Iowa the beautiful: Looking at the landform regions of our state

My husband and I took a trip to Utah this summer.

We were enamored by the beautiful landscape, with red rocks rising out of sandy floors, hoodoos sprouting out of canyon lands, short scrub trees dotting desert landscapes.

During a drive through Zion National Park, we overheard a student on the bus say “I haven’t seen this much green in three years.”

This much green? There were relatively few trees in the giant canyons, and the grasses were sparse as well.

When we arrived back in Iowa and were driving home, we did start to notice just how much green was around us. Tallgrass prairie plots, corn fields, bright ditches and yards — I guess I can see why people comment on how green Iowa is.

When we think of beautiful landscapes, Iowa is not usually the top state we think of. However, the closer you look, the more you do start to notice just how diverse and beautiful the state is.

(Check out this craft using different soil samples.)

Iowa actually has between seven and 10 different landform regions, depending on who you talk to, and each is more diverse and beautiful than the last. Take a drive across the state, and sometimes you’ll think you’ve entered an entirely different area.

Graphic of Iowa landforms

Map courtesy of Iowa Geological Survey

Northwest Iowa Plains

Dickinson County is partially located in the Northwest Iowa Plains region and partially in the Des Moines Lobe region. The Northwest Iowa Plains has a gently rolling landscape that was once covered in tallgrass prairie and is now dominated by agriculture.

Map graphic

Map courtesy of Iowa Geological Survey

It is a largely treeless region that sits at the highest elevation in the state and has the lowest rainfall. It does have a branching network of streams and rivers that stretches out throughout the region, giving it good drainage.

Beneath the surface, northwest Iowa sits on a bed of glacial drift covered by a layer of windblown loess. Landforms of Iowa by Jean C. Prior says, “The mantle of silt generally thins in a southwest to northeast direction from about 16 feet in Plymouth County to 4 feet in Clay County.”

Des Moines Lobe

The Iowa Great Lakes portion of Dickinson County resides in the Des Moines Lobe region of the state. Iowa’s Natural Heritage, published by the Iowa Academy of Science and the Iowa Natural Heritage Foundation, calls this the Wisconsin Surface region.

Map graphic

Map courtesy of Iowa Geological Survey

Continental glaciers helped affect much of Iowa’s landscape, but the Des Moines Lobe was the last part of the state touched by glaciers, and you can still see actual shapes that resulted from these. The landscape lacks a cover of windblown silt, so the remnants of glacial movement has not been filled in and is still obvious.

For instance, large crevices within the ice became filled with deposits of sand and gravel when the glaciers melted, and those deposits remain as kames today. The Ocheyedan Mound is a glacial kame, as is the hill in Kenue Park.

(Learn about Kenue Park and its glacial kame.)

Bowl-shaped depressions called kettles, like the Freda Haffner Kettlehole outside Milford, were created when large, isolated blocks of clean ice melted slowly.

Nearly all of Iowa’s natural lakes are found in the Des Moines Lobe, including East and West Lake Okoboji and Big Spirit Lake.

Iowan Surface

East of the Des Moines Lobe is the Iowan Surface region, which acts as a transition between woodlands to the east and the tallgrass prairie to the west. Compared to other regions around it, the Iowan Surface is considered rather subtle with long, rolling slopes and open views.

Map graphic

Map courtesy of Iowa Geological Survey

One interesting aspect of this region is the presence of glacial erratics, large boulders of rock typically found in Canada, Minnesota and Wisconsin that were dropped by melting glaciers and have withstood wind and soil erosion through the years.

Paleozoic Plateau

Drive through northeast Iowa, and it’s like you’re in a different state. There are forests, caves and plants that aren’t found anywhere else except in the Paleozoic Plateau, so named because it is the result of rock erosion in the Paleozoic age.

Map graphic

Map courtesy of Iowa Geological Survey

In geologic time, rocky deposits in the area hardened into more brittle rock and were broken by movement in the Earth’s surface. Large cracks in the rock, called joints, create the blocky shapes and sheer cliff faces that are seen along roadways in the region. Springs are commonly found along steep valley sides where erosion has intersected with groundwater.

Missouri Alluvial and Mississippi Alluvial

Rivers, such as the Mississippi and Missouri that border Iowa, created flat-floored corridors called alluvials. These are constructed by the debris and sediment that the water carries and then leaves behind as it slows in certain areas.

Map graphic

Map courtesy of Iowa Geological Survey

Map graphic

Map courtesy of Iowa Geological Survey

There are other alluvial plains in Iowa, but the two bordering the major rivers in the state stand out on topographic maps.

Iowa’s Natural Heritage also splits apart part of the Mississippi Alluvial region into Sandy Provinces. “Scattered throughout Iowa are areas of pure sand, deposited by stream action…” Unusual species of plants and animals, such as the ornate box turtle, hognose snake and lark sparrow are found in these areas. Landforms of Iowa calls this area Iowa-Cedar Lowland.

Map graphic

Map courtesy of Iowa Geological Survey

Loess Hills

One of the state’s most distinctive and well-known landscape regions is the Loess Hills area in western Iowa. They are composed of gritty sediment known as loess, the German word for loose or crumbly.

Map graphic

Map courtesy of Iowa Geological Survey

Loess is a type of windblown silt, usually quartz. It is found covering thousands of square miles in the Midwest as well as in central Europe, Russia and northern China. The Loess Hills is simply a thick enough deposit to cover the surface and even form its own landscape.

The thickness of loess in the Loess Hills is usually at least 60 feet, with depths of 150-200 feet having been recorded in certain areas.

Southern Iowa Drift Plain

The largest of Iowa’s landform regions, this was created by glaciers but their remains — kames, kettles, and the like — have been covered up through time. The only identifying factor is that 10 to hundreds of feet of glacial drift covers bedrock.

Map graphic

Map courtesy of Iowa Geological Survey

This area has rolling hills, most of which slope toward a river or stream or another type of drainage. Erosion and windblown loess have also contributed to the sprawling landscape.

Riverine Systems

Iowa’s Natural Heritage specifies Riverine Systems as another landform, Landforms of Iowa does not. These are deep valleys formed by major rivers that are wooded and moist. Many animals make their homes in these areas.

Iowa the Beautiful

We hear it from friends and family that live out-of-state, on TV shows that happen to mention Iowa or the Midwest — “That’s flyover country.” What they mean is, no one cares. It’s not pretty. Why would we visit there?

But Iowa is beautiful. It has rolling hills, majestic rock faces, hidden caves, flowing rivers. If we tune our eyes to its subtleties, we’ll also see its beauty.

(For a more detailed description of Iowa’s landforms, check out Landforms of Iowa by Jean C. Prior.)

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