The Varied Character of the Des Moines River Valley in Central Iowa

The drainage system on the Des Moines River is quite varied between Humboldt and Des Moines. The variation in drainage characters is highlighted on a map prepared from aerial photographs and topographic sheets. The northern part of this area is associated with the Mankato drift sheet and is characterized by poorly developed, non-integrated drainage. The central part of the drainage system in Boone County flows across the Cary ground moraine. In this area the tributaries are short, intermittent, and deep, and appear as gullies and washes. Just south of Des Moines, the drainage makes another sharp change, and in this area is associated with the Kansan drift. It is well integrated and featured by a relatively small number of far-reaching primary tributaries. It seems to be more than coincidental that the change in character of the drainage is so closely associated with the relative ages of the drift sheets comprising the drift plain