94 IOWA ACADEMY OF SCIENCES. 



FEET 



Gravel, coarse, cross-bedded, iron-stained, cemented 

 in part into hard conglomerate; made up to con- 

 siderable extent of very badly weathered mate- 

 rial, manifestly an old gravel 40 



Down to the gravels this is the normal section for the region 

 and could be duplicated at hundreds of points. The ferretto 

 zone is well developed and its coloring is dark enough to show 

 excellently in a photograph. The drift and loess are identical 

 in every particular with that found throughout southern Iowa 

 and there can be no doubt whatever that the drift is Kansan. 



The drift shown in the east lobe is of the same character as 

 that overlying the gravels in the main face, and the identity of 

 the two has not been questioned as far as is known to the writer 

 by any who have visited the place. Among the latter may 

 be mentioned Professors T. C. Chamberlain, Albrecht 

 Penk, Samuel Calvin and S. W. Beyer. Prof. G. P. Wright 

 has seen the exposure but his opinion on this point is not 

 known to the writer. The drift in the east lobe lies at a con- 

 siderably lower level than in the main face, extending in fact 

 down to the bottom of the pit. As the railway near the station 

 just cuts into the top of the gravels a few feet, this was, when 

 first seen, interpreted to mean that the gravels formed a kame- 

 like ridge with a northwest- southeast trend and that the drift 

 had been laid down over this ridge running down over its side. 

 It was thought likely that there had been some erosion whereby 

 an eastern extension of the gravels had been cut away before 

 the drift of the east lobe was laid down, and that, accordingly, 

 the position of the drift indicated, or at least accorded with, a 

 certain time interval between the gravel and the overlying 

 drift. Recent studies fail to sustain this view. The Great 

 Western Railway company undertook to open up the gravels at 

 the point near the station where they showed above the track. 

 As the steam shovel traveled to the north it was found that the 

 gravel contained more and more clay until ordinary bowlder 

 clay was being handled, and the work was stopped. An exam- 

 ination of the east lobe of the old pit apparently indicates that 

 the same transition occurs there. In the photograph (Plate vi) 

 faint lines of stratification will be noticed running through the 

 bowlder clay. So faint are these in that portion some distance 

 from the gravels that they were at first entirely overlooked. 

 Re-examination showed, however, that the bowlder clay is 



