IOWA ACADEMY OF SCIENCES. 55 



as seen at Le Claire*, but he assumes that the inclination of the 

 beds is due to folding and uplift subsequent to their deposition. 

 On this assumption the Le Claire limestone would have a thick- 

 ness of more than 600 feet, whereas the maximum thickness 

 does not exceed 80 feet, and the average over the whole area is 

 very much less. Prof. A. H. Worthenf studied this limestone 

 at Port Byron, 111., and Le Claire, Iowa, and describes it as 

 " presenting no regular lines of bedding or stratification, but 

 showing lines of false bedding or cleavage at every conceivable 

 angle to the horizon." He assigns to these beds a thickness of 



r 



Figure 2. Inclined undulating beds o"*the Le Claire stage near >Jewport, Iowa, 



fifty feet, but he offers no explanation of what he calls "false 

 bedding or cleavage." In White's report on the geology of 

 lowat the oblique bedding seems to have been taken as evi- 

 dence that a line of disturbance crossed the Mississippi river at 

 Le Claire with a direction nearly parallel to the Wapsipinicon 

 valley. This apparent disturbance was last recognized about 

 three miles west of Auamosa. The angle of dip it is said has 

 reached in some places twenty-eight degrees with the horizon. 

 McGee in discussing the Regular Deformations of Northeastern 

 Ioioa% quotes Dr. White on the Wapsipinicon line of disturbance 



* Rept. on the Geol. Surv. of the State of Iowa, Hall and Whitney, vol. I, part I, pp. 

 73-74. 1858. 



+ Geol. Surv. of 111., vol. I, p. 130. 1865. 



* Rept. on the Geol. Surv. of the State of Iowa. Charles A. White, vol. I, p. 133. 1870. 

 § Pleistocene history of Northeastern Iowa, p. 340. 1891. 



