68 PUBLIC PARKS OF IOWA 



atum commutatum, Festuca nutans, Bromus purgans, Thalictrum purpur 

 ascens, blue grass (Poa pratensis). 



In a paper on the Keosauqua area for southeastern Iowa I touched on 

 the more important scientific features of the region in general. In a 

 former visit long before the matter of state park sites for this area was 

 taken up I felt that some of this interesting region should be set aside 

 for park purposes. The region is an interesting one. This part of Van 

 Buren county, like the remainder, was covered with the Kansan drift. 



W. H. Stevenson, P. E. Brown and G. E. Corson and W. H. Reid state 

 that "It extends to a depth of 50 to 100 feet and is somewhat thicker 

 in the southwestern than in the northeastern part of the county. It 

 consists of two well marked divisions of boulder clays, a lower blue clay 

 and an overlying yellow clay, both of which include more or less sand 

 and gravel. There is no well defined boundary between these two clays, 

 but they grade gradually into each other. The lower clay is dark blue, 

 compact and hard and filled with pebbles and small boulders. It varies 

 in thickness from a few feet up to 75 feet. The overlying clay is usually 

 a buff to reddish-yellow in color and it frequently contains sandy areas. 

 It contains more life than the underlying material. Usually the yellow 

 clays vary from 25 to 50 feet in thickness. 



"At some previous geological time, a layer of fine dust-like, ash-colored 

 material, called loess, was deposited over the glacial drift. Much of this 

 material has been washed away since its deposition, especially along 

 the Des Moines river, and the remainder forms a thin covering over the 

 upland areas. This loess covering is usually 2 or 3 feet and never more 

 than 10 feet in depth. 



"Along the rivers in the county there are terrace soils, or former 

 bottom lands which have been raised above the overflow of the streams 

 by the shrinkage in volume of water or by the deepening of the channel 

 of the stream. There are also several bottom land soils, occurring ad- 

 jacent to the streams and subject to overflow. 



"The soil of the area under consideration is a terrace soil known as 

 the Calhoun silt loam. On a part of the area there are outcrops of a 

 limy sandstone on which ferns abound. Most of the area is embraced 

 in the Calhoun silt loam. 



"The surface soil to a depth of 10 to 12 inches is composed of brown 

 or grayish brown, compact, but fairly friable silt loam which when dry 

 often appears almost white. In some areas the surface soil is some- 

 what darker than the typical. Beneath the surface there is a layer 3 

 to 4 inches thick of whitish or grayish white mealy silt loam, which 

 changes below into a gray clay loam mottled with brown. The material 

 from 20 to 24 inches usually becomes a drab or bluish gray, plastic silty 

 clay mottled with yellow and brown. Below 30 inches the color becomes 

 lighter with mottlings of yellow and gray. 



"In topography this soil is level or undulating to slightly sloping. The 

 slope from the terrace to the bottoms is gradual, extending for as much 

 as one-eighth of a mile in length and this slope is often cut by ravines. 

 Small streams frequently cut up the larger areas. The elevation above 



