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DAVENPORT ACADEMY OF XATURAI, SCIENCES. 



River and 25 or 30 feet above the present surface of the valley about 

 this point. At the top of this formation is a quite regular horizontal 

 and well defined line, showing the surface at the period immediately 

 succeeding the time of the deposition of the drift. 



Above this is the usual loess or " yellow clay " (b) to the depth of 

 some 70 feet and reaching a level of about IBO feet above the datum 

 line of low water mark. 



A section of the underlying strata to the depth of 240 feet has been 

 obtained by a boring for water by Mr. M. Frahm some years since. 

 This boring was made at the side of Harrison street, a short distance 



West. rScale. 120 leet to an inch. | 



a. Blue clay or glacial drift; b, Telle w clay or Loess; c, Limestone; d. Fire 

 clay; e. Limestone; f, Cave; H, Harrison street; R, Ripley street; H-R, Grade 

 of Sixth street: 1, Low water level of Mississippi River, 5.5.?.22 feet above sea 

 level. 



below Sixth, where the grade is two feet lower than at 

 Sixth street. 



The boulder clay (a) extends to the depth of 40 feet 

 below the surface of the street, making a total depth 

 of 70 feet of this formation. Next below is a bed of 

 limestone (r) ten feet in thickness, resting upon a stra- 

 tum of fire-clay (d) eight feet thick. 



From this point downward the boring was continued 182 feet far- 

 ther in a bed of solid limestone (() excepting that at the depth of 142 

 feet from the surface the drill dropped eight feet in a small cave (/) in 

 this rock. This cave contained water, and a pump was put in. After 

 pumping nearly 1000 barrels of water, the cave was emptied and 

 gradually refilled when the pumping was stopped, showing that the 

 supply was only from the surrounding earth. The boring was then 

 continued 90 feet farther, reaching the full depth of 240 feet from the 

 street, 178 feet below low water mark of the Mississippi river, which 

 is distant nearly half a mile, south. 



