Monday, October 26, 2015

A Step Back in Time at Yellow Banks Park

American Indian influence has been discovered throughout our park system here in Polk County but none as evident as in Yellow Banks Park. Nestled within the very southeast corner of the county lies this 557-acre recreation area overlooking the Des Moines River. Named for the rich yellow loess soil deposited along the banks, this river valley landscape was home to several native cultures such as Paleo-Indians and the Oneota. Evidence of their presence along the river points to a productive area capable of sustaining populations since the retreat of the last glacier that covered portions of Iowa as recently as 10,000 - 13,000 years ago.

What makes Yellow Banks Park such a unique piece of land is the convergence of various landscapes in this one area which sits right on the cusp between the Southern Iowa Drift Plain and the Des Moines Lobe above the Des Moines River Valley (carved out by glacial meltwater). The park derives its name from the yellow loess soils that have accumulated at this site since the Illinoian glaciation.The park represents a rather dissected landscape ranging from high-dry loess landscape down into deep, moist valleys. This deeply incised river valley landscape was a prime location for early native people who were attracted to the biologically productive bluffland features which provided the natural resources required by native deep wood river and prairie savanna communities alike. From this place arose a civilization from which we are able to catch glimpses of through archaeological finds. 

When the park was first obtained by Polk County Conservation in 1980, the state archaeologist was hired to survey Yellow Banks for artifacts and significant areas. What was found of significance were Native American burial mounds scattered throughout the area. Only one mound remains intact as several mounds were removed when the Red Rock Reservoir was formed and a railway line was moved up on the bluff. Since then, more deliberate care has gone into managing this area when projects are planned out. 

Many artifacts have been unearthed at Yellow Banks, lending to its rich history of the native populations that lived along the banks. Remains of people as well as their lifestyles have been found. A pottery shard was found in a gully along the Des Moines River that was traced back to Correctionville in Northwest Iowa, and identified as trailwear. Unearthed trade goods such as obsidian traced back to Yellowstone and shells from the Gulf of Mexico imply that an extensive trade network had occurred right along the Des Moines River at Yellow Banks. Various projectile points for hunting and stoneware for cutting, grinding, chopping and skinning purposes have also been found in abundance at Yellow Banks Park. Even settlement-era artifacts such as a bullet mold for a musket provide insight to past activities in the area throughout history. The area had clearly been suitable to sustain culture and trade throughout 10,000 years of human history. Yellow Banks' rich, fertile river valley is what lies at the foundation of the area’s success. 

Indigenous People of Iowa Timeline 


Paleo-Indians (9,500-7,500 BC)
Clovis Projectile Point
Paleo-Indians were wandering buffalo hunters. They followed big game through a cool, wet, forested post-glacial landscape. These people left behind leaf-shaped spear points, stone knives, and hide scrapers. These tools were used in hunting, butchering game, and dressing hides. 

Archaic-Indians (7,500-500 BC)
Butterfly Banner Stone
The Archaic people were hunters and gatherers. They hunted buffalo and smaller game animals. In wooded river valleys the archaic people collected hickory nuts and hackberries. Lamb’s quarters, sunflower, and marsh elder seeds were also gathered. Grinding stones for processing seeds and nuts have been found in Yellow Banks Park. They also manufactured stone axes for cutting trees and  woodworking. The Archaic people invented the atlatl or spear thrower. It was a two foot long stick with a hook on the end. The atlatl helped hunters throw their spear harder and further. A very rare banner stone or counter weight for an atlatl was found in the park. 

Woodland-Indian (500 B.C. – 1000 A.D.)
Stone Knife - cutting and skinning
The Woodland people were hunters, gathers, and gardeners. In small garden plots they grew sunflowers, pigweed, goosefoot, and marsh elder for their edible seeds. Later, the woodland people grew corn, beans, squash and tobacco. These crops were imports from Mexico.
Woodland hunters used spear points with corner notching at the base. About 400 AD the bow and arrow was developed. Hunters began killing game with arrows tipped with one inch long triangle points.

The Woodland people made the first pottery in this area. Pots were made with clay that had grit or sand added to it as a tempering agent. A tempering agent helps to keep pottery from cracking while it is air drying. Later the pots were “fired” in a wood fire. The outside of the pots were often decorated with cord markings. 

Indian mounds were built by the Woodland people. These large earth monuments were built on bluff tops overlooking a major river. They were often circular in shape. Human burials, stone tools, and pottery were often placed in Indian mounds.  

Oneota (AD 1050-1700)
Hide Scraper
The Oneota people spent their time hunting, fishing, plant collecting and farming. They lived in villages of bark covered longhouses located along major rivers. In small fields on the floodplain the Oneota grew native varieties of corn, beans, squash, and sunflowers. After the crops were started and hoed a few times, the people would leave on seasonal buffalo hunts. They also collected edible wild plants. The Oneota people left behind some characteristic artifacts such as celts or grooveless axes, clay pots made with ground clam shell tempering, and one-inch triangular arrow points. Grinding slabs for processing corn have also been found. This group of people lived in Iowa into the historic period where they were known as the Ioway Indians.

Generations of indigenous peoples lived, died and shaped our landscape right here in Iowa. Their ways of life are still reflected in remnant village and burial sites scattered across Polk County and the river valleys of Iowa.  We can learn a great deal about ourselves and how we relate to where we live by respecting and studying those who have come before us.

Ready to learn more? 

Join Polk County Conservation naturalists on Saturday, November 14th at Yellow Banks Park (meet in the tent camping area) from 1:00 - 3:00 p.m. for Native American History Day.  

Get hands on experience constructing a tipi and try your hand at throwing an atlatl. Don’t know what and atlatl is? Join us and find out. Authentic artifacts collected from the area and rarely seen by the public will be interpreted. The artifacts span over twelve thousand years of history and represent four different cultures. We’ll also take a short hike to the last remaining burial mound in the park. This event is free and all ages are welcomed. 

Monday, September 28, 2015

Bats, Spiders and Snakes - Oh My!

They creep and crawl! They slither and slide! They swoop and dive! It's the creatures that own the night and fill our slumber with the things of nightmares. Peruse the shelves of any Halloween department this month and you will be provided ample opportunity to adorn your home in terrifying paper and plastic versions of these haunting critters.

Wait, wait, wait...

What about a world infested with mice, mosquitoes and other insects? There are an estimated 10 quintillion (that's 1 followed by 19 zeros) individual insects roaming this planet at any given time. This number represents nearly 80% of the world's species. According to Encyclopedia Smithsonian, there are more than 200 million insects per human on Earth. And nearly 21 million homes in the U.S. are invaded each year by the pitter-patter of scampering mouse feet.  Enter in bats, spiders and even snakes. Unhuggable as they are, these animals actually provide a significant ecological benefit to the environment - and us! - by keeping these already mind boggling numbers in balance. Imagine what a truly creepy world it would be without the crawling, slithering, swooping ones to keep those numbers in check!
Courtesy of

Bats have the tendency to conjure up images of blood sucking, rabies infested flying rodents that blindly dip and dive and otherwise wreck havoc on your late night backyard festivities. Myth surrounds this animal so let's start by separating a few facts from fiction for bats and other creepy crawlers.

While rabies is most notorious in bats, the prevalence is relatively low. While caution should always be exercised, instant condemnation of these critters goes undeserved in the vast majority of situations. According to the World Health Organization, 99% of human cases are caused by domestic dog bites.
While animals such as bats do in fact carry diseases such as rabies, the chances of contracting such an illness is low with 1-3 cases reported from a variety of animal bites each year in the United States. Less than one-half of one percent of bats carry rabies. Death by mosquito, on the other hand, occurs in nearly 1 million people each year. In fact, mosquitoes are touted as the most deadly creature to mankind as carries of disease. And the average bat consumes 3,000 insects in one night!

Bats also have a bad rap for attraction to people's hair. Could this be due to their blindness? We have all heard the "blind as a bat" simile and while bats do have poor eyesight, they are not blind. Bats "see" with their ears through the use of echolocation. Using high-pitched sound waves directed out ahead of them, bats utilize the echoes that bounce of objects and relay back sight information. So when it appears that bats may be swooping down at your head looking for a place to nest, what a bat is most likely interested in are the insects flying around those lovely locks of hair!

The average spider consumes 2,000 insects each year (National Geographic). There are about 3,000 different kinds of spiders in the United States. Most species are harmless and rarely bite people. All spiders are venomous, but only a few have strong enough fangs and powerful enough venom to harm humans. A spider’s venom helps them kill or subdue their prey. Some people may be allergic to spider venom but only a few species of spiders are known to produce bites that are harmful to humans. That venom helps spiders consume nearly 2,000 insects per year.

 Even snakes help to control pest populations, especially common snakes here in Iowa. Non-constricting, non-venomous snakes will typically make a meal out of insects and small rodents. Garter snakes are the most common genus of snakes in North America, living in grasslands, woodlands, marshes and your backyard or garden. These little guys are doing your yard some good by eating a variety of critters including insects, mice and voles. Other species such as bullsnakes specifically require larger prey and are quite beneficial in controlling the damaging effects of rodent overpopulation.

So the next time you come across one of these critters, avoid the urge to swat, stomp, or otherwise smoosh out of existence one of nature's most effective (and free!) forms of pest control!

Wednesday, August 26, 2015

Branch Out into the Hidden World of Trees

Oak Grove at Fort Des Moines Park

Q. What do pears, car wax, and anticancer treatments have in common?  
A. Trees - they all come from trees!

Thousands of products and goods we use every day begin as trees growing right outside our door. Totaling 25% of all living plants, trees are estimated to include 100,000 species! These 100,000 species also provide habitat and food sources for wildlife, comfort and aesthetically pleasing additions to our landscape. But the inherent value of a tree is not in the products we derive from them nor the beauty they provide. The value is in the behind-the-scenes things unfolding the moment roots take hold and a seedling bursts forth from the soil.

Ecosystem services are those services/processes either directly or indirectly provided to humans by the natural environment at no cost. Categories of ecosystem services are generally broken down into 5 categories:

1) Production of Goods
Trees: fuels, food, medicines, waxes, timber

2) Regeneration Services
Trees: air purification

3) Stabilizing Services
Trees: reduce water runoff

4) Life Fullfillment
Trees: beauty, recreation, spiritual inspiration

5) Preservation of Options
Trees: future supply of goods, services and discoveries for the future

We are all directly provided for in the Production department. We can look throughout our home, school or workplace to see how vital trees are in our day-to-day lives. But what about the other categories that we may not automatically take into consideration?

Let's take a closer look outside our front window at what is going on within a tree. The air around us is purified by trees through absorption of certain gases and pollutants. The cool thing about trees and other green plants is the process of photosynthesis -  trees take up carbon dioxide as a necessary part of making their own sugars for food/energy and, in the process, release oxygen as a byproduct for us to breathe. Bonus - carbon dioxide is one of the 6 culprits responsible for accelerated climate change. One tree can absorb nearly 48 pounds of carbon dioxide each year; and a 40 year old tree has sequestered, or put into long term storage, nearly 1 ton of the stuff...for free!

Trees also can help stabilize the microclimate of your property. Shade provided by trees helps lower the temperature, especially in urban areas. These front lawn inhabitants help to slow down water evaporation from the ground which also helps in temperature regulation. Even the climate inside our homes can benefit from trees. Costs associated with air-conditioning and heating are reduced by up to 40% when shade trees are planted within 30 feet of homes or other buildings! Conifer windbreaks along the north and west sides of your property also help to reduce overall energy costs.

In Iowa, we hear quite a bit about water quality and soil vitality. What do trees have to do with this?! Trees filter water pollutants, slow runoff and help control stormwater in towns and cities. The hardy root system of trees also help to anchor in soil, preventing erosion while maintaining the integrity of and replenishing Iowa's precious topsoil layer - a vital resource we are losing at a conservative rate of 5 tons per acre per year on crop fields.

Plant some shade today!

So let's do our part from home by preserving the ground on which we live! Residential customers of MidAmerican Energy Company can reduce future energy use, landscape their homes and green up their communities this fall through the Plant Some Shade® program. Plant Some Shade enables MidAmerican Energy’s residential customers to purchase up to two landscaping trees for $30 each. Trees are sold on a preordered, first-come, first-served basis. Pick up will be available on October 10th from 8:30 - 11:00 a.m. in the south parking lot of the Hoover State Office Building.  For ordering information, click here

Available trees. Click on tree names to find out more about a species.
(Dimensions below indicate size at maturity)