Loess Hills

The Iowa Loess Hills, running nearly 200 miles along the Missouri River in western Iowa, are one of the rarest and most ecologically significant geological formations in the world — dramatic, steep-sided bluffs of windblown glacial silt (loess) deposited by the winds coming off the Missouri River glacier outwash plains after the last Ice Age, in some places accumulating to over 200 feet deep and creating a landscape as dramatic as the famous Loess Hills of China.

The unique, steep loess terrain, with its characteristic knife-edge ridges and sharply eroded ravines, supports a remarkable assemblage of rare dry-prairie, bur-oak savanna and loess-hill plant communities found almost nowhere else on Earth. The Loess Hills Scenic Byway (Iowa Highway 2 and Iowa 127 area) runs the length of the formation, and several state parks and wildlife areas protect the most dramatic sections. The Iowa Loess Hills are a treasured geological and ecological icon of Iowa.

The Iowa Loess Hills are explored via the Loess Hills Scenic Byway (a 220-mile National Scenic Byway along the Missouri River bluffs), with state parks (Preparation Canyon, Turin Loess Hills Preserve) and the Loess Hills State Forest providing hiking trails through the dramatic loess terrain, wildlife watching (prairie birds, white-tailed deer, wild turkeys), birding (the bluffs are on the Missouri River flyway), scenic driving, and photography of the dramatic ridge-and-ravine landscape. The scenic byway drive and hiking the sharp loess ridges are the signature draws. The combination of rare geology and rare prairie ecology is globally significant.

Spring (April through June) is excellent for prairie wildflowers and the most vivid green on the loess slopes, and fall brings golden prairie grass and brilliant oak color on the savanna; summer is warm but the ridges offer views. The managed prairie burns in the Loess Hills often happen in late spring — driving the byway after a burn reveals the landscape dramatically. Spring for wildflowers and fall for the golden prairie and oak color are the highlights — drive the scenic byway in spring or fall, stop at the state forest and preserve trailheads, and look for prairie-chickens and other native grassland birds.

The Loess Hills are part of the homeland of the Yankton Sioux, Omaha, Potawatomi and earlier peoples, who lived on and traveled the Missouri River bluffs. Euro-American settlement converted most of the native dry-prairie and savanna to farmland, leaving only the steepest, unplowable loess ridges with native vegetation. The scenic byway and the conservation lands protect these remnant areas. The Hills were recognized as one of the world’s rare loess landscapes. The Iowa Loess Hills preserve this extraordinary geological and ecological heritage, a treasured icon of western Iowa.

The Iowa Loess Hills were built by strong winds that blew vast quantities of fine glacial silt off the Missouri River outwash plains and deposited it on the bluffs to the east, during the late Pleistocene. The loess accumulated to depths of over 200 feet in places — some of the thickest loess deposits outside of China — and was then eroded into the characteristic knife-edge ridges, side ravines and steep slopes visible today. The loess is highly erodible and the ridges are sharply defined because the silt deposits vertically. The wind-deposited loess, the steep bluff topography and the erosion created this globally rare landscape.

The Loess Hills support rare dry-prairie and bur-oak savanna wildlife — greater prairie-chickens (one of their last Iowa strongholds), prairie rattlesnakes (uncommon), prairie dogs (at a few restored sites), dickcissels, Bell’s vireos, prairie warblers and other grassland birds, along with white-tailed deer, wild turkeys, coyotes and migrant raptors and songbirds on the Missouri flyway. The native prairie remnants on the steep loess ridges are critical habitat for a suite of Iowa’s rarest birds and plants. The Loess Hills offer excellent birding for prairie species, with prairie-chickens and rare dry-prairie birds among the highlights.

The Iowa Loess Hills protect one of the rarest and most endangered ecosystems in the world — the dry loess-hill prairie and bur-oak savanna found on the steep, south- and west-facing slopes of the loess ridges, where the thin, dry soils and the sharp topography have prevented conversion to farmland, preserving native plant communities otherwise nearly eliminated from Iowa. The system is maintained by fire; without prescribed burns, eastern red cedar invades and shades out the prairie. Protecting the native prairie, the prescribed fire regime and the unique loess geology sustains this globally rare ecosystem.

The Iowa Loess Hills hold a treasured place among the geological and ecological icons of Iowa — one of only two places in the world (the other in China) with loess formations of this depth and drama, a landscape of knife-edge ridges and rare dry-prairie ecosystems along the Missouri River, on the homeland of the Sioux and Omaha peoples. The Loess Hills Scenic Byway captures this rare landscape, largely unrecognized outside Iowa but globally significant. The Iowa Loess Hills are a cherished geological and ecological icon of western Iowa.

The Iowa Loess Hills run for about 200 miles along the Missouri River in western Iowa, from the Iowa-Missouri border north to Sioux City, accessible via the Loess Hills Scenic Byway (Iowa Highway 2 and connecting byway routes through the bluffs — well-signed and mapped by Iowa DOT). Key public access areas include the Loess Hills State Forest (multiple units in Monona and Harrison counties), Preparation Canyon State Park, the Turin Loess Hills Preserve, and Hitchcock Nature Center near Council Bluffs. The byway and most public lands are free. Check Iowa DNR and local tourism for current trailhead access, fees and trail conditions.

Iowa DNR, the Iowa Natural Heritage Foundation, The Nature Conservancy and local land trusts protect the Loess Hills through state parks, wildlife areas, state forest lands and private conservation easements. Prescribed fire (burns) is the primary management tool to maintain the native dry prairie against cedar invasion. Visitors help by staying on designated trails to protect the fragile loess slopes (which erode easily), respecting any fire management areas, not disturbing the rare prairie plant communities, packing out everything, and following all rules. Protecting the native prairie and the fire regime is essential for the globally rare loess ecosystem.

The loess ridges and ravines are very steep and the loess soil is highly erodible — stay on designated trails and do not cut across the slopes or go off-trail on the ridge faces (erosion damage is easy and lasting). The south-facing slopes can be very hot and dry on summer days (carry water and sun protection). The byway roads are paved but the side roads to preserves and state forest trailheads may be gravel and muddy in wet weather. Watch for rattlesnakes (uncommon but present on the dry prairie ridges). Respect the steep terrain, the fragile loess, the summer heat and the rattlesnakes.

The scenic byway is open to all; public access at state parks, state forest and preserves follows Iowa DNR and The Nature Conservancy rules. Stay on designated trails; off-trail travel on the loess slopes is not permitted (erosion damage). Collect no plants or animals (the prairie plants are protected). Prescribed fire areas are sometimes closed; respect any closure signs. Camping is at designated sites (state forest has some primitive camping; check Iowa DNR). Pets must be leashed at all Iowa DNR lands. Pack out all trash. Check Iowa DNR for current trail access, fire management areas and rules before visiting.

The cities of Council Bluffs (with the Hitchcock Nature Center, one of the best Loess Hills access points, and the Kanesville Tabernacle history) and Sioux City (with the Loess Hills Scenic Byway’s northern terminus and the Sergeant Floyd Monument), the Missouri River and the Nebraska border, the Preparation Canyon State Park area, and the western Iowa farmland define the region. The Missouri River valley and the Loess Hills define the region. The Loess Hills anchor the geological and ecological experience of western Iowa, a centerpiece of the scenic byway adventure.

Drive the Loess Hills Scenic Byway from Council Bluffs north to Sioux City on a clear spring day for the full ridge-and-ravine experience — stop at the Hitchcock Nature Center near Crescent for an excellent trail walk with panoramic Missouri River views, and at the Turin Loess Hills Preserve or Preparation Canyon State Park for the native prairie. Look for dickcissels and Bell’s vireos singing from the prairie in June, and for greater prairie-chickens (check with Iowa DNR for current reliable locations). Come after a spring prescribed burn for the most dramatic, open landscape.