Land Between Two Rivers; 102-Is; Des Moines Part 2

What. A. The following program is made possible through a grant from the Kennedy Lindstrom foundation incorporated a charitable trust Mason City Iowa. During our first program we explored the life and physical history of the land between two rivers five billion years fill the void of four distinct geological arrows. What we now call Iowa was molded by volcanoes and oceans glaciers followed and the Des Moines River was formed as the glaciers receded. Men emerged first as a hunter than a farmer. He left his mark.

Today archaeologists search for the ancient signs of man along the banks of the Des Moines River. Life abounds here as it does near Lake Red Rock a manmade extension of the Des Moines River. Birds like the American bald eagle the eastern Bluebird the woodcock and the blue heron make it their temporary home. Today more on the Des Moines River. This is. The Des Moines has seen its share of changes. Yet life still abounds in this valley building once again long past. We see that it has always been so. As the Des Moines River. Flows in its south easterly course across across south central Iowa we find exposed along the sides of its

Valley. Rocks of Pennsylvania New Age and these rock units cover a large part of the south central part of the state. And there are the rocks in which I was called deposits are found. This is a fascinating fossil. Impression of the bark of a tree that lived during Pennsylvania time in a coastal or tidal area in which there was a large amount of vegetation accumulating in low swampy environments environments which later gave us the coal deposits that we have in our state. This is the bark of a scaled tree a tree that geologists refer to as one of the more common Pennsylvanian plant fossils and one exposed here was just beautiful preservation you can see very clearly the scale pattern of the bark of this particular tree specimen. Yeah we just have reconstructed

the environments that probably contributed to these plants. And. In looking at diorama as that have been made of what the Pennsylvanian coal swamps look like we'll notice that they had an almost tropical appearance to them very large ornate tree just just very tropical in their appearance. And. Keep in mind that during Pennsylvanian time some 250 million years ago the North American continent and Iowa were not in their present position on the Earth's surface today for example or about 40 degrees north latitude. But during that period of time the. Vegetation the trees grew. From which these fossils were made Iowa was much closer to the equator. There is further evidence of Iowa's tropical plants. Once this land was covered by shallow sea it was home to a wide variety of creatures.

Now extinct. Now if you look closely at these fossils you'll see that there they are very different from the plant fossils that we were looking at just over the ridge from here. And these fossils are Mississippian in age and some of these even resemble the sea shell clam like shells and gastropods or snail like shells that you might find along the sea shore today so these are clearly Marine referring to these fossils as the Pella fauna indicates that there's a wide variety of materials here. And that's certainly the case for example. This is a fine little horn coral a solitary coral one of the individual fossils that's found here in the strip mining area. A very nice bracket pod. There are numerous bracket pot examples here. This is a type known as a spare for it has

kind of a wing prong coming off the sides of the shell and then lastly a little fossil that we refer to as a bra is one of the little branching form here. It's really quite remarkable to find such a diversity of fossil forms and it's really even more exciting to come to a place like this and to realize that each rock that you break open in each fossil that you look at is something that no one else has ever seen before and that you're getting your first look at something that was alive perhaps 200 or 300 million years ago. Jean Pryor mentioned how two hundred fifty million years of time processed an ancient swamp life into coal. But modern iron ones used to produce energy. There are other products of Iowa's geologic past serving the needs of the present shale strip mines. In this setting we're standing in the midst of a strip mine a mine

of shales that are being utilized in the manufacture of brick and tile and Tomoya is one of the major centers you know of for brick and tile manufacture. It's also interesting to realize that though we're using these materials today the fact that the shells are here in such abundance dates from the Pennsylvania period of geologic time a time when the site where we're standing now was actually a sub tropical to tropical sea or shallow marine environment where we had a near coastal environment quiet water where the very fine particles of Clay could settle out in those fine particles accumulated in in great thicknesses and were eventually converted to the shale deposits that we see here today. Sand is one of my was naturally occurring resources that we find

principally associated with the state's river valleys. The Des Moines River Valley here in the background shows us that resource very clearly. Not only is the flood plain area shared with agricultural crops such as this cornfield in the foreground but in the distance we see the workings of a sand and gravel operation. This is an area near a time when the sand that is being taken from this sand pad was laid down thousands of years ago as the river. Flowed past this area probably carrying a lot more water and and sand material than it does today. These sand deposits were probably first carried by the glacier in the in the northern part of the state. From here it's trucked out to several different places for use possibly for the fine sand goes into plaster manufacture the coarser aggregate for highway maintenance and construction. And some also take into already mix plants for

making concrete. It is natural to find sand along Iowa's rivers the streets geological past has left some surprises here north of nearly a hundred forty feet above the bottom like sand dune. Road. Looking beneath the grassy covered. There are very sizable deposits fine grain sand occurring. On this up one position. This is blow sand or sand material that has been brought to this up one area by the wind having scoured the flood plain areas down in the river valley and Reed you positing the sand up here

perhaps several thousand years ago the sandy posits are thick enough to have actually affected the terrain the appearance of the landscape and looking off in the distance we can see the irregularity of the terrain. The low mounted hills that are very characteristic of sand dune topography the dunes here are not too active. They are being anchored down quite securely by a good vegetative cover of grasses and oak trees. Past a time when the river leaves this area of sand dunes gravel pits shale mines and coal beds flowing into an area where the more recent history of what is written in the architecture of towns like Benton support and Bonaparte. It was a time when the river powered mills that crushed grain fabric and sawed wood. A period when steamboats braved the shallow muddy waters of the Des Moines. The first known demoing steamer was the hero in 1837. Nature

however was annoyingly uncooperative. Excepting the occasional good years the steamboat Charles Rogers actually reached Fort Dodge in 1859. Steamboating fairly limped along for most of its 30 year history. This was not for lack of desire on the part of all concerned including the federal government. There was some improvements were made. Des Moines River navigation remained elusive steamboating on the demoing ran aground in the 1860s with the spread of railroads and civil war and Iowans finally lost interest. But there was still a great deal of interest in what the state had to offer a future industry. Members of the newly created Geological Survey traveled the state. Mapping and recording the treasures of the land between two rivers such as the Horseshoe Bend in the Des Moines River New York. We're looking at Alyssa graph that was drawn and prepared in

1868 a view that looks very much today like it did well over 100 years ago when the scene was first sketched by a man named arrestees St. John who at that time was Assistant State's geologist with the I would say a logical survey. At that time cameras were not extensively used in the field and the early geologist had to depend on their own skills as an artist in order to document scenes that they saw in the landscape that they regard as important for the preparation of their geological reports. The remarkable thing in looking at this scene again with the passage of this amount of time and seeing so little change having taken place is largely due to the fact that the wooded treeline blow off the very picturesque setting that we see across the river has been left almost the way it was and the primary reason for this has been the establishment of that area over there as part of Lacey

State Park. These green bluffs have changed little for hundreds perhaps thousands of years. It is one of those now rare places where you can imagine and I was long gone. We're sitting here on the bank of the Des Moines River very close to its mouth

whenever a major river cuts through the through a landform in this case the Southern I would drift plane. It has great biological implications. It creates a corridor through the landform that is very important for the migration of plants as well as animals. There are certain species of trees and other plants which are in Iowa strictly because of the influence of the Des Moines River. The second more tree is native in Southeast United States and probably 100 or so years ago we very likely did not have any any sycamores in the state since that time they've been utilizing the this corridor this nice green corridor that is on both sides of the Des Moines River. And before that the loneliness if you ever use this corridor to migrate very slowly over decades and decades

into southeast and now they've reached the center part of the state. The leak of the sycamore tree is huge. Look at this one fully as large as a dinner plate. This is the largest leaf of any native tree that we have. The sycamore tree itself that we're standing here beside is and beside it is a magnificent tree growing two in the center of its range heights of over well over 100 feet. And I would they probably get to 70 or 80 feet because they're still relatively young trees but they are biologically important to the to the animals of the state birds nest in the very tops of the trees. Hawks will nest in them Owls Nest in the cavities for bears will nest in the use them is then trees so we cannot overemphasize this the importance of this tree as a biological entity. The biological Nish provided by the sycamore tree is just part of a

larger natural system along the Des Moines River. We're walking through a floodplain of the Des Moines River in southeast Iowa and one of our major state parks these flood plains are formed over the centuries by the periodic flooding of the the Wind River and the trees that are here. The placer here have learned to adapt to the periodic flooding. They're very flood tolerant species the floodplain forest forms a buffer between the upland in the and the river keeping the sediment load low. It forms a stable river bank to keep the banks from eroding and we have a complex of animals that exist in these flood plain habitats that we simply don't find anyplace else. And also it's a very disturbing them. Over the years especially in the last 50 60 years the flood plain forest flood plain community has become scarce because of various aspects of

this is very rich farm ground so where people can clear them and find them they do this some of the timbered trees here are of commercial value so people have allowed them to be logged and sold the floodplain community is one of our most one of our scarcest communities we have in the state. And because of the scarcity it is one of our most priceless. Priceless Jim Lacey State Park stands like an emerald Oasis along the Des Moines nearby. Some very real gems can be found by the alert rock. In southeastern Iowa the Des Moines River has cut down through Mississippi and age rock formations one of these rock formations in particular. The war starts shale

yields a very interesting type of rock to geologists and to rock homes. This rock is called a geode. And here in the creek bed of this small tributary to the Des Moines River we find a beautiful exposure of GEOS seeing very clearly how they occur in their natural setting lining the street with a stream bed occur as discrete and rounded little nodules along this particular scene in the shale southeastern Iowa is a very well-known Geode occurrences in the valley of the Des Moines and its tributaries are probably one of the prime collecting localities for this particular rock in the United States. Geode are also Iowa State run. On the outside they're very ordinary grounded looking exterior but the real surprise and real enjoyment in Geode hunting comes when you begin to work at these with a hammer and chisel and

find what beautiful things actually lie inside these very ordinary looking rock. Yeah this is a nice. Surprise of opening them up and having a chance to see for the first time the beautiful crystalline cavity that we find. On the inside. Shields are one of the puzzles that geologists have to deal with. We know that they are found within the shales and limestone is here in southeastern Iowa in the Mississippian age rocks and they were not something that formed at the time that the rocks themselves were formed they were something that happened later. We had to have some kind of an open space a cavity within the rock so one of the theories is that perhaps this space was once occupied by a sea

drilling animal or a plant like form that grew on the sea floor and occupied this space for some period of time. The space left by that particular form of Marine Life is what then provided the opening for the later crystal growth to take place. The ground moving through these rock layers was highly charged with with mineral material courts and calcite in particular are the more common minerals that we find forming the insides of shields. And it was this migration of highly charged groundwater that geologists feel was the source of the minerals that now line these geode. A. The power of moving water carve a valley like a

creator of geo and subterranean minor stars k a tunnel through Burlington limestone near the town of the same name. Caves are. Formed very slowly through geological time from any movement of groundwater entering cracks and fractures in the limestone gradually dissolving the calcium carbonate into solution and slowly through time and large in those cracks and fractures into caves in caring systems. One of the primary characteristics of the Burlington limestone is its extremely fossiliferous nature. And here in Star's cave which is developed in the very link to the limestone we can see in the roof of the cave almost solid fossil debris. The limestone itself is almost entirely composed of fragments of fossil material primarily crying noise which is what the Burlington is

especially well known for crying noise from this formation have been collected and are known worldwide for their outstanding beauty and in detail. The story of IO was written in earth and stone and life. Before leaving the Des Moines Valley one final look at some of the rivers few remaining forests. We're standing here in the middle of an area known as shimmy state forest. It's owned by the state of Iowa managed by the state Conservation Commission and it is the naming of this area that the state has chosen to memorialize the name of almost shimming who is a professor and for many years at the University of Iowa who collected extensively and whose records about her only touch with the true native Iowa. She makes State Forest is composed of many sections stretching from near the mouth of the Des Moines

River up to Lacey. And even though this is a rather succession malaria a fairly young forest it is still a very important biological area because this is where almost every bird migrates into central Iowa has to pass through this area on its way up there. And so probably most of the thrushes the sparrows the warblers have to pass through here as they migrate follow the Des Moines River up to the northern part of the state and we cannot overemphasize the importance of areas like this for stopover places for birds can spend the evening and rest and feed before the following day's migration. The Des Moines ends flowing into the Mississippi but the rivers flow through the mind continues. You may forget specifics. Hopefully some thoughts will remain.

The impression of time while the robins glorious spring song makes the world seem new. This scene is so full of hope and promise. It's five billion years old. Humanity's part in this scheme is nothing compared to the land's age. But the human touch upon this land rivals even the awesome effects of time. The perspective of utilisation it is clear that Iowans will utilize their natural heritage. The critical question is how. The prudent dancer will recognize the land's value beyond just the agricultural or industrial. It will consider the wealth of knowledge stored within our natural heritage mysteries of stone and earth. The wisdom of those who lived in harmony with the land and secrets yet hidden in broadleaf second Moore's or the stately soaring of eagles. It will acknowledge

nature's healing effect on tired spirits in a frantic age and perhaps most important it will accept that humanity's very survival is inescapably tied to our fragile environment to fully utilize our natural heritage then we must first preserve it. One final thought. The land between two rivers. Five billion years of living masterpieces. Is not ours alone. We share it with all living things. We share it with our children and our children's children. Why.