Loess Hills Preservation Society


Preserving our most Precious Natural Resource

The Loess Hills (pronounced “luss”) borders the Missouri River extending north-south along the western edge of Iowa into northwest Missouri. The Hills are a unique, world-class landform; with the exception of China, no where else are the loess deposits found at such depths.

The Loess Hills are an angular band of rugged, prairie-topped hills rising up from the flat bottomland of the Missouri River. Steep slopes heated by the sun and wind support a unique assemblage of plants and animals that are more commonly found further west in the Great Plains. These species include the Great Plains toad, yucca, cowboy’s delight, six-lined racerunners, and even the prairie rattlesnake. The Hills were formed between 24,000 and 14,000 years ago from silt blown in from the Missouri River floodplain. This silt known as “sugar clay” by the locals easily erodes once the vegetation has been removed. Erosion is one of the leading problems in the Loess Hills caused by activities such as mining and removal of the loess for fill material.

The Loess Hills house the largest tracts of remaining prairie in Iowa. In Iowa less than 1/10th of 1% of the historical prairie is left and it is in the Loess Hills that the majority of the prairie is left. These remnants are threatened by expansion of woody plants such as eastern red cedar, once controlled by periodic fires. Other threats include continued urban development.