Geographical Features of Iowa

When we think about glaciers, we think about Alaska and Antarctica. What does Iowa have to do with glaciers? Iowa has everything to do with glaciers! Continental glaciers were one of the first and most significant geological processes that have shaped Iowa. Between 2.6 million to 10 thousand years ago, several glaciers from the Canadian Arctic paved through the United States, plowing through Iowa on the way. Some have even been identified to come back several times! Most of these glaciers are classified as either Pre-Illinoian or Wisconsin glaciers. As these glaciers passed over Iowa, they eroded much of our land, creating hills and valleys, as well as depositing rocks and sediment called glacial drift. These processes created many of Iowa’s landform regions that we see today.

During the later glacial periods, Iowa was mostly ice free, and most of the glaciers lingered in the northern states, never to come again. Melting glacial water created several rivers and streams, which eroded much of Iowa’s land. Over time, many of the hills and valleys created by the glaciers were lost due to erosion, and prairies took over Iowa, thriving on the rich minerals provided by glacial drift. By then, the glaciers were long gone, but their impact still lasts to this day.

Click on the different landscape regions to see what kind of glaciers they were impacted by, and when. The blue areas indicate Wisconsin Glaciers, the green areas indicate Pre-Illinoian Glaciers, the purple area indicates the Des Moines Lobe Glacier, and the white areas have minimal to no interaction to glaciers. In addition, you can use the buttons below to just view the areas that have been impacted the same. You can click the location button for your location, or search up a place to find out how your location was impacted by glaciers.

Iowa is one of the best places to farm land, but its soil didn’t just magically become like this. The shaping of Iowa that makes it so unique first starts in the Des Moines Lobe, the most recent glacier of Iowa. This massive, prehistoric glacier that formed and paved the way for present day Iowa helped create our fertile soil that positively impacted our agricultural economy.

After retreating and returning multiple times, the Des Moines Lobe completely changed the area and set off a chain reaction of land improvements. One of these changes is the Loess Hills. Once the Des Moines Lobe evacuated Iowa due to rising climates, excess amounts of murky meltwater water from the glacier fled down south to the Missouri River. This water then froze in the dry winter and left a dusty soil called loess to emerge. This dust soon got picked up by the wind. The heaviest particles were the first to deport, eventually piling up into the Loess Hills. The remaining lighter particles eventually spread out across the Midwest. This lead the way for plants such as prairie grasses.

The Des Moines lobe created glacial till, eroded and scratched bedrock to create parent material - which is "...geological material from which soil forms." (Iowa PBS, n.d.) - and flattened out the land. Because of these changes, prairie grasses were able to grow, which in turn kept the land in place, broke up rocks with their fibrous roots, and gave nutrients back to the soil. You can think of the grasses as a blending machine, and the dirt as the ingredients to a smoothie. Though the blending machine turns up it’s contents, it keeps the ingredients all in one place, creating a delicious smoothie with healthy nutrients released from the blender.

Swipe the map on the left to see the Des Moines Lobe compared to the rivers of Iowa and the Loess Hills. The left side shows the Des Moines Lobe compared the Loess Hills. The right side shows all the river and streams of Iowa. The rivers and streams will only show up if zoomed in.

The Loess Hills are an iconic region in Iowa, with sharp, angular hills covered in native grasses and sparse trees. The topography in the Loess Hills contrasts much of Iowa. Its hills aren't like the gentle slopes most people picture. Instead, they have crooked, pointed ridges, with rippling terrain. A large number of drainageways is to thank for this interesting terrain; they've created several features such as covered hollows, skinny ravines, and steep gullies.

The Loess Hills are mainly compromised of a sediment called loess. The word loess comes from the German word löss, but it dates back to the Swiss German word lösch, which means loose. This fits well, for loess is a very crumbly and loosely packed, yet it is strong enough to form sturdy landforms. Loess occurs in many areas around the word, such as northern China, North America's Great Plains, central Europe, and certain areas of Russia and Kazakhstan. The thickest areas of loess occur in two places: along the Huang Ho (Yellow River) in China, and by the Missouri River in Iowa. Loess is formed when fine dust slowly piles up in a certain area. This dust can be caused by wind erosion in deserts, or in our case, erosion from glaciers.

Loess is creates very rich and healthy soil for plants. It's chock full of minerals, and has excellent soil drainage. Farmers around the world have used it to grow healthy crops. While loess is easy to till for farming, it erodes very slowly, so our Loess Hills aren't going anywhere for a while. Native grasses and prairie plants have taken advantage of the Loess Hill's fertile soil, and have spread over the hills, holding the land firmly together. This combination of plants and hills have made the Loess Hills a marvelous sight, sure to please anyone with its natural beauty.

Scroll Around to see the different areas where Loess occurs around. Click on the points to find out the name of the location. Note that the points aren't located exactly where the loess occurs; it only points out the general location. How close the loess is to the point depends on how specific the location is.

The Northwest Iowa Plains are a diverse and eye-catching plain to all. From the many glaciers that passed through, to gently rolling landscape creased and defined by streams that drain the plain, this area creates a distinctive combination that dominates other bordering regions. The streams play a huge part of the plain's dendritic water system, and the glaciers that once flowed through it gave the land a boost, such as flatter land and a diverse amount of soil. Now covered in medium to thick layers of loess that covers mixture of glaciers till, you can study the uniform density of the stream's drainage where both the Pre-Illinioan and Wisconsin glaciers passed over.

"This uniform density of stream drainage is important in unifying a region where both Pre-Illinoian and Wisconsinan glacial deposits occur at the land surface." - Iowa Geological Survey

The uplands in the western half of this region cover glacial till from Pre-Illinoian glaciers that have been separated from their paleosols - which is ancient soil - due to erosion. On the contrary, the eastern half of the Northwest Iowa Plain are covered in tills are from younger glacial deposits. This area is called as the Sheldon Creek Formation, a drift from 20,000 - 30,000 years ago. The Sheldon Creek formation is one of the only things that connects Northwest Iowa Plains to the Wisconsinan glacial advances have drastically affected the landscapes of the Des Moines Lobe to the east. The Sheldon Creek drift also dates to the Wisconsinan glacial age, but was deposited during an earlier glacial episode. Radiocarbon dates that this older ice advance occurred 6,000 - 16,000 years earlier than the Des Moines Lobe drift (Iowa Geological Survey).

Click the buttons below to show or hide the Sheldon Creek Formation. Also, click on the areas to learn more.

In contrast to the Northwest Iowa Plains, the Paleozoic Plateau has very little glacial deposits, for it’s mainly comprised of rock outcroppings, woodlands, and bedrock. The plateau in Northeastern Iowa is an extremized version compared to the Northwest plains; its rugged terrain is deeply carved and its many valleys are deep and skinny, containing contain cool, fast-flowing streams. Most of the Paleozoic Plateau’s erosion happened during the Paleozoic age. Its landscape is composed mainly of bedrock, which is clearly evident in the upland areas. The land is also blanketed by a thin loess cover. While most of the land has little to no glacial drift, there are still a few isolated patches scattered around the landscape. The Paleozoic Plateau has excellent water drainage, as well as a karst topography. Therefore, the area is scattered with sinkholes, caves, and springs.

The Paleozoic Plateau has a lot of cliff-like layers of rock called Strata. A majority of these Paleozoic Strata contain rocks from ancient time periods, such Cambrian, Ordovician, Silurian, and Devonian age. These rocks were originally created by loads of sediment piling up when Iowa was submerged underwater, which was 300 - 550 million years ago. The most prominent of all the Strata ridges is the Silurian Escarpment. It is comprised of a tall, steep, shelf of rock that points towards the northwest. This continuous rock face follows an irregular path from the center of Fayette County to the southeastern part of Jackson County. The Silurian Escarpment's sudden drop of elevation marks off the southern and western borders of the Paleozoic Plateau. Off to the side of the Silurian Escarpment, are wooded bluffs that follows the rim of the Strata. These bluffs are cut off in the middle by several little, narrow, and steep gorges and ravines. These areas are home to moist, cool forest habitats that host unique, and sometimes rare ecosystems of plants and animals. Several of these habitats have been classified as protected areas, such as the Brush Creek Canyon, Mossy Glen, Bixby, and White Pine Hollow state preserves.

Bedrock, Strata, Caves, and Forests! Wow! It is clear that the Paleozoic Plateau has a lot of diversity in one area. As nineteenth-century geologist Samuel Calvin fittingly claimed, the Paleozoic Plateau is essentially like the "Switzerland of Iowa"!

Click around the map to find the elevation and the bedrock depth. If there are multiple overlapping entries, you will see a small arrow on the pop-up box, allowing you to move on to the next entry. Also click the black points to see the protected wildlife areas mentions above. Use the buttons below to toggle their visibility.

Next up is the Southern Iowa Drift Plain, which represents most of Iowa. This plain can be thought of like that old but wise grandpa that always invites himself over to the family reunion. Though he may not be the most interesting, lacking any cool features that makes him stand out, he is very wise. He has his whole life already planned out, and is in a stable position, unlike your crazy uncle who’s always getting into trouble. Just like this grandpa, the Southern Iowa Drift Plain is pretty typical, and has its whole region figured out, with developed drainage systems that keep it in place, unlike some other regions that are poorly drained.

 As a monotonous region, the view can stretch for long distance - only limited to how far as the next bend or hill in the road - without any elevation to provide a glimpse of the subtle, rolling landscape. The land reveals the level of the original land surface created by the most recent ice sheet. By observing the distance between hills and valleys can you see the amount of time and sediment that has been extracted in sporadic episodes due to changing soil stability. In the middle of gradual evolution, a wind blew cloak of loess, (the same loess that created the Loess Hills) which covered the surface of the plains in a blanket of sediment with varying thicknesses between 5 and 30 feet. Now dotted with minute farmlights and occasional head lights from scattered homes, the night displays a feeling of space, freedom and enclosure just as well as the broad daylight.

 The Southern Iowa Drift Plain is the biggest land feature of all the regions and the oldest by far. The glaciers that paved the land actually came hundreds of thousands of years before most glaciers in the northeast, thus granting it more time to mature and erode away all imperfections. It now lacks any geological monuments that signify the the fact that covered in a huge glacier, like moraines, kames, kettles, bogs and lakes; the only thing left of this stable plain of Iowa is the glacial till that covers bedrock below. Even though it doesn’t contain features like these, the drift plain has established a well connected drainage system over the years. Carved into the land, these drainage systems start off small, usually etched on hill slopes in the higher drainage network, with rills that give a distinctive look to the terrain. These small streams pave into a ravine, then into an annual creek, and finally to major valleys all-year-round streams and rivers.

Though it may not be the most fancy, the Southern Iowa Drift Plain makes up most of the typical, distinctive Iowa landscape. It is matured and sophisticated, balanced with little drainage systems and layers of loess and glacial till. An old staple region, this landscape brings a nice contrast to the rest of the state, and a strong sense of community.

Click the buttons below to toggle the comparison layers for the Southern Iowa Drift Plain. When on the waterways layer, zoom in to see the rivers. Click around to learn more about that particular area.

"Sweeping, outstretched landscapes span a large area of the northeastern quarter of Iowa. This relaxed, open topographic style is free of the strong expressions of glacier surges, silt-laden winds, or erosional sculpture that identify the Des Moines Lobe, the Loess Hills, and the Southern Iowa Drift Plain." - Iowa Geological Survey

Another land feature of Iowa is the Iowan surface, a more laid back and subtle region that contains "numerous clues to an elusive chapter of Iowa's glacial history." ( Jean C. Prior, n.d.) This landform region was originally a part of the hilly landscape of the Southern Iowa Drift Plain, before the Wisconsin Glacier age. Extreme erosion, as well as weathering, development of soil, and Loess deposition changed this. Similar erosion on Iowa’s watershed areas - which are areas of land where water drains to the same body of water. Unequal erosion in different areas created the step-like land formations that are visible in the watersheds. The most recent period of erosion of the Iowan Surface happened 16,500 - 21,000 years ago, during the coldest part of the Wisconsinan Glacial Period. During this time, the continental ice sheet expanded greatly in size, changing the land through erosion and cold-climate weathering. The Iowan Surface area could not withstand this extreme change, causing much of its land to be relocated elsewhere. This resulted in a land with varying elevations; the higher points of land with minimal erosion, with sharp contrast to the lower elevations which have experienced extreme erosion. The last glaciers to visit the Iowan Surface were Pre-Illinoian, giving the landform region a lasting break from glaciers to this day.

The organic-rich sediment in the Eastern Iowa Glacial deposits are a treasure trove of fossils of arctic and subarctic flora and fauna. These fossils include plants, insects (mostly beetles), small mammals, and gastropods (snails) that resemble the life in current day Northern Canada. This shows that Iowa was in tundra-like conditions around 17,000 years ago. Back then, Iowa’s climate was colder and wetter than it is today. The ice-free tundra areas of the upper Midwest experienced a lot of erosion, though the form of excessive freeze-thaw weathering, slope sheetwash, and powerful winds. These conditions and processes led way to the extremely eroded landscapes in northern Iowa, the area closest to the expanding glaciers. The land became slumped and washed down, because the conditions made it super unstable and worn down. Because of this, the Pre-Illinoian upland summits and divides became lower, and paleosols - such as Yarmouth-Sangamon and Late Sangamon - were removed from the landscape. This turbulent history has left its mark on the Iowan Surface, giving it its distinctive look.

Click the buttons below to toggle between the erosion, watershed areas, and land classification layers. Click on the legend button to view the legend. Click on an area to learn more. If multiple entries occur for the same area, a small arrow should appear on the pop-up box. Click it to see the other entry.

There are hundreds of streams and creeks scattered across Iowa. While they may seem meaningless - easy enough to pass with a mere skip - they play a huge on going role in Iowa’s erosion. These watersheds are what the Iowa Geological survey calls, “the most significant geological process presently at work on the Iowa landscape”. These drains help drain and transport excess water and sediment across the country, with most ending up in the Mississippi delta in the Gulf of Mexico. During the process of erosion, areas with a lot of these streams produced whole plains full of extra sediment called alluvium. The definition alluvium from Oxford Languages states that the word means, “a deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil.” That’s exactly what the surface of the Alluvial Plains are made of. This lowland has a thick layer of alluvium along with streams that sculpt the plain. These streams create valleys, flood plains, streams, oxbow lakes, terraces, and sand dunes.

To understand the journey of the sediment, picture the sediment like each individual is going on a commute. On your way to your destination, the Mississippi delta, you may run into traffic, like getting stuck in a pool or shoal (accumulation) of other sediment. It is also common for sediment to gradually undercut into a bank, eventually causing the material to fall into the stream. You would probably get caught in this road bumper along with other extra sediment and accumulate on the inner corners of the stream called Point Bar Deposits. If that wasn’t already enough to slow you down on your trip to the delta, you also take some time create some land features while your at it. Alluvial Fans are when flowing water, as small as rain water to a fast moving river, carve into a mountain, hill, or canyon and pick up particles. These particles get bashed up against the banks of the river and river sediment, eroding them, and creating more particles.

“Episodes of downcutting and sediment transport alternate with lengthy periods of sediment storage on both small and large scales and over short as well as long periods.” - Iowa Geological Survey 

When traveling on the creek highway, the water’s pace will not always act the same. When the flow is stronger, more heavy sediment gets transferred, but when it slows down, it allows deposition of coarser dirt, and only the finer grained particles of silt and clay can pass by. This alteration creates the unique structure of the Alluvial Plains, and shapes the rivers and streams into interesting figures.

Click the buttons below to switch between several comparison layers for the Missouri Alluvial Plains. Click the legend button to view the legend for the particular layer. When on the waterways layer, zoom in to see the rivers. Feel free to click around to learn more.

When the first settlers of Iowa set foot on Iowa, they weren’t greeted by rows and rows of corn like we are today. They were greeted by oceans of prairie grass. Before European settlement, the center of the United States was covered in three different kinds of prairie: shortgrass prairie, mixed prairie, and tallgrass prairie. These prairies originated 9 -10 thousand years ago after the retreat of Iowa’s most recent glaciers. Prairies thrived in mineral rich soil, which was created by glacial drift and parent material left over from the glaciers. Iowa had a lot left over from glaciers like the Des Moines Lobe, providing a home for Tallgrass Prairies. In fact, 85% of Iowa back then was covered in prairie. These prairies were home to several unique animals, including the iconic American Bison.

When Europeans first settled in prairie areas, they completely avoided it, not only because of their lack of experience in this type of land, but also afraid that the open land would leave them susceptible to many unfamiliar dangers. While they stuck to the cover of forests, Native Americans thrived in the prairies, depending on it for their daily survival. Eventually, the settlers started to investigate the prairies, and discovered the motherload that the grasses were hiding. Turns out, that the prairie grasses were hiding 14-16 inches of fertile soil, that was originally inaccessible because of sod. Farmers managed to plow through the sod to access the “black gold”. This soil led to healthy, bountiful crops.

Eventually, people forgot about the benefits that prairie grasses provided. They saw them as invasive, and started to clear them away. This created several problems. First of all, the deep roots of prairie grasses played a huge role in the soil. The deep roots held the soil together, enriched the soil, and absorbed farm wastewater that could pollute natural water sources. Once the prairie plants were removed, pollution became a huge issue, and the exposed soil eroded away, leaving only 6 - 8 inches left. Additionally, many of America’s unique prairie animals became either extinct or endangered. Nowadays, there is only 0.1% of prairie left in Iowa, occurring in scattered patches. Many of our plants animals are long gone, their memory written in books and inscribed on plaques honoring our long lost landscape.

Swipe the map on the left to compare the prairies of the US before human settlement to current day.

Key for the map on the left:

Light Green - Shortgrass Prairies

Middle Green - Mixed Prairies

Dark Green - Tallgrass Prairies

Key to the map to the right:

Bright Olive Green areas: Major current prairie remnants.

*Notice: the areas are generalized. These areas may not actually be accurate to this day.*

Luckily, we learned from the mistakes of our ancestors. The state and many other organizations have made an incentive towards recreating and preserving prairies. A small number of Iowa’s prairies are remnants, which are true natural prairies. Prairie remnants like hanging out in areas that are inaccessible for farming, such as areas that are too wet, rocky, or steep. The largest of these remnants are in the Loess Hills. Most of our prairies are actually manmade, either recreated or reconstructed, but recreating our long lost landscapes is not as easy as it seems. The soil condition, micro climate, and plant species diversity is extremely difficult to replicate. Additionally, collecting the native plant seeds is very hard, for many of them are very small. Some plant seeds are so small, that 100,000 seeds make up an ounce!

Even if we do manage to create artificial prairies on a large scale, they cannot replicate the exact natural beauty and biodiversity of our remnant prairies. For instance, most prairie remnants have around 100 different species of plants; at its best, prairie remnants can have up to 300 different species of plants. Manmade prairies have between 20-100 plant species. Additionally, our remnant prairies don’t have the same diversity of animal species. While we can bring back prairies, they won’t bring back all the animals lost to our rash actions. Nevertheless, both remnants and artificial prairies provide refuge to countless animals of all sorts, such as mammals, birds, insects, reptiles, and pollinators. Both prairies and animals benefit each other, as well as strengthening Iowa’s biodiversity. It’s a win-win for us, and nature.

Iowa has given us everything we know and see around us today. Look around. Our communities thrive because of Iowa rich geological past. Our farms - the one thing that let to our colonization in Iowa - were grown in prairie soil. We owe it to prairies for our economy and communities. Bringing back the lost landscape of Iowa is the least we can do to give back to our home.

Click around the points on the map to learn more about 39 of the prairie preserves in Iowa. You can also click the location button to find out which areas are near you!

Key to Map:

White Flags: 0-99 acres of prairie

Orange Flags: 100-499 acres of prairie

Blue Flags: 500+ acres of prairie

“Wilderness is the raw material out of which people have hammered the artifact of civilization.” - Henry David Thoreau

 Iowa has a rich long lasting culture and landscapes that positively impact our economy. Even our communities development is based on the environment. We depend on Iowa’s soil, climate and even the gently rolling landscape with thriving rivers and streams. Just like natural communities - a group of plants and animals living under the same environment - the principles that strengthen human communities both rely on interaction and interdependence. We create societies and niches to take advantage of the environment. After all, Iowa is an agricultural state because of its environment. The state was perfect for native Americans to farm, and though it took some getting used to due to their experience in the Appalachian, the early European settlers managed to skillfully craft the land. Modern day towns grew up around farms, grain elevators, railroads, and industrial businesses connected to agriculture. Even in newer urban areas now, we still have strong ties to our past.

As a result of this, it directly impacts our economy. In 2018, Iowa created about $27.5 billion in agriculture, with corn, hogs, and soybeans being the most valuable products. Additionally, 10.2% of total state GDP was attributed the value of Iowa’s agricultural production and processing industries. Some this money created by these industries end up being repurposed within the local economy, bringing more value to the table through “multiplier effects” (University of Arkansas, n.d.) So essentially, all of our money, communities, history, and culture circles back to the geographical features of Iowa.

As you can see, the map to the right is a simple satellite map showing Iowa's natural beauty. But a lot is hiding within those green expanses. Click the buttons below to learn more about human advances in Iowa, from where the Urban areas are, to the croplands. Zoom in to get more detailed and specific information for certain regions. Use the search button to locate places of your choice, and find out more about it. You can even click the location button to find out about more your own location! Click the white legend button to learn more about the symbols on the map.