of the 

 cities of Omaha and Council Bluffs. By reference to the 

 sketch-map accompanying, it will be seen that the greater 

 number of the wells lie along the DesMoines River or its 

 tributaries; this distribution, which is well marked, is to be 

 correlated with the distribution of the great terminal mo- 

 raine, within which most of these wells are situated. This 

 peculiarly interesting feature is further discussed beyond. 

 The very deep and permanent artesian wells lie mainly east 

 and north of the line above mentioned ; or, better still, east of 

 a line drawn north and south through the city of Ottumwa, 

 No. 169 on the map. With but a single exception, that at 

 Washington, No. 54 of the map, these deeper borings furnish 

 abundant flows of water. But there are also, east of this 

 north and south line, two smaller areas of shallow wells 

 whose characters are essentially identical with those exhibited 

 by the wells within the terminal moraine. One of these lies 

 along the Iowa River (see map, Nos. 60-66, etc.); the other, 

 and by far the smallest single artesian area in the State, is 

 in the valley of the Wapsipinnicon River, in Bremer County 

 (see map, Nos. 11, 12, and 42). The shallow wells, there- 

 fore, constitute well-defined groups; the deep wells are widely 

 scattered. 



It has been found convenient to classify the Iowa artesian 

 wells in terms of the geological structure which they exhibit. 

 To the shallow wells, those that form groups and which 

 present similar geological sections, the term " glacial 

 wells," or wells of the first class, has been applied. To all 

 others, no matter what may be the geological age of the 

 strata into which they may pass or in which they end, 

 the term "deep wells," or wells of the second class, may be 

 appropriated. There is no distinguishing mnemonic on the 

 map, by which these wells may be differentiated. 



A few important deep borings have been made, in various 

 parts of the State, but more particularly in tlje north-western 

 and south-western portions, in which artesian waters were 

 not found. But, in the greater number of these borings, 

 the water rose to constant heights, always, however, some 

 distance below the top of the boring. These are called on 

 the map "deep wells not artesian," and are indicated by a 

 specific mnemonic, as in the Glenwood well, in south-western 

 Iowa (see map, No. 120). 



In depth the glacial wells range from forty feet to two 

 hundred and fifty feet in a few cases; this feature is depen- 

 dent on the relations of the borings to pre-glacial drainage, 

 on the one hand, and to the thickness of the morainic mate- 

 rials, which is a variable, on the other. A generalized sec- 

 tion may be given as follows from the sequence disclosed in 

 Hancock and Wright Counties: — 



Soil 1-5 feet. 



Bowldery clay, wltli water 10-50 feet. 



Bluish, bowldery glacial clays 30-12 - feet. 



Sand and gravel 8-20 feet. 



Sand and gravel, with water 15-25 feet. 



These materials are irregularly distributed over the surface 

 of the State, and exhibit a variable relation. However, 

 whenever the gravels and sands of the lower series are 

 reached, especially in the valleys of the larger streams 

 within the terminal moraine, flowing wells are likely to be 

 obtained. 



The deeper artesian wells, or those which present the char- 

 acteristic feature of penetrating the country rock, are typified 

 by the following section, which is that of the deep artesian 

 well at Cedar Rapids: — 



No. Feet 



1. Darli-gray limestone 50 



2. Light-gray limestone 85 



3. Gray limestone 40 



1 4. Coarse-grained, reddish-brown limestone 65 



* 5. Coarse, brown, and very porous limestone 6 D 



6. Coarse, light-brown limestone, raised with shale 30 



7. Shale 20 



8. Coarse, darl£-gray limestone 25 



9. Coarse, light-gray limestone 45 



10. Tough, blue clay 200 



11. Reddish-brown sandstone 205 



12. Shale 5 



13. Darli, bluish-gray sandstone 65 



14. Shale 1 



15. St. Peter's sandstone 50 



16. Gray sandstone 74 



' 17. Brownish sandstone 40 



> 18. Coarse-grained, porous, brown sandstone 370 



19. Light sandstone 8S 



20. Dark-colored and hard sandstone 42 



21. Brown, very close-grained and hard sandstone 14) 



2.'. Blue clay 100 



23. Soft, reddish-brown sandstone 161 



24. Potsdam sandstone 203 



25. Red sandstone 75 



' Contains water. 



Over the eastern third or more of Iowa, east and north of 

 the line drawn from Keokuk to the vicinity of Sioux City, 

 as above mentioned, thence north-easterly to Worth or 

 Mitchell Counties, the St. Peter's Sandstone may be reached 

 in deep wells, and flowing water found. North of that part 

 of the line which extends north-easterly from Sioux City 

 flowing water will not be found, if the indications of the 

 strata penetrated in the Hull, Sioux County, wells are re- 

 liable. From that place igneous rocks, presenting a volcanic 

 facies, have been submitted to us. 



The south-western part of the State, that is, all that part 

 of Iowa which lies south of the first arbitrary line above in- 

 dicated, will not furnish artesian waters. The section, which 

 is given elsewhere, of the Glenwood deep-boring furnishes 

 the most complete vertical section of the carboniferous rocks, 

 which is exhibited in Iowa. It further affords no hope that 

 artesian waters will be reached at reasonably profitable depths 

 in that portion of the State. 



Readers of Science who may be interested in the details of 

 an investigation, of which this notice is a brief abstract, may 

 receive the full paper on addressing the Iowa Weather and 

 Crop Bureau, DesMoines, Iowa, under whose auspices the 

 work has been done. E. Ellsworth Call. 



