Settlers in Bon Homme County created stone structures that were unique in the Dakotas. Several factors led to the emergence of chalkstone and fieldstone architecture in the area. Chalkstone was available, if quarried, from bluffs around the Missouri River, and a seemingly infinite supply of fieldstone could be gathered from the above and beneath the soil the settlers worked. Without much of a wood supply on the plains, stone made an excellent substitute material, if one knew how to work with it. Czech settlers, and to some extent Russo-German settlers as well, had often worked with stone in their home countries, and it was these settlers that built stone structures in Bon Homme County.
The explorers of the Lewis and Clark Expedition noted the attractive orange and pink-hued bluffs of Niobrara chalkstone above the Missouri River when they camped on Bon Homme island, near present Springfield, in September of 1804.
Tim Cowman is the State Geologist and Director of the South Dakota Geological Survey. "To understand what the Niobrara Formation is and how it was formed, we have to go back in geologic time to the Cretaceous Period, which ended about 66 million years ago," Cowman says. "During this time, a large sea covered most of the Great Plains, and at the bottom of the seabed, rock layers were being deposited and formed. At a time when the sea was very deep, all these little, microscopic animals that lived in the sea, like plankton and so on, that had calcareous shells died and settled to the bottom of the sea."
"Their calcareous shells then became cemented together and formed a layer of chalkstone and limestone, and that's what the Niobrara Formation is. Even though it was a lot of these small animals, microscopic animals, we often find in the Niobrara Formation some larger fossils. So, for example, you can also often find fossils of clam shells in the Niobrara Formation. And occasionally we find a plesiosaur or a mosasaur, which were large marine reptiles that were swimming in this sea and died and became incorporated into the formation as well."
There are surficial exposures of Niobrara chalk at various locations around the Great Plains.
"The Niobrara Formation exists under the majority of South Dakota," Cowman explains, "but in most cases it's buried at depth by other sediments. However, there are, what we call, outcrops or the surface variation of the Niobrara Formation along the Missouri River Valley, especially between Pickstown and Vermillion. Probably one of the best places to see them, is along the south shore of Lewis and Clark Lake. The majestic yellowish-brown bluffs that you see there are made up of the Niobrara Formation."
European immigrants would cut stone from these same bluffs to build their homes, churches and barns. Niobrara chalk was also used for making cement for a time at the old Western Portland Cement Plant in Yankton.
The Bon Homme Colony, the oldest and largest Hutterite colony in the region, once had several large structures built with chalkstone, including a waterwheel powered flour mill, a community center and a barn. Today, a small welding shop and a residence remain.
Most of Bon Homme County's historic chalkstone structures are in state of disrepair.
Probably the most well-maintained extant chalkstone structure in the area is the St. John the Baptist Church of Lakeport (Yankton County), built in 1884.
While chalkstone had to be harvested from specific locations, fieldstone was readily available everywhere.
"If we fast forward in geologic time up to about two million years ago, the Pleistocene Epoch started and that lasted until about ten thousand years ago -- basically the last ice age. During that time, large glaciers originating in Canada moved southward and covered approximately the northern third of the United States. But as these large ice sheets moved southward, they scraped up the rock that they were moving over. And so, there was a lot of igneous and metamorphic rocks, such as granites and quartzite in Canada and Northern Minnesota -- they got scraped up and incorporated into these glaciers. And then as the glaciers melted and retreated, they left these rocks behind in the native geologic formations of South Dakota."
The last Ice Age also deposited "glacial erratics" in Northern and Central Europe. Certain cultural groups, among them Czechs, brought with them to Eastern South Dakota an established history of building with fieldstone.
The John Frdyrych farmstead barn near Tyndall is probably the largest fieldstone building in the area, built with stone masonry and timber framing. But the barn is showing its age and could become a ruin without some reconstructive efforts.
"What my dad told me from his dad," says Mike Slama, who leases the land where the Frydrych barn stands, "is the Frydrych brothers, in the 1880's I think it was -- about the same time the railroad came through over here -- they started construction on this barn. They brought in all the rocks around here. It took them over seven years to build. I think it's over two hundred feet long and 30, 40 feet wide. And every rock that was put in this building was one at a time."
"When you stop and think of it," says Slama, "to start a barn this size was a major undertaking."
"My grandpa and them used to kind of work together back then," Slama recalls. "All the Czechs, the Bohemians, settled around west of Tabor over here. And if you've ever been in the Czech Republic everything id made with rocks there. So, this barn would kind of fit right in with the Czech culture."
Susan Paul's family has owned a homestead near Tyndall since 1900. A small fieldstone house on the property sat in a dilapidated state for many years, until Paul hired a crew of seasoned stone masons to reconstruct the home stone by stone.
"I would say, judging from the buildings that I have seen in Southern France, that have been restored, this restoration job would have to rank from good to very good," says Paul.
Sometimes stone masonry structures are hidden beneath a layer of stucco. Occasionally, where additions have been added, stone masonry walls exist only on the interior, and then can be concealed by layers of plaster or other materials.
The Sedlacek family spent a considerable amount of time uncovering an (over three foot thick) combination chalkstone and fieldstone interior wall in their home outside of Tabor.
"A lot of the times you'll see in these older constructions that to get the money lent to you to continue building or maintain a house like this isn't easy," says Erin Sedlacek. "Banks don't want to give you money to maintain a structure that they don't understand or insure a structure that they aren't sure is sound. But it's been standing here for one hundred seventy years. I would say it's sound, it's not going anywhere."