When white settlers arrived in north-central Kansas, during the 1870s-1880s, they found a dearth of wood for the construction of fences. After all, natural woodlands of the Great Plains are restricted to stream channels, some of which run dry for much of the year. Lucky for the settlers, a shallow sea had covered this area during the Cretaceous Period (135-65 million years ago) and a layer of limestone, deposited in that sea, lies just beneath the thin soil of this region, outcropping in many areas.
This rock, now known as the Fencepost Limestone, is the upper layer of the Greenhorn Formation, a layer cake of shales, mudstones and limestones, deposited in the vast, late-Mesozoic Sea. Rather soft, the Fencepost Limestone hardens with weathering and, since it is devoid of longitudinal faults and is only a foot thick, this rock layer proved to be ideal for making posts to support barbed wire fencing. Of course, this readily accessible limestone was also used for the construction of homes, barns, town halls and other structures.
Today, those who travel along Interstate 70 can easily observe these limestone fence posts and buildings, especially in the vicinity of Russell, Kansas. They certainly have held up well over the past 140 years!
