196 
IOWA ACADEMY OP SCIENCES. 
Taking No. 17 to represent the base of the Bertram beds the 
succeeding numbers are referred to the following formations: 
THICKNESS 
IN FEET. 
Nos. 16-15. Niagara and Le Claire 349 
Nos. 14-13. Maquoketa 276 
No. 12. Galena 65 
No. 11-7. Trenton..... 240 
No. 6+. St. Peter 25 
Nos. 5-4. Upper Oneota 125 
No. 3. New Kichmond 55 
No. 2. Lower Oneota 175 
No. 1. Upper Saint Croix to bottom of well, 1,462 feet 62 
The first artesian well at Cedar Rapids, which reached the 
Algonkian floor, disclosed the base of the sandstone referred to 
the Upper Saint Croix at 1,690 feet and the following strata suc- 
ceeding : 
FORMATION. THICKNESS 
IN FEET. 
Shales. Lower St. Croix 100 
Sandstones. Potsdam 360 
Quartzite. Sioux, to base of well at 2,225 feet 75 
Points of special interest in the above section are : 
(1) . The thickness of the Niagara-Le Claire. Being but 
about ten miles distant from the thickest known outcrop of the 
Le Claire, where it aggregates ninety feet, it is believed that 
we have here a reliable measure of the probably maximum 
thickness of the formation; verifying White’s estimate of 350 
feet. 
(2) . The thickness of the Maquoketa, previous estimates not 
having exceeded 100 feet. 
(3) . The clear distinction between the Galena and Trenton, 
not marked in the record of the first artesian well*. In the 
driller’s record of this well as published by R. E. Calif, the 
entire Galena- Trenton limestones are termed “sandstones.” 
(4) . The presence near the base of the Trenton of a petrolif- 
erous shale, in other states the source of natural gas and oil. 
(5) . The reduction in the thickness of the Saint Peter given 
in the records of the first well at 116 feet. 
(6) . The division of the Oneota by a well defined sandstone. 
The equivalent of the New Richmond sandstone of Minnesota. 
The Upper and the Lower Oneota dolomites, whose joint thick- 
ness is 300 feet, were published as “ sandstones ” in the record 
of the first artesian wellj . 
*Iowa Geol. Surv., vol. IIJ, p. 195. 18>5. 
tProc. Iowa Acad. Sci., vol. I, pt. ii, p. 58. 1892. 
tLoc. cit., 58. 
