WHAT ARE THE LOESS HILLS?

Along the western edge of Iowa, and reaching into South Dakota and Missouri, is a line of unusual hills hundreds of miles long. They rise up sharply from an otherwise nearly flat landscape, stark and steep. It’s a place of wonder, where the soil type produces mysterious features—wide, evenly spaced stair steps; spur ridges with the appearance of the pinched-up edges of a pie crust; thin ridges scarcely wider than a deer path. The width of the landform varies, some places half a mile wide, other places three miles across. Rivers intersect the system of hills, flattening the ground between, leaving multiple fingers resting on the level plains.

Named for the soil type, the Loess Hills have an ice age story, one repeated in only one other location on Earth. The ancient bed of the Missouri River, ground down into fine particles by glaciers, was revealed as the waters receded. Winds, which were primarily from the west, picked up this fine loess dust and dropped it on the eastern edge of the river bed, where it piled into depths hundreds of feet deep in places. The hills are a gift from the river, carried in on the breeze. While loess soil itself isn’t rare, the deep deposits are. The only other place where the remarkable depth of loess soil compares is in the Yellow River region in China, southwest of Beijing.

Towns and cities are staggered throughout the hills along with some protected areas. You might think of Council Bluffs, Iowa, or Waubonsie State Park, or The Nature Conservancy’s Broken Kettle Grassland north of Sioux City, and they’d all be a part of this system. 

Learn more at my Loess Hills Conservation and/or LoHi Trail pages.