76 IOWA ACADEMY OF SCIENCES. 



disorderly arrangement seen in the area of eroded Maquoketa 

 shales, all rise approximately to the same level. The Kansan 

 drift is everywhere in this region overlain by loess. Mature 

 erosional topography, on a small scale, was developed on the 

 Kansan surface before the loess was laid down upon it. Sub- 

 sequent erosion of the friable loess has modified the curves of 

 the original profile lines to some extent, and so the surface 

 features which present themselves between PeostaandEpworth, 

 the next station west, have been classified under the name of 

 loess-Kansan topography. The region affords as typical 

 examples of this kind of surface carving as can be found scores, 

 or even hundreds, of miles back from the terminal margin of 

 the Kansan ice. 



The normal loess-Kansan surface, as seen between Peosta 

 and Epworth, is modified by a number of pahoid ridges between 

 Epworth and Parley, but west of the station at Parley the rail- 

 way enters immediately upon a new type of topography, upon 

 a plain of lowan drift. The lowan is much younger than the 

 Kansan. Its surface is nearly level; it is absolutely uneroded; 

 it is not covered with loess; and large granite bowlders, pro- 

 jecting conspicuously above the surface, catch the attention 

 and awaken the interest of even the unscientific traveler. It 

 is a narrow lobe of lowan drift which is traversed by the rail- 

 way between Parley and Dyersville. The lobe occupies a low 

 plain as if the lowan ice had flowed out in a long tongue 

 between ridges of eroded Kansan. These rain-sculptured 

 ridges, now covered with loess, are recognizable on either 

 hand from the platform of the coach. The level, uneroded 

 lowan surface afforded the engineer in charge of the location 

 of the railway line an opportunity of which he was quick to 

 take advantage. This narrow lowan lobe between Parley and 

 Dyersville is as typically lowan as any area in the state; but 

 west of Dyersville, if the observer wishes to pursue the subject 

 further, he may enter upon the great lowan plain, and all the 

 way across the counties of Delaware, Buchanan, Black Hawk, 

 and westward to the Wisconsin moraine in Hardin, he will fiad 

 his whole horizon occupied by a surface showing only the 

 gentle undulations left by the melting lowan ice. Erosion has 

 played no part in producing the land forms which characterize 

 ninety-nine per cent of the lowan area. Except in the immedi- 

 ate neighborhood of the streams the topography is construc- 

 tional. 



