Fencepost limestone
Fencepost limestone, Post Rock limestone, or Stone Post is a stone bed in the Great Plains, known for its historic use as fencing and construction material in north-central Kansas resulting in a unique cultural expression. The source of this stone is the topmost layer of the Greenhorn Limestone formation. It is a regional marker bed as well as a valued construction material of the late 19th and early 20th centuries in Kansas. This stone was very suitable for early construction in treeless settlements and it adds a notable rust orange tint to the region's many historic stone buildings. But the most famous use is seen in the countless miles of stone posts lining country roads and highways. This status gives rise to such regional appellations as Stone Post Country, Post Rock Scenic Byway, and The Post Rock Capital of Kansas. This rustic quality finds Fencepost limestone still used in Kansas landscaping today.
Background
The Fencepost limestone is a relatively thin, resistant, and recognizable bed of stone that forms the middle range of bluffs in the Smoky Hills region of north-central Kansas, ranging from the Nebraska border near Mahaska, Kansas, about 200 miles southwest to within a few miles of Dodge City, Kansas, where it is seen in the buildings of the farms and cities of the area.The Fencepost limestone is unique for its contribution to the cultural landscape of Kansas, appearing as miles of stone fence posts lining austere fields and pastures. The drier climate coupled with the grazing habits of buffalo and the prairie burning practices of Plains Indians meant that the first European settlers to the region did not have enough local timber for construction and fencing. However, a suitable, easy to quarry stone was available. No other "area of the world has used a single rock formation so extensively for fencing."
The source of this tough chalky limestone is the widespread and persistent topmost bed of the Greenhorn Limestone. The Fencepost limestone is the exceptionally wide ranging marker of the conformal contact between the Pfeifer Shale, which is the uppermost member Greenhorn Limestone below, and the Fairport Chalk, the lowest member of the Carlile Shale formation above.
This stone was first scientifically mentioned as the "Fencepost limestone" by F. W. Cragin in 1896 when he originally attempted to name it Downs limestone. The Fencepost bed has also been called Benton limestone for its prominence as a marker for the now generally obsolete Benton Group classification.
Reporting on the "Fence-Post Horizon" in 1897, W. N. Logan noted fifty thousand stone posts in Mitchell and Lincoln counties alone. Since then, the informal name "Fencepost limestone bed" has come to have a stature equal that of the adjacent members. The greatest use of the Fencepost limestone, for fencing and building, was from 1884 to 1920.
Effective July 1, 2018, Kansas Legislation HB 2650 designated Greenhorn Limestone formation, specifically "the famous "post rock" limestone" bed of that unit, to be the state rock of Kansas.
Uses
Fencing
On the early open ranges of the Kansas frontier, typically, the burden was on the farmers to protect their crops from free-range and driven cattle.Common practice of earlier frontier farmers in the East and the in Old Northwest Territory was to use the timber cleared from the new fields for split-rail fencing. But, at the time of American settlement, Kansas was largely treeless. Owing to the intensive grazing of millions of buffalo, as well as to the particular land management of the 19th century Plains Indians, the small amount of timber that was available was confined to river banks.
In eastern Kansas, abundant, large, flinty stones could be collected from the hills and fields to build long stone walls. However, in several counties in central Kansas, where most of the rock was soft shale or chalk, a practical alternative was available; one particular bed of stone had ideal properties to substitute for wood fenceposts. Forming the posts required some labor and the posts are heavy – – but, with the recent invention of barbed wire, only one post was needed every or so.
The relative ease of forming durable stone posts from Fencepost limestone is not to be neglected in the context of a treeless frontier farming economy. The bed is not deeply buried, requiring relatively little effort to uncover. Fresh exposed slabs are soft and easy to work; the stone hardens only after removal from the shale and drying out in the open air. Curiously, the natural bed is not jointed; so several long rows of complete posts or large slabs can be split off of a large exposed sheet of limestone without breaking. No heavy equipment is required, and community blacksmiths could easily make serviceable tool sets.
Lines of the oldest stone posts have stood in place for well over a hundred years. But in the 1920s, rural labor costs had increased to the point that stone posts could no longer be made and installed as cheaply as mass-produced steel and treated wood post. As stone post fences are removed or are replaced with steel or wood post fences, the stone posts are usually collected for reuse, often in landscaping, but, because of their greater weight and strength, they are also used as corner posts in new fences.
Currently, the Permian top-ledge Cottonwood Limestone is commercially split and shaped to superficially resemble the Kansas Stone Posts. Examples are seen in the Kansas Veterans' Cemetery at Wakeeny. These "faux" post rocks can be detected by their all-white color, presence of fusulinids, larger drill size, absence of iron staining, and absence of Cretaceous mollusks.
Quarrying
Kansas' stone fenceposts were manufactured from bluffs that had been cut by regional rivers through the Blue Hills. On these hills, the unweathered limestone bed can be exposed by removing shallow overburden. Quarrying leaves a long trench from in width in which water can collect after a rain.Traditionally, these posts were manufactured in-place by drilling lines of holes directly into the freshly exposed, soft limestone bed. Then feathers and wedges were set into the holes and the wedges hammered to split the posts off. The posts were generally used with the rough quarry face finish; so the drilled holes usually remain visible. After farmers began making these Stone Posts, building blocks for construction were quarried from the bed in the same way, so the drill holes the quarry faces are often visible in buildings unless removed by hammered or pitched face finishing.
Traditional hole splitting can still be used in Fencepost limestone quarries remaining today, especially if the rustic finish is desired; however, saw cutting of the limestone in-place is also done, depending on the product finish desired.
Construction stone
A regional construction material, Fencepost limestone appears yellowish to buff with orange to brown tinted streaking, sometimes weathering to nearly white in color when openly exposed for many decades. Use of this particular limestone bed of for construction slightly preceded the realization that it could be used for fenceposts. First homes for settler farmers on the treeless prairie were typically dugouts and sod houses. Commercial dimensional lumber was an expense ill-afforded by settler farmers, even more so where it had to be shipped in from out-of-state. The Greenhorn Formation has many limestone beds, but most are too thin, too soft, or too fragile to be used in permanent buildings. The Fencepost bed, however, has convenient thickness and is easily worked into tough, durable, and decorative building blocks. Its resistance to erosion compared to the overlying Carlile Shale results in it forming broad bluffs or plateaus; so, it is abundant and relatively easy to quarry. In an age of kerosene lamps and coal stoves, it was a fireproof alternative to scarce timber.File:PfeiferAssemblage 01.jpg|thumb|right|Shiner-laid Fencepost limestone displaying Baculites yokoyamai and other fossils on the exterior of the First United Methodist Church of Hays.
It was normal to lay the Fencepost limestone with its bedding plane horizontal; so, fossils can only be seen in thin cross section in the walls of almost all buildings built with Fencepost limestone. However, when laid in this stretcher fashion, the characteristic red-orange or brown lines are displayed. Many buildings have the limestone left with quarry face, many showing the holes drilled for splitting. Some buildings may have hammered finish, others pitched. The Ellis County courthouse is a large example of sawed, stretcher course Fencepost limestone. It is uncommon to see this stone set in walls in vertical "shiner" orientation, but such an orientation can show off the fossil content. An example of this is the First United Methodist Church of Hays built in 1949; here the Fencepost limestone was cut into slabs and set vertically; and its index fossil, Collignoniceras woollgari, is displayed in well-preserved cross sections in a few places.
Use of Post Rock in buildings declined in the 1920s as concrete came into greater use. Resurgence occurred in the use of the stone in public buildings in the 1930s as these were built as WPA projects. Use of the Fencepost limestone continued to later times through very few examples, more likely to use sawn and shiner-laid stone than the historic buildings. Later examples include the Guaranty State Bank, Beloit, 1958, and the Gross Field House and Coliseum, FHSU, 1960s and 1975.