Fly Over Country

Our bird populations have seasonal rounds. Most of the songbirds like robins and meadowlarks have left. Now the main birds that we see are either passing through or are the ones that stay around all winter.

Bald eagles stay year round. Here’s a photo of one that was recently flying around the ‘Eagle Tree”. When we first moved back to the Farm twenty years ago, an eagle or a coyote sighting was rare and exciting. A friend who is a naturalist confirmed that. He says the first bald eagle that he saw in Rock County was in 2008. Now both critters are more common and we’re glad for it. Coyotes get blamed for killing calves and consequently there’s a hunting season for them. At one time people shot eagles to protect chickens. Now, the bald eagles are protected. Maybe someday we’ll recognize that both eagles and coyotes are only a minimal threat to domestic animals. Both species are mainly scavengers rather than hunters and they’re doing an important service that’s an integral part of a robust prairie ecosystem.

These pictures are from a blog post last spring. They’re taken in the pond and wetland complex that are located in the abandoned meander (the “oxbow”). The herons have left for the fall, but the geese are still around. In the spring they come up the Creek from the Rock River to build nests. In the fall they periodically come and go. These local homebodies fly low and are probably wintering nearby. In contrast, the high-flying, v-formations are long distance migrators headed south.

During the unseasonably warm weather several weeks ago, I heard a really distinctive birdcall. I think that it may have been sand hill cranes because they sounded like online examples that I found. I never did see them but I assume that they were flying high and fast. I don’t think that I’ve ever heard them here before. Isn’t the sand hill migration route usually farther west so they can hit the Nebraska Sand Hills for a rest stop?

Owls are one of the birds that are here all year, lingering through the winter. We usually hear them before sunrise and after sunset, but we don’t often see them during the daylight. After the snow last week I did see one up east of the homesteaders’ house (the “Greats’ House”). Maybe this hole is an owl house? We also have crows, starlings, flickers, blue jays, hawks, and sparrows that stay all winter.

Margret is a better photographer than I am. Here she is taking a picture of the pair of bald eagles that we saw this morning. You may have seen it on her Face Book post. She is recording the unique opportunity, but I first saw them when I stepped outside on the porch. I was following the lead of one of my nephews who once told me, “If you can’t pee off your porch, the neighbors are too close.”

Bald eagles are the symbol of the United States of America. They are also spiritual guides for Native Americans. And, they are icons for a healthy prairie. I’m grateful for the privilege of living on the prairie. 

I hope that you will all enjoy a safe holiday this week celebrating the joys of family, food, and gratitude.

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Nature Will Not Be Denied

This time of year, plants and animals seem to loosen their grip on the Farm. Corn and soybeans have been harvested, cattle have been moved off the pasture paddocks, leaves have fallen off the trees, and grass is brown. But, we know that after winter, plant and animals will reassert their control. And, in the storage sheds where there’s little traffic or activity, both plants and animals invade during all the seasons of the year.

Earlier in the fall, the “varmints” started looking for a place to spend the winter. Actually, they’re pretty busy year round. We have skunks, woodchucks, raccoons, and possums dig under woodpiles and burrow into sheds all the time. In some cases it doesn’t matter and we can live with them. But, other times they can be pretty intrusive and something needs to be done. This photo shows a skunk in a live trap earlier this fall in one of the cluttered sheds. This approach is only a partial solution, however. The live trap helps my aim when the varmint is killed, but in this case it took several weeks for the smell to clear out of the shed. The whole process works better outside of a confined space.

As a part of our long-term effort to downsize, we’ve been sorting and cleaning the storage sheds. We’ve still got a lot to do, as you can see from the skunk picture and from this photo. But, Nature is resilient and this bean plant is growing inside a shed without much light or water. It’s done this for several years and it’s kinda scary because the plant is so pale and so tough. How can it grow without light or water? Maybe it’s got some vampire genes that make it comfortable in the dark?

One of the things that we’ve hauled out of the sheds, is an old canvas used to cover feed wagons that stored ground ear corn back in the day. It’ll eventually end up on the burn pile, but I’m using it to cover and kill weeds until then. I spread the canvas out over a patch of nettles after burning and mowing. It was supposed to work like mulch and suppress the weeds. But, the holes let in light and moisture so the nettles grew right up through those windows. I guess it worked about as successfully as shooting the skunk inside the storage shed!

Buildings come and buildings go. Our house is the newest building on the Farm and it’s more than twenty years old. The “Great’s House” is where the homesteading family, their children, grandchildren, and great grandchildren have all lived. The “new” addition to the Great’s House is more than one hundred years old. Between the oldest and the newest buildings, there’ve been some changes carried out by humans. But, Nature is the constant driver of change.

The vine in these photos somehow came up behind the siding on the Greats’ House and then emerged to grow and entwine in a more familiar way. Consequently, it looks like it grew right out of the wall of the porch on the southwest corner of the house. You can tell by all of the green that this picture was taken earlier in the year. Nature will not be denied.

As the generations change, the buildings also need to change. Horse barns are replaced by tractor sheds. After the Holidays, I’m planning to do a series of weekly posts that document those changes in a tour of both the old and the new buildings around the farmyard.

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Buried Sand Aquifer

The last couple of posts have described fractured clay till and an overlying terrace gravel that store groundwater in the Creek pasture. Both aquifers “leak” out onto the ground surface to form springs. However, this post is about a layer of sand and gravel buried under the floodplain of the Creek. When water in the channel is high, water goes into the aquifer. But when the channel water is low, the groundwater from the buried sand flows out into the channel.

The buried sand isn’t a layer of uniform thickness and doesn’t seem to be present everywhere. This map shows the location of boulders (marked with red Bs) in the Creek channel. In these places, the buried sand is mainly missing. In contrast, the sand is locally exposed above the water at several places (shown by the black Xs). The dashed lines outline the extent of the aquifer and the blue arrow indicates a place where groundwater from the buried sand flows out into the oxbow which is an abandoned channel segment. The numbers are the locations of the next four photos.

This pair of photos illustrate the variable thickness of the sand layer. The top of the light colored sand is fairly close to the surface of the water in the Creek near the bridge. Similarly, the sand layer at the left of the second photo is also close to the water. However to the right, the sand is thicker and the top of the sand layer is much higher above the water. The buried bottom of the sand layer is probably also at different depths, so the thickness of the layer is highly variable.

Boulders are found in the channel where the sand layer is totally missing. The staff in this photo is about five feet long, so this is a big guy boulder. Not too far away, the sand is present and the top is easy to see under the tan stream deposits with dark soil development at the top near the grass. The red arrow points to an area where the sand is stained orange by groundwater movement near the base of the layer. So, we can see both the top and the bottom of the buried layer; it’s not very thick here.

This past spring, the water level in the main channel was high enough to flood the oxbow. These two photos show the inlet into the wetland on the south side of the oxbow in the left photo and the connection between the main channel and the pond on the north side of the oxbow in right photo. At these high levels, surface water was probably flowing out into the aquifer, especially out of the pond which is closest to the buried sand layer. In this condition, the surface water is said to be “recharging” the buried aquifer.

As the year progressed, we ended up in drought conditions. The wetland totally dried up(left photo), but the pond only got smaller(right photo). It didn’t dry up completely because it was getting support from groundwater flowing out of the buried aquifer. The wetland on the other side of the oxbow did not get the benefits of the groundwater.

Eventually, even the pond dried up because the aquifer got drained. The photo on the left shows the pond just a few weeks ago. You can see the positions of the edge of the pond as a series of small steps that document the progressive shrinking of the pond. Without the input from the buried aquifer, the pond disappeared. However if the aquifer can be filled again (“recharged”), groundwater could again flow out into the pond. The photo on the right was taken several years ago after the pond had frozen over. The white lobes of ice that extend out from the high bank and onto the gray ice represent groundwater plumes frozen in place as groundwater leaked out of the storage area. So, back then the aquifer had excess water that could help to maintain the pond.

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Fractured Clay as Aquifer

This post is a continuation of our “walk about” exploring underground water stored in glacial deposits. The layers of sediment deposited by glacial melt water (“outwash”) and directly by the ice itself (“till”) have been mapped regionally in southwestern Minnesota by the Minnesota Geological Survey and I’ve used topographic maps, air photos, and soil maps to help locate these various deposits along the Creek. The idea that fractured clay till can act as an aquifer, is taken from work done by the South Dakota Geological Survey.

This cartoon is modified from last week’s post that introduced the ideas about underground water stored in aquifers on the Farm. The layer of fractured till is sandwiched between windblown silt and unfractured till in the hills and uplands that surround the Creek valley. Groundwater moves through fractured till and leaks out onto the surface as springs and seeps. The photo on the right is of a hill slope with newly planted cover crop. The first green whiskers of rye grass are growing in a linear pattern that probably reflects a particularly “leaky” fracture.

This fall photo shows a band of dark green vegetation that is probably getting help from groundwater that’s seeping out of the hill. It’s been a dry fall so the watered grass is particularly conspicuous. A similar band of differences in vegetation could be seen on this hillside earlier in the summer.

Similarly, the landslide behind our house is now marked by dark green vegetation that gets groundwater from the fractured clay till in the hill. The dry weather this fall gives brown grass for a contrast. Back in June there was actually standing water in the low spots between the landslide blocks. Now there’s less groundwater seeping out onto the surface.

The drought this fall has reduced the amount of water stored in the fractured till aquifers. Clay hill slopes like the photo on the left, that had active seeps last year now this fall are bare and dry as shown in the photo on the right. Actually, the springs were sill active this past summer, but now everything has dried up.

These near-surface aquifers like fractured clay till and like the terrace outwash described last week are easier to visualize and we can actually see the results of them leaking water out onto the land surface. In contrast, the outwash sand and gravel buried under the Creek’s floodplain are more subtle and open to interpretation. We’ll tackle that buried aquifer in next week’s post.

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Underground Water Along the Creek

In 2018 and 2019 we had record total rainfalls, but this year it’s been dry. That gives us a window on how water is stored underground and how that water interacts with vegetation, topography, and surface water in sloughs, springs and the Creek channel. Underground water (“groundwater”) is stored in tiny holes between grains of sand or gravel or in narrow openings in fractured clay or bedrock. In the karst country of southeast Minnesota there are caves and caverns that have actual underground streams of open water. But, in southwestern Minnesota, groundwater is stored in tiny pores or narrow fractures (“pore spaces”) found in layers of different geologic material (“aquifers”).

There are at least four aquifers along Kanaranzi Creek. Bedrock aquifers are deeply buried hundreds of feet below the land surface and information about them is limited. However, there are three distinctive water-bearing layers located at or very near the surface as shown in this sketch. The oldest is fractured gray clay with incorporated boulders that was deposited directly by glacial ice (“till”); it forms the hills and uplands along the Creek. The till is capped by wind-blown silt (“loess”) that also covers the intermediate age aquifer. That second aquifer is a sand and gravel layer deposited by glacial meltwater “(“outwash”); it underlies a flat terrace that stands just above the Creek. The third and youngest aquifer is a discontinuous layer of sand and gravel outwash that’s buried under stream sediments beneath the Creek’s floodplain.

We’ll look at the middle aquifer first because it’s characterized by distinctive vegetation patterns. Groundwater seeping out along the edge of the flat terrace is marked by patches of dark green plants. These are basically springs that might be used for livestock if they’re modified somewhat. My mother’s father used to talk about building a house near there because of the good water source. Although, it might not be too reliable as a domestic water source, it does contribute to wet conditions in row crop fields.   

About thirty years ago, drainage tile was installed in the cropland and the water flows down into a wetland on the floodplain below the terrace. It’s sort of hard to see the tile water through all the brown grass in the left photo. But, the right photo shows the dark green plants that grow around the springs at the terrace edge are distinctively different than the vegetation in the paddocks on top of the flat terrace surface or than the crops on the adjacent field. The water from the drainage tile helps to sustain the wetland at the base of the hill.

Where the main channel of the Creek gets close to the terrace, it erodes into the steep bank to give us a view of the geologic layers. The aquifer is sandwiched between the overlying wind-blown loess and the underlying glacial till. Black soil is developed at the top of the buff-colored loess and the light colored sand and gravel outwash lies on top of the glacial till.

In places, chemical reactions in the groundwater produce a cement that sticks the sand grains together to make a sandstone, but in most places the sand and gravel is loose and uncemented. Elongate cigar-shaped cemented areas may be an indication of groundwater flow directions. The boulders near the water are lag deposits from the till after the clay has been carried away by the flow of water in the channel. Those big rocks were probably not carried by the Creek, but rather are all that remains of the glacial till after all of the clay has been removed.

These last comments are speculative interpretations, but most of this post describes data that anyone can see. The older glacial till and the younger outwash buried beneath the floodplain are not as easily observed as this intermediate-aged terrace outwash. The cartoon at the beginning of this post is a “guess” about what’s underground. If we had data from test holes drilled every few hundred feet across the landscape, it would be a much more reliable interpretation. The next two aquifers are much harder to “see” and interpret, but the next several posts will look at them in more detail.

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Exposing Artifacts

Six generations of kids have hunted for arrowheads and buffalo bones along Kanaranzi Creek. But, in the last two or three years it seems like the high water levels have opened up a treasury of cultural resources. An archaeological survey of Rock County and two adjacent counties done in the early 1980s demonstrated that most sites are located along streams. There are currently 94 formally documented sites in Rock County listed by number in the Office of the State Archaeologist. Of those, 11 are classified as “artifact scatters” that have both lithic and/or ceramic artifacts; these may be habitation sites. Two of those sites with artifact scatters are located on Lone Tree Farm.

This summer, prehistoric corn cobs were found at the western site (21RK0019) and a piece of pottery was found at the eastern site (21RK0082). These are small and light-weight items that have probably been carried by the Creek from eroding steep channel banks and deposited on nearby sand bars called point bars. This map shows areas of erosion (areas in red) and deposition (areas in yellow) between 2016 and 2018. It’s speculated that erosion of the upstream steep, eroded banks has exposed archaeological features such as cache pits. The artifacts that are washed away are subsequently deposited at specific locations on the downstream adjacent point bars.

The light-weight piece of pottery and corn cobs were found near slow-moving, low water at the position where mud and sand have been deposited. The fragments of bone associated with the pottery and cobs are really small and don’t weigh much. Higher on the sand bar where fast-moving high water has deposited sand and coarse gravel, the pieces of bone are much larger and heavier. The photo on the left is of larger fragments from higher on the bar at the west site (21RK0019) where the corn cobs were found down close to the low water level. The photo on the right shows small bone fragments found with the piece of pottery on the lower part of the sand bar at the east site (21RK0082).

When the water is high, the current is strong and large pieces of bone or even big complete bones are dropped on the upper part of the sloping point bar. When the water level is low, the current is weaker so only small pieces are carried and deposited at a lower position on the sand bar. The left photo shows the locations big bones and little bones on the sand bar at the west archaeological site and the right photo shows the sand bar at the east site.

Record rainfall in 2018 and 2019 produced sustained high water flow conditions that ripped up a lot of the pasture. These fast-moving currents dropped some really big bones on the upper parts of the sand bars. Many medium-sized bone pieces were deposited at intermediate positions on the bars. These may have been shattered and cut during butchering; several buffalo skulls have been found at both sites. Some of the pieces almost look like tools, such as awls. However, it’s hard to really interpret their significance because they have been moved out of their original location in a buried archaeological feature. Context is super important and only systematic, professional excavation will lead to a realistic understanding of what happened here a thousand years ago.

There are, however, important implications for the archaeological sites along the Rock River and its tributaries in Rock County. Artifacts and bones may be deposited on sand bars just downstream from eroding steep channel banks that are cutting into buried archaeological features. This could be a serious threat to cultural resources that warrant “salvage” archaeological excavations.

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Conservation Crowdsourced

Back in the 1940s the US Department of Agriculture’s Natural Resources Conservation Services (NRCS) was called the Soil Conservation Service (SCS) and as a young beginning farmer my dad was using that as an information source. For example, we’ve got a file folder with a five-year crop rotation plan that’s a stark contrast to the two-year corn and beans rotation that is the current convention. He also grew and harvested brome seed as a part of the SCS involvement. There’s a family story of Dad turning brome seed by hand as it dried on the cement floor of the Sheep Shed. But, ideas and information sources evolve through time.

The smooth brome did a good job of suppressing weeds in the Creek pasture and it provided excellent fodder for cattle. The pasture is still dominated by tall smooth brome with Kentucky bluegrass as the understory close to the ground. The left photo shows new growth in a paddock recovering from grazing and the right one shows mature, ripe brome in a paddock not grazed this year. The cattle prefer the tender new growth as they’re rotated from paddock to paddock. However, the stiff stalks of the ripe brome can jab them in the face and cause eye infections.

We do have paddocks seeded to warm season grasses, but we’d like to diversify some areas from dominant brome to include native cool season grasses and other native plants. This is the seed tag from a commercial mix that I tried to frost seed by hand earlier this year. It would provide diversity because it had dominantly wild rye in it’s four main grasses plus about forty other species, including half a dozen plants that are found on one of the native prairie remnants that we’ve identified in the pasture. Problem is, it’s hard to see that anything really grew in part because a lot of the species are not easy to identify….at least for me. Also, I just had to take what was available in the commercial mix that only had a few species overlapping with the native plants we knew grew in the pasture.

And, THAT’S where the crowdsourcing comes in! I posted a question in a Face Book Group asking for suggestions on cool season grasses to replace brome and I hit a bonanza of information! Nine different people responded with the names of eight specific plant species and half of them were on our list from the native prairie remnant. That’s an important consideration because it demonstrates that those are species included in the existing indigenous seed bank in the pasture. It’s like a test of whether to include a specific species. What’s more, three of the respondents suggested wild rye grass that was also the dominant component of the commercial seed mix. Although rye is not currently on the list of plants in the prairie remnant, it already does play a significant role in one of our renter’s operation.

Growing, harvesting, and marketing rye for cover crop seed is one of the new enterprises that our renter has started. The photo on the left is a seeder specifically designed to plant rye for a cover crop. As a good cover crop, rye keeps roots in the ground to reduce erosion and increase soil health. In addition, combined with radishes and turnips, rye is a second crop that can be planted after beans have been combined or corn has been chopped; that mix is good for cattle grazing. But, wait! There’s more! If it’s not grazed, the more mature rye can be chopped for silage and fed away from the field. The photo on the right shows silage piled, waiting to be hauled away. AND, it turns out that rye can be the main component of a mix of cool season grasses used to increase diversity in the brome-dominated pasture.

Here’s some final information about the Face Book Group that provided the crowdsourcing. Although it’s called the “Minnesota Prairie Landowner Network”, the information generally has application in the tall grass prairie in adjacent states. I think that it just got started this year, so it’s a relatively new outfit and maybe that’s why I got such timely and useful input. There are about 275 members from diverse backgrounds including landowners, agency experts, nonprofit staff, and people who seem mainly just interested in prairie environments. The posts tend to be a lot of wild flower pictures and discussions about prairie restoration. But, if the responses to my initial inquiry are any indication, there’s plenty of information shared that relates to regenerative agriculture in a working landscape and that can be a help for folks who are actually farming the land.

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Place-Based Stacked Experiences

That’s a weird title! It’s trying to communicate that some places seem to host multiple experiences that don’t seem to be related. But, sometimes these “coincidences” have a common thread, other than sharing a specific location.

This picture taken in the early 1920s shows my dad and his older sister fishing with a view of the farm buildings to the south at the top of the wooded hill. The tall tree may be the large cottonwood that’s still there or it may be the actual Lone Tree itself because it didn’t fall down until 1930. This is about where the homesteaders’ children and grandchildren played along the Creek in the prior fifty years. It’s also very near the place where our children and grandchildren have fished, launched rafts, waded, and collected artifacts and bones and memories of adventures. That all happened from the 1970s up to the present time. But this is also the location of an exciting adventure that Dad had back in the early 1940s.

He was riding a horse parallel to the channel but back away from the edge of the steep bank when a beaver den collapsed under them and they fell into the hole! Fortunately neither the horse nor the rider was hurt, but it was a traumatic experience. The photo on the left shows the opening of a probable beaver den that I found just last week. It’s in almost exactly the same place as the accident, so Margaret and I did a “survey” (mostly just wading in the Creek, taking photos, and whacking at the exposed bank with a geology pick). The tunnel extends about six feet back into the bank and is about six feet from the top of the bank.

The high channel bank has a complex set of layers. The upper part is light-colored sand and dark-colored silt and clay deposited by the Creek. Below that is a layer of dark, soft clay above older glacial gravel exposed just to the north (left) of the photo. But, the opening to the beaver den is located right at water level in extremely hard gray clay that’s probably glacial till. It would be really tough digging for the beaver. The photo on the right is a view downstream from the den in the high bank toward the sandbar where an important artifact was found this past week.

The low water exposed sediments that most likely eroded from the high bank with the beaver den. This piece of pottery may have been carried by the current to the sandbar from the eroding bank. What if the beaver had help digging in the hard glacial till? What if he was actually just cleaning out a prehistoric cache pit exposed in the steep Creek bank? And, maybe that’s also what had happened back in the 1940s. Maybe Dad and his horse fell into a collapsed cache pit weakened by a burrowing beaver.

The piece of pottery is significant because it can be used to tell time. I sent a picture of it to a friend who is an archaeologist with expertise and he identified it as from the time of the Great Oasis people, about 1000 years ago. He also thought that it’s from a different vessel than the first piece of pottery that we found in this area. You can see some of the artifacts and bones at this post , see a picture of the first piece of pottery at the this post and see illustrations of cache pits here.

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Battling Brome

Prairie restoration programs often involve attempts to eradicate or at least limit smooth brome. This invasive, non-native, cool season grass is a vigorous sod-maker that usually expands to turn a pasture into essentially a monoculture. I understand why the restoration folks want to get rid of it, but it is also excellent for grazing. So in an attempt to diversify our brome and blue grass forage base, we’d like to find a way to locally control and replace brome.

We’ve got about a dozen patches of native prairie marked by big bluestem as the main indicator plant. The August 5 post linked here describes four of them. Among the dozen prairie patches, two are warm-season plantings, but the others are from preserved indigenous seed banks. Most locations are in areas where the stand of brome is thin, like obvious west-facing hill slopes. But, other locations seem to be associated with subtle small-scale topographic features. In this post we’ll relate a cluster of three prairie patches (circled in blue) to slight topographic highs and propose an experiment on a planted prairie patch (circled in red).

This past week a lot of the corn in our neighborhood was chopped for silage. This photo shows a “wall” of corn that illustrates the influence of subtle micro landforms in a floodplain setting. Green stalks mark wetter topographic low spots and brown ripe stalks spread over the subtle adjacent high spots. It’s a pattern that’s also seen in the brome and blue grass pasture.

This map has two-foot topographic contours that give a suggestion of subtle highs and lows that can be clearly seen when you’re actually walking the ground. More detailed elevation data would be helpful, but this information available from the county is adequate. There are limited stands of big bluestem mixed in with the brome on the subtle topographic high spots. However, the intervening low areas shown by brown blotches have no bluestem in the more dense brome development. This is essentially a top view of the pattern shown in a side view in the field of chopped corn.

The planted patch of big bluestem near our house has been established for about seven or eight years. However, in the last three or four years Margaret has maintained a mowed path around it. There’s been an on-going debate about this mowing. I hate to do any more mowing of tall grass (brome or bluestem) than is necessary, but she likes the trimmed look better. This year we noticed that the bluestem seemed to have expanded out toward the east and north mowed paths. Did the mowed brome at the margins of the patch allow the bluestem to expand through the root system or maybe the dominant wind from the south has dispersed bluestem seed to the north?

These two photos show the ground view of the two mowed paths. On the left, the bluestem with its distinctive red stalks, has reached the edges of the mowing on the east. On the right, the bluestem is also at the edge of a mowed area on the north. But, this is a newly mowed strip (marked by the brown grass) next to the long-maintained path (showing as the green area with brown grass clippings to the right). So, this is an experiment. Will the bluestem expand out into the mowed brome? Also, will Margaret be the ultimate winner of this long-standing debate about mowing the tall grass?

There are numerous anecdotes about native prairie plants expanding out of road ditches and fence lines. Maybe this unmanaged process can be replicated to coax expansion of established prairie patches on local subtle high spots out into the surrounding areas dominated by thick brome. Managed disturbances like grazing or burning (or mowing or spot spraying or even flooding) on the margins of the micro landforms may encourage the bluestem to grow out into the stressed brome. This might be an example of “precision conservation” because the topographic features that host the native plants are so small and subtle. In any case, this localized approach may provide an alternative to the wholesale conversion of brome-dominated paddocks.

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Prehistoric Corn Cobs

As Kanaranzi Creek erodes away the steep banks on the outer edges of meander loops, archaeological “treasures” continue to emerge and be deposited on adjacent sand bars. We think that’s what happened at the site described in the post of June 17 at this link. And, we think that it has also happened near the oxbow that hosts the pond and wetland described in many of the other recent posts. The newly-discovered “treasures” at the oxbow are corn cobs!

The Native Americans, who farmed river bottoms in this tall grass country 500 to 1000 years ago, raised corn along with squash and beans (a.k.a. the “three sisters”). They stored the corn in pits buried in the ground. These images are from displays at the Visitor’s Center at Good Earth State Park near Sioux Falls. The top of one of these cache pits in the floor of a dwelling is shown on the left and on the right we can see how the ears of corn were arranged in a side view. After the cache pit was emptied, it was often filled with trash and refuse.

Last fall, after several seasons of high water and erosion, I found this projectile point on a sand bar near the oxbow. Over the past 20 years, numerous buffalo bones have eroded out of the steep creek banks around the oxbow, including the skulls on the left and at the top of the second photo. In addition, there’s a circular vegetation anomaly in the area. About one-quarter mile upstream, the circular plant patterns at that site had expression in geophysical mapping recently described in a paper in the Minnesota Archaeologist by Megan Messerole. She interprets the mapping as expressions of cache pits and a possible dwelling and there are also artifacts and buffalo bones at this studied site. Now it looks like there may be a new, similar site near the oxbow where the contents of another cache pit may be eroding out of the Creek bank.

After the water levels dropped earlier this month, I fund more than two dozen corn cobs on one sand bar. They looked small and skinny and old….prehistoric? Online archaeology sources indicate that the prehistoric corn raised by Native Americans had 6 to 10 rows of kernels on each cob, while modern varieties generally have 16 to 20 rows. So, all that I had to do was count the rows. However, there is also another pattern that suggests erosion of a cache pit.

If the cobs came from a nearby, eroded bank, this was probably the only sand bar that had them. So, I went back down into the pasture and checked out four sand bars upstream and four downstream. This map shows that the upstream bars had no corn cobs and that three of the four downstream bars each had one cob. That’s exactly the way old-time prospectors would pan for gold. They’d follow the “color” upstream until they found the “mother lode” that was shedding the gold onto stream sediments. The eroding cache pit was probably in the steep bank circled on the air photo just upstream from the cob-rich bar, although there’s no sign of it currently shown in the bank.

But, are these really prehistoric corn cobs? They do look smaller than today’s familiar sweet corn. And, counting the rows of kernels on 17 of the best-preserved cobs supports the idea of ancient corn cobs. The counts ranged from 6 to 9 rows on each cob and had an average of 8. That’s well below the range of modern corn cobs. And, that’s also why the cobs on the right have pins stuck in them. The pins mark the row counts that provide the data. However, these prehistoric corn cobs are probably “treasures” only for old retired guys who are interested in archaeology!

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