PUBLIC PARKS OF IOWA 93 



GEOLOGY OF WEBSTER COUNTY. 

 By Frank A. Wilder, Geologist. 



The Coal Measure sandstones are the striking stratigraphic feature 

 in the southern part of the county where a maximum thickness of sixty 

 feet is exposed. Most of the layers are ferruginous, but near Lehigh 

 the upper courses at certain points are cemented with carbonate of lime. 

 The bond between the grains is slight when iron is the cementing sub- 

 stance. The layers containing carbonate of lime, however, are firm and 

 suitable for building. Typical exposures of these standstones may be seen 

 on Prairie creek in Otho township, section 35, the so-called copperas beds, 

 and at Wildcat Cave in Pleasant Valley township, section 11 south- 

 wesit quarter. 



Webster county lies wholly within the area that was covered by the 

 last great ice invasion, and the drift of this ice sheet, called the Wisconsin, 

 forms almost everywhere the surface material. Limited areas covered 

 by glacial material that had been recently reworked by streams, or by 

 detnitus formed by the very recent weathering of cliffs along streams 

 are the only regions not drift covered. So recently was this drift depos- 

 ited that erosion has but slightly contributed to the topographic features 

 of the county. Only ,in the immediate vicinity of the Des Modnes river 

 and its tributaries are the results of water action apparent. Viewed from 

 the valleys of the streams, the landscape seems extremely rugged, and 

 it is a matter of constant surprise that, in a region so typically prairie, 

 scenery so beautiful abounds. The sides of the valley are steep and 

 well wooded from top to bottom. After ascending the sharp slope, how- 

 ever, the climber finds himself at once on the level prairie where often 

 for miles he can see the stream as it flows through its V-shaped valley. 



The entire county is drained by the Des Moines river and its tribu- 

 taries. Most of the branches rise within or barely outside of the county 

 and while still within its limits unite with the parent stream. Lizard, 

 Soldiier, Deer, Holaday, Brushy, Skiller and Prairie creeks answer this 

 description. East and West Buttrick creeks, which drain four town 

 ships in the southwestern corner of the county, contribute their waters 

 to the Raccoon which they meet in Greene county. The drainage system 

 is not elaborate. None of the creeks in the county are perennial farther 

 than a mile from their mouths. The creeks have no well developed 

 subordinate feeders, and large stretches of country are dependent on arti- 

 ficial drainage. The contrast that Webster county presents in this par- 

 ticular with certain other parts of the state is made plain by a map 

 drawn on a scale as limited as that of the railroad commissioners. The 

 accompanying sketches which reproduce Ringgold and Webster counties 

 illustrate fairly the difference in drainage between Webster county and 

 the southern part of the state. Any county in the three tiers near the 

 southern boundary would serve for contrast as well as Ringgold. 

 Sloughs and ponds are common throughout Webster county, their num- 

 ber and size varying with the reason of the year. The percentage of the 

 land that is for this reason kept from cultivation, however, is not great 

 Yearly the number of ponds is being reduced by artificial drainage. Iowa 

 Geological Survey, Vol. XII, pp. 85-6, p. 69 and pp 72-3. 



