- Stone posts with "sheep fencing", Munjor
- Recreated stone post fence at the Santa Fe Trail Center
- Post rock fencing near Liebenthal.
Fencepost limestone | |
---|---|
Stratigraphic range: Turonian ~ | |
Type | Geological marker bed |
Unit of | Greenhorn Formation |
Underlies | Carlile Formation |
Overlies | Uppermost beds of the Greenhorn Formation |
Thickness | 9–14 inches (0.23–0.36 m) |
Lithology | |
Primary | Chalky limestone (coccolithic) |
Other | Microsparry calcite matrix Inoceramus shells and fragments Yellow, orange, or brown stainings and nodules of Limonite |
Location | |
Country | United States |
Extent | Outcrops from the Nebraska border near Mahaska, Kansas, about 200 miles southwest to a few miles from Dodge City, Kansas. [1] Recorded in well logs throughout the High Plains. [2] |
Type section | |
Named for | Use as stone fenceposts |
Named by | F. W. Cragin [3] [4] |
Year defined | 1896 |
Fencepost limestone, Post Rock limestone, or Stone Post is a stone bed in the Great Plains notable for its historic use as fencing and construction material in north-central Kansas resulting in 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, [5] Post Rock Scenic Byway , and The Post Rock Capital of Kansas . [6] This rustic quality finds Fencepost limestone still used in Kansas landscaping today.
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, [1] 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, [8] 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 [9] 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." [7]
The source of this tough chalky limestone is the widespread and persistent [10] 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. [3] 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. [4] Since then, the informal name "Fencepost limestone bed" has come to have a stature equal that of the adjacent members. [10] The greatest use of the Fencepost limestone, for fencing and building, was from 1884 to 1920. [11]
Effective July 1, 2018, Kansas Legislation HB 2650 [12] designated Greenhorn Limestone formation, specifically "the famous "post rock" limestone" bed of that unit, [13] to be the state rock of Kansas.
When Europeans settled in north-central Kansas, they found vast grasslands. With few trees available, they quarried a thin, shallow bed of Cretaceous limestone for buildings, bridges, and fenceposts. No area of the world has used a single rock formation so extensively for fencing. Today that rock layer is called Fencepost limestone and north-central Kansas is known as the Land of the Post Rock. [7]
— Commemorative plaque on the carved Fencepost limestone sign for the Kansas Geological Survey, Lawrence, Kansas
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. [14]
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. [9]
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 – 250–450 pounds (110–200 kg) – but, with the recent invention of barbed wire, only one post was needed every 30 feet (9.1 m) or so. [15]
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. [16] 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; [17] 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. [18]
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. [19] 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.[ citation needed ] These "faux" post rocks (such as seen on the left in the cited image[ citation needed ]) can be detected by their all-white color, presence of fusulinids, larger drill size, absence of iron staining, and absence of Cretaceous mollusks.
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 10 to 20 feet (3.0 to 6.1 m) in width in which water can collect after a rain. [20]
Traditionally, these posts were manufactured in-place by drilling lines of holes directly into the freshly exposed, soft limestone bed (only about halfway through). Then feathers and wedges were set into the holes and the wedges hammered to split the posts off. [21] 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, [22] especially if the rustic finish is desired; however, saw cutting of the limestone in-place is also done, depending on the product finish desired.
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. [15]
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. [15] The Ellis County courthouse is a large example of sawed, stretcher course Fencepost limestone. [26] It is uncommon to see this stone set in walls in vertical "shiner" orientation, but such an orientation can show off the fossil content. [15] An example of this is the First United Methodist Church of Hays built in 1949; here the Fencepost limestone [27] 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. [28]
Nostalgia for the stone post fencing, as well as the unique coloration and rustic quarry facing of the stone, finds the posts and the source limestone used in modern landscaping in locations as far away from the outcrop as people are willing to haul it. Commonly, original posts removed from demolished or replaced stone post fences are repurposed. [8] Also, blocks of Fencepost limestone are recovered from collapsed or demolished buildings. [29] Fresh stone is also quarried [30] for landscaping and novelty products. [31] [32]
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We've got the highest quality quarried limestone anywhere right here.
Roughly only a foot thick, fine-grained Fencepost limestone has seen limited use in public sculpture. However, the ability to make large stone slabs has seen the adaptation of the bed to bas-relief. The bas-relief technique permits the artist to manipulate the variations of tone within the slab. Past Victoria sculptor John Linenberger used this technique in a carving on the convent adjoining the St. Fidelis Church, carving through the brown layer to expose the lighter interior stone. [34] Hays sculptor Peter "Fritz" Felten, Jr., used the same technique in plaques mounted in the sloping pedestal of his Monarch of the Plains at the Fort Hays State Historic Site. [35]
More recent Pete Felten sculptures, Train Hwy (1995) and Pteranodon (2000), [36] demonstrate use of the tones of the Post Rock, which locally can have outer brown layers with a lighter inner core. In Pteranodon, displayed at Exit 161 on Interstate 70, the head is carved from brown Fencepost limestone, oriented so that the dinosaur's crest and bill are the exposed lighter-shade inner core of the limestone.
The multi-tone effect is also seen in Stone Post slab sculptures displayed at the Fossil Station Convenience Store at Russell, adjacent to exit 184 of I-70. [37] The weathered Post Rock used here is particularly white, but with a blackened top layer and red-toned inner core. One bas-relief carving is of a Buffalo, the shallow cut into the blackened layer meant to suggest the dark hide of the bison. The other carving is of the Hereford breed of cattle, a breed with red body and white face; the stone is carved so as to reveal the redness in contrast to white face and horns.
California sculptor Fred Whitman has carved several sculptures from antique Stone Posts. Near Lucas, Fred has carved faces of four Lucas residents into four Stone Posts standing in fences along the Post Rock Scenic Byway. [38] [39]
The Fencepost limestone has a particular usefulness in hydrocarbon exploration. While it is certainly too thin to be a viable hydrocarbon reserve, even for fracking, the Fencepost is located close to known producing layers, and has a particular quality that is useful in locating them. The Fencepost shows a unique "double-peak" or "prolonged kick" in electric well logs, and can be used to locate reserve formations in several states north and west of Kansas. Consequently, the Fencepost bed has been used as a datum (a fixed reference point) in charting subterranean sections of rock lying under the High Plains. [2] [40]
Like several of the thin limestones of the upper Greenhorn and lower Carlile, the Fencepost bed is a shell-rich, coccolithic, chalky limestone; however, this bed is hardened by a crystalline matrix of sparry concretory calcite so that it is more resistant to weathering and erosion. Unexposed, the Fencepost is olive-gray, weathering to light grey on exposures. When well exposed, it lightens to buff and yellow-orange with one or more orange, rust, or brown streaks. This coloration is due to limonite (rust), an oxide of iron, and is a trace effect of volcanic activity in the Sevier orogeny. [41] Across the range of the outcrop, the limonite weathers out in a variety of shades and patterns as seen the collage on the right. This coloration varies from barely visible to one, two, or more shaded zones. The exposed stone often weathers out a parting seam, also seen in the collage, used split the limestone into thinner slabs for flagging. [15] Limonite is often concentrated along the parting seam, sometimes to the point of forming small nodules or concretions. The top and bottom of the post's bedding can blacken with prolonged exposure to the weather above ground.
The regional reputation of the Fencepost limestone bed belies its physical size and relative rank in the rock layers associated with the lower Colorado Group.
The majority of the particular Western Interior Seaway sequence above and below the Fencepost bed, a group of layers originally called the Benton Group, is characterized by gray, dark gray, or blue-gray flaky shales. This is in contrast to the red and yellow massive sandstones and clays of the Dakota Formation below and the massive buff limestone and chalk beds of the Niobrara Formation above. Distinct from most of the overlying Carlile Shale formation, the members of the Graneros Shale and Greenhorn Limestone formations feature many thin, repeating "rhythmic" layers of limestone and shale. This feature is well displayed by the Jetmore Chalk and Pfeifer Shale members, but is seen in some form in all members and extends above the Fencepost bed into the Fairport Chalk member of the Carlile. [42]
So, the Fencepost limestone can be seen as just one thin chalky limestone bed out of dozens of superficially similar, thin chalky limestone beds. It is also not the only such bed in that strata to have an orange streak. It is not even the thickest limestone bed in those formations (the Jetmore Chalk Shellrock bed is the thickest [43] ). However, it is still thicker than most of the other local limestones and it is particularly most resistant to weathering and so it forms the tops of the central ridges and plateaus of the Smoky Hills. [44]
The Fencepost bed has also been called Benton limestone [4] for its prominence as a marker for the now generally obsolete Fort Benton Group classification. Before the 1930s, the chalky shales between the Dakota and the Niobrara formations were called the Fort Benton formation or Benton Limestone. [45] As noted, the greyish, chalky shale with great many thin limestones between those formations stood in sharp contrast to the massive orange/red sandstone below and the massive buff limestone and chalk above. It was this distinctiveness that led to the initial classification of this sequence as the Benton Group with the Fencepost limestone as the central marker. [45] There being only one limestone in the Benton generally suitable for construction use, and that one also being the only one containing abundant Collignoniceras woollgari fossils, when any literature describes a building as built out of "Benton limestone" (a more common usage years ago in Hays), it should be taken as being the Fencepost limestone. [46]
Based on the consistency of the structures and fossils above and below the Fencepost bed, the general depositional environment of the Fencepost is considered to be the same as both the Fairport Chalk above and the Pfeiffer Shale below. In fact it has been commented that bed does not really mark any real, overall change in species or environmental patterns. [47]
These layers are interpreted as representing the maximal extent and depth of the Greenhorn cycle of the Western Interior Seaway, with the Fencepost practically marking the central event. Depths are estimated to be only 100–500 feet (30–152 m), venturing into the Mesopelagic (twilight) depths, perhaps even to 1,000 feet (300 m) or more. [41] This was a place and time of open seas with little direct sedimentary or nutrient influence from land, although petrified sunken driftwood is not extremely rare within the Fencepost. There was generally limited oxygen at the seafloor, and bottom currents were weak, but sufficient for tidal feeders. The primary source material for the chalky deposits was remains of the productive algae and plankton of the warm sea that precipitated onto the sea floor (after having been digested and pelletized by tiny animals). The resulting carbonate mud supported hardly any foraminifera. Only bivalves that were adapted to "floating on the mud", or those sessile, tidal feeding creatures that could attach to such shells, could thrive on this bottom. Consequently, the floor itself was frequently covered with mollusks, especially species of Inoceramus , ranging in size from few millimeters to well over a meter, themselves encrusted with oysters. [41]
There were several species of free-swimming ammonites, Baculites, and belemnites, which serve as index fossils within the members of the Greenhorn and Carlile formations. Abundant fish populations of the Greenhorn sea supported the largest of predators; great fish, sharks, and reptiles alike, including plesiosaurs, mosasaurs, elasmosaurs, [48] and Xiphactinus . [49]
More than any other rock bed in of the lower Colorado Group, the Fencepost makes durable displays of marine fossils of the Cenomanian and Turonian ages; particularly in shiner-laid masonry, [15] fenceposts, landscaping pieces, and flagging. Visible fossils present in the Fencepost limestone bed are the same invertebrate fossils of the Pfeifer Shale member, which also continue into the lower Fairport Chalk member. [17] The presence of these particular index fossils species helps identify the Fencepost bed as distinct from the limestone beds of the Fairport Chalk above and the Jetmore Chalk member below. The most easily spotted fossil is the Inoceramus (Mytiloides) labiatus (Schlotheim), including a broad/flat form subpopulation that appears in the vicinity of the Fencepost. Other common Fencepost fossils include Inoceramus cuvieri Sowerby, Collignoniceras woollgari, Baculites yokoyamai Tokunaga and Shizimu, and Pseudoperna bentonensis ( Ostrea congesta var. bentonensis) [50]
The Fencepost bed is a strong marker bed rising almost to member status in significance. [10]
Generally the outcrop is easy to locate and identify: The outcrop of the Fencepost is consistently found forming a bench, bluff, or plateau; [51] fine examples are seen in the bluffs lining the valley at and downstream of Wilson Lake. There is a specific, reliable sequence of shale, limestone, and bentonite marker beds below the Fencepost. While the layers above the bed are equally consistent, they are usually set back from the outcrop by a good distance, often spread out over miles. As such, geologists were naturally encouraged to define the Fencepost as a convenient, upper limiting bed of a formation; the rock layers that formed the steep bluff beneath the Fencepost were named one formation (Greenhorn), while the rock layers that formed the low rolling hills above the Fencepost were named as another formation (Carlile).
So, the Fencepost has been mapped as the topmost bed of both the Pfeiffer Shale member (placing it at the top of the Greenhorn Limestone) as well as at the bottom limit of the Fairport Chalk member (and the Carlile Shale). However; either lithostratigraphically or biostratigraphically, there is little other reason to define members or formations with the Fencepost as a boundary; the lowest several feet of the Fairport Chalk is remarkably similar to the highest several feet of the Pfeifer Shale: [47]
However, along the steep bluffs lining the Smoky Hill and Saline rivers, the Pfeifer [52] and Jetmore are exposed close by the Fencepost, while all but the first 17 feet (5.2 m) of the Fairport is usually laid out some distance from the ledge, often miles.
The Fencepost limestone can be identified in the field and in buildings by the unusual character and content of the rock itself; but also by understanding of features of the general geology of the locations, especially the marker beds that prove the identity of the Fencepost bed. [53]
The "Fencepost" limestone forms a conspicuous ledge in the Blue Hills subregion of the Smoky Hills. [54] Both above and below the Fencepost are zones of unusual, flatten spheroid or ovoid limestone concretions. About 6 feet (1.8 meters) below the Fencepost is a small but pervasive marker bed that unambiguously identifies the Fencepost limestone above; the "Sugar Sand", a 1–2 inches (2.5–5.1 cm) bentonite seam filled with a "sand" of calcite crystals. [17]
Other nearby beds
In the field, other nearby limestone beds with similar visual features can be confused for the Fencepost limestone; [55] moreover, some of these limestone beds have also seen limited use in fencing or building. [20] However, these are also prominent marker beds and their features can help locate and identify the Fencepost by comparison.
There are great many sights of Stone Post Country, outcrops, fences, and buildings, that are available to auto touring. [64] [65] [66]
Interstate 70 passes right across the center of Post Rock Country. [67] [68] The stone posts are seen in the countryside some 20 miles (32 km) west of Salina as this highway enters the scenic Dakota Escarpment, now topped by the Smoky Hills Wind Project. Sights of stone fenceposts and stone buildings constructed of the Fencepost limestone are common from there westward some 70 miles to just past Hays. Side trips can be made into numerous Post Rock communities. From mile 223 to mile 195, among the wind turbines, the Interstate threads the level of the Fencepost outcrop. Between Exit 221 (Lucas) and Exit 219 (Ellsworth), Avenue B is a frontage road with exposures of Fencepost limestone. [69] The thin bentonite marker can be seen below the Stone Post bed here. Fragments of Inoceramus labiatus, Inoceramus cuvieri , Collignoniceras woollgari, and Baculites yokoyamai can be seen. Please do not collect from this exposed public location.
The Post Rock Scenic Byway passes between the Post Rock communities of Wilson and Lucas. From Wilson, the highway rises to the Fencepost outcrops, then drops down into the colorful Dakota Hills south of the lake. Crossing the dam, the views include the Fencepost bluffs of the Blue Hills lining the Saline Valley. [67]
Now featuring a folk art community, [70] Lucas is also long known as the location of Samuel P. Dinsmoor's Cabin Home and Garden of Eden statuary garden. Rather than the conventional stone block masonry courses, Dinsmoor envisioned constructing homes with "logs" cut from the Fencepost bed, carved to lock together in the fashion of the logs in a log cabin. [71]
U.S. Highway 183 interchanges with Interstate 70 at Hays. Several public buildings, churches, and university buildings in Hays are constructed of Fencepost limestone. [72] [73]
Highway 183 passes no Fencepost limestone north of Hays as there it enters the Fort Hays Limestone region. However, south of Hays, the highway passes the small Post Rock communities of Schoenchen, Liebenthal, and La Crosse. Near Schoenchen, the stone posts were cut from long quarries that followed the bluff along the north of the river. On the plain between the Smoky Hill River and Liebenthal, the Fencepost bed is shallow, and can be seen outcropping in draws along the highway. [74] [75]
U.S. 183 cuts south through an abandoned Fencepost quarry as it approaches the Smoky Hill River bridge near Schoenchen. [76] Just uphill from the quarry, limestone and shale of the Fairport Shale are exposed in the road cut. Facing west from the highway, the quarry is south of the red utility warning signs. The Fencepost makes a poor exposure next to the highway here, mostly having been quarried off of the bluff. At the depth where it would be found in the road cut, it mostly buried. A resistant marker bed of the Fairport Chalk (F-3) is seen a short distance up the hill, and from the erosion of the shale, this limestone seems to have drawn a lot of attention in the years since this section of U.S. 183 was widened in 1966. On private property, the quarry can be viewed from the fence line along the road cut. A limestone shelf is seen jutting from the old face of the quarry; but, this is not the Fencepost, which would be a bit below the level of the floor under the hillside. This visible limestone is the "limestone above the Fencepost" (Fairport Chalk marker F-2). This limestone is about half as thick as the Fencepost, and can tend to split at a limonite seam; otherwise, it is nearly as durable as the Fencepost and similar in color, and so was used as flagging. [77]
The Post Rock Museum is located on the south end of La Crosse. Examples of Post Rock populate the park that this museum shares with the Rush County Historical Museum (occupying the relocated Timken train station), the Nekoma Bank Museum, and the Kansas Barbed Wire Museum. The Post Rock Museum contains a recreated stone post quarry, assorted quarrying tools used in the area, and a fossil collection. [78]
Vonada Farms and Stone Company is located 6.5 miles (10.5 km) north of Sylvan Grove, Kansas. Tours can be arranged, see the Kansas Sampler Foundation pages. [32]
Bluestem Quarry and Stoneworks operates near Lucas, Kansas. [79]
Other communities with abundant Fencepost limestone architecture:
Fencepost limestone/Dakota sandstone boundary communities:
Clunch is a traditional building material of chalky limestone rock used mainly in eastern England and Normandy. Clunch distinguishes itself from archetypal forms of limestone by being softer in character when cut, such as resembling chalk in lower density, or with minor clay-like components.
Sugar sand may refer to:
The Smoky Hills are an upland region of hills in the central Great Plains of North America. They are located in the Midwestern United States, encompassing north-central Kansas and a small portion of south-central Nebraska.
The geology of Kansas encompasses the geologic history and the presently exposed rock and soil. Rock that crops out in the US state of Kansas was formed during the Phanerozoic eon, which consists of three geologic eras: the Paleozoic, Mesozoic and Cenozoic. Paleozoic rocks at the surface in Kansas are primarily from the Mississippian, Pennsylvanian, and Permian periods.
The Niobrara Formation, also called the Niobrara Chalk, is a geologic formation in North America that was deposited between 87 and 82 million years ago during the Coniacian, Santonian, and Campanian stages of the Late Cretaceous. It is composed of two structural units, the Smoky Hill Chalk Member overlying the Fort Hays Limestone Member. The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway, an inland sea that divided the continent of North America during much of the Cretaceous. It underlies much of the Great Plains of the US and Canada. Evidence of vertebrate life is common throughout the formation and includes specimens of plesiosaurs, mosasaurs, pterosaurs, and several primitive aquatic birds. The type locality for the Niobrara Chalk is the Niobrara River in Knox County in northeastern Nebraska. The formation gives its name to the Niobrara cycle of the Western Interior Seaway.
Colorado is a geologic name applied to certain rocks of Cretaceous age in the North America, particularly in the western Great Plains. This name was originally applied to classify a group of specific marine formations of shale and chalk known for their importance in Eastern Colorado. The surface outcrop of this group produces distinctive landforms bordering the Great Plains and it is a significant feature of the subsurface of the Denver Basin and the Western Canadian Sedimentary Basin. These formations record important sequences of the Western Interior Seaway. As the geology of this seaway was studied, this name came to be used in states beyond Colorado but later was replaced in several of these states with more localized names.
The Carlile Shale is a Turonian age Upper/Late Cretaceous series shale geologic formation in the central-western United States, including in the Great Plains region of Colorado, Kansas, Nebraska, New Mexico, North Dakota, South Dakota, and Wyoming.
Fossiliferous limestone is a type of limestone that contains noticeable quantities of fossils or fossil traces. If a particular type of fossil dominates, a more specialized term can be used as in "Crinoidal", "Coralline", "Conchoidal" limestone. If seashells, shell fragments, and shell sand form a significant part of the rock, a term "shell limestone" is used.
Megacephalosaurus is an extinct genus of short-necked pliosaur that inhabited the Western Interior Seaway of North America about 94 to 93 million years ago during the Turonian stage of the Late Cretaceous, containing the single species M. eulerti. It is named after its large head, which is the largest of any plesiosaur in the continent and measures up to 1.75 meters (5.7 ft) in length. Megacephalosaurus was one of the largest marine reptiles of its time with an estimated length of 6–9 meters (20–30 ft). Its long snout and consistently sized teeth suggest that it preferred a diet of smaller-sized prey.
The Graneros Shale is a geologic formation in the United States identified in the Great Plains as well as New Mexico that dates to the Cenomanian Age of the Cretaceous Period. It is defined as the finely sandy argillaceous or clayey near-shore/marginal-marine shale that lies above the older, non-marine Dakota sand and mud, but below the younger, chalky open-marine shale of the Greenhorn. This definition was made in Colorado by G. K. Gilbert and has been adopted in other states that use Gilbert's division of the Benton's shales into Carlile, Greenhorn, and Graneros. These states include Kansas, Texas, Oklahoma, Nebraska, and New Mexico as well as corners of Minnesota and Iowa. North Dakota, South Dakota, Wyoming, and Montana have somewhat different usages — in particular, north and west of the Black Hills, the same rock and fossil layer is named Belle Fourche Shale.
The Greenhorn Limestone or Greenhorn Formation is a geologic formation in the Great Plains Region of the United States, dating to the Cenomanian and Turonian ages of the Late Cretaceous period. The formation gives its name to the Greenhorn cycle of the Western Interior Seaway.
The Americus Limestone is a member of the Foraker Limestone Formation in eastern Kansas, where it is quarried as a distinctive ornamental stone. In outcrop, it is typically recognized as two relatively thin but persistent beds of hard limestone separated by shale that forms the lowest prominent bench of the many benches of the Flint Hills. The recognizable facie of the member in excavated or eroded exposures is two thin limestone beds separated a bed of shale and adjacent shales above and below having a particular gray or bluish color darker than higher limestones. A third, lower, highly variable algal limestone is often present and included as the base of the member. The unit is not particularly massive, the limestone pair totaling 3 to 4 feet in places, more in other locations but less to the North, and up to nearly to 9 feet at the type location of Americus, Kansas. The addition of the lower algal limestone as a base for the unit increases the thickness to over 18 feet. Initially thought to be the lowest of the Permian rock of Kansas and as such classified as the lowest unit of the Council Grove Group, the unit is now dated within the uppermost Late Carboniferous.
The Wellington Formation is an Early Permian geologic formation in Kansas and Oklahoma. The formation's Hutchinson Salt Member is more recognized by the community than the formation itself, and the salt is still mined in central Kansas. The Wellington provides a rich record of Permian insects and its beddings provide evidence for reconstruction of tropical paleoclimates of the Icehouse Permian with the ability in cases to measure the passage of seasons. Tens of thousands of insect fossil recovered from the Wellington shales are kept in major collections at the Harvard Museum of Comparative Zoology and Yale Peabody Museum of Natural History.
The Benton Shale is a geologic formation name historically used in Montana, Wyoming, North Dakota, South Dakota, Colorado, Kansas, and Nebraska. In the "mile high" plains in the center of the continent, the named layers preserve marine fossils from the Late Cretaceous Period. The term Benton Limestone has also been used to refer to the chalky portions of the strata, especially the beds of the strata presently classified as Greenhorn Limestone, particularly the Fencepost limestone.
The Favel Formation is a stratigraphic unit of Late Cretaceous age. It is present in southern Manitoba and southeastern Saskatchewan, and consists primarily of calcareous shale. It was named for the Favel River near Minitonas, Manitoba, by R.T.D. Wickenden in 1945.
Cottonwood Limestone, or simply the Cottonwood, is a stratigraphic unit and a historic stone resource in east-central Kansas, northeast-central Oklahoma, and southeastern Nebraska in the Midwestern United States. It is the lowest member of the Beattie Limestone formation and commonly outcrops within the deep valleys and on top of the scenic residual ridges of the Flint Hills.
The Fort Riley Limestone is a Kansas Permian stratigraphic unit of member rank and historic building stone, sold commercially as fine-grained Silverdale, having at one time been quarried at Silverdale, Kansas. This limestone outcrops in east-central Kansas, extending into northeast-central Oklahoma and southeastern Nebraska, in the Midwestern United States. Its conspicuous "rim rock" marker horizon outcrop caps the bluffs overlooking the original buildings of Fort Riley, as well as the Marshall Army Airfield opposite the Kansas River.
The Fort Hays Limestone is a member of the Niobrara Formation of the Colorado Group exposed in Colorado, Kansas, Nebraska, and South Dakota and is named for the bluffs near the old Fort Hays, a well-known landmark in western Kansas.
Inoceramus cuvieri is an extinct species of the extinct genus Inoceramus of Bivalve mollusks that serves as an index fossil of chalky rocks of Turonian age of the Cretaceous Period in Europe and North America.
Juana Lopez refers to both the uppermost member of the Carlile Shale formation and to the environment that caused it to form. The Juana Lopez Member is calcareous sandstone dated to the Turonian age of the Upper Cretaceous and is exposed in the southern and western Colorado, northern and central New Mexico, and northeastern Utah. The unit has been described as "the most enigmatic" member of the Carlile Shale.
Datum: top of Greenhorn Limestone
Downs limestone. Limestone 6 to 12 inches thick, in Russell formation (lower part of Benton division), quarried near Downs [Osborne County, north-central Kansas] and extensively used for fence posts, so that it may appropriately be called Fencepost limestone.
The signature item of central Kansas
Highest stratum of the Greenhorn is a geographically and lithologically persistent bed of tough chalky limestone that Cragin (1896, p. 49) called the Downs limestone or Fencepost limestone. The informal term "Fencepost limestone bed" has become widely popular through extensive use of the rock for fence posts, attaining stature equal to that of names of adjacent members because the unit is an excellent marker bed. The Fencepost outcrop is marked over broad areas by abandoned shallow quarries from which the rock has been excavated.
Mr. Chairman, we would recommend that rather than naming the state rock "limestone", which is prevalent in different forms around the country, we should declare a limestone specific to Kansas as the state rock. Our recommendation would be Greenhorn limestone, the famous "post rock" limestone that has the largest distribution statewide,[sic - Cottonwood and other limestones have larger distributions in the state] running from Ford County all the way to Washington County [i.e., Smoky Hills ], and can be seen as fenceposts everywhere in between.
… but some evidence suggests that shiners are less resistant to weather. Shiners allowed fossils to be visible on the face, but some evidence suggests that shiners are less resistant to weather
This church [St. Fedelis] is probably the best known stone church in western Kansas. … The latter [Fencepost Limestone] was particularly popular because it was easily accessible and had a thickness of about eight inches. It was an ideal ledge to quarry and lay before the days of modern machinery. … The Fort Hays Limestone should only be used in relatively arid climates because the stone is very susceptible to deterioration by moisture. Hence, its use is restricted to the dry western portions of Kansas.
… also found in the lowermost part of the Fairport ….
[Shellrock] The more desirable "fence post" limestone bed is not widely exposed in Cloud County, so beds in the Jetmore are quarried instead. … It is gray or white in color. It has been used in fences, bridges, foundations and even in buildings
When onsite restoration is not possible, we dismantle/reclaim the material to be re-used in a new environment.
We provide stone for … building, paving, landscaping.
At the beginning of this niche business, the Vonada's started engraving names on the 100-year- old-fence post. Soon they added many other signs, monuments, and garden fixtures, such as birdbaths, sundial mounts and stone benches. / The Vonada's accommodate tour groups who wish to see how the stone is quarried out using the tools of a hundred years ago. / Vonada Stone Company sign. / Vonada Stone signs can be seen throughout the state proudly bearing a family name. .
Greenhorn: ... the top [e.g., Fencepost limestone] is a good marker on gamma-ray and resistivity logs.
Maximum transgression (Fig. 22) is represented by relatively pure pelagic carbonates of the Jetmore and Pfeifer Members of the Greenhorn; for this reason the sequence was named Greenhorn cyclothem by Hattin (1962, p. 124).
Figure 4. A. Typical exposure of Jetmore equivalent, Bridge Creek Limestone Member in field-conference area, showing rhythmic alternations of thin bioturbated limestones and thicker marly shales.
The hills in the middle are capped with limestone. This area of the Smoky Hills is known as post-rock country. Because wood was scarce, early farmers quarried limestone to use as fence posts.
Originally, the geologic interval between the Dakota Sandstone and the Niobrara Formation in Kansas was designated the Fort Benton Group by Meek and Hayden (1862). … Thus the stratigraphic assignments of marine vertebrate specimens from Cenomanian and Turonian deposits of the mid-continent prior to the 1930s are generally referred to as being from the Fort Benton, or Benton Cretaceous.
Furthermore, no significant paleontological change occurs at this stratigraphic position. Major elements of the Pfeifer fauna occur also in at least the lower few feet of the Fairport Member of the Carlile Shale. These forms are: Mytiloides labiatus (Schlotheim) var., Inoceramus cuvieri Sowerby, Collignoniceras woollgari (Mantell), Baculites cf. B. yokoyamai Tokunaga and Shizimu, and Pseudoperna bentonensis (Logan). It seems obvious that the contact as presently defined cannot (and should not) be defended on paleontological grounds. ... Lithology of the upper part of the Pfeifer and lower part of the Fairport are essentially identical (Fig. 5,C,D).
The old "Fort Benton Group" is not as well expressed at the surface nor as intensely studied as the Smoky Hill Chalk badlands in western Kansas, yet it has produced nearly as many partial plesiosaur skeletons. The upper Pfeifer Shale Member, Greenhorn Limestone and the Fairport Chalk Member, Carlile Shale, in particular, have produced a significant number of pliosaurid and polycotylid skeletons. Polycotylids are especially well represented, ... Elasmosaurs were about equally as abundant as pliosaurids, ... In addition to the plesiosaurs discussed herein, we note that the Fairport Chalk preserves abundant shark remains ..., turtles ..., mosasaurs ...
In October, 2009, I chanced upon the remains of a Xiphactinus in a road cut near Wilson Lake in Russell County, Kansas.[pictured] ... The ledge above my head is the Fencepost Limestone, ...
Eight to twelve inches thick, the Fencepost limestone layer often lies very near the surface (generally no more than three feet) and outcrops abundantly through the central part of the Smoky Hills region. It is this layer for which "Post Rock Country" gained its name.
Because of the superior resistance to erosion of the Fencepost limestone bed the Pfeifer Member is exposed most commonly in the upper parts of slopes and bluffs held up by that marker.
[Pfeifer marker beds are described in the context of the Fencepost bed:] PF-1 and PF-3 are readily identified in the Pfeifer equivalent of the Bridge Creek in Hamilton County (Loc. 14), and the identification of PF-2 is reasonably certain. Of the remaining three, noncoded markers, only one, a bentonite seam lying shortly below the Fencepost bed, ...
The "Fencepost" limestone forms a conspicuous shoulder on many of the hills in the southeastern part of Jewell County
As may be seen in the section, there are a number of thin limestones in the lower part of the formation. The most prominent one occurs 17 feet above the "fence post" limestone and is approximately 5 inches thick. It varies in color from a light buff at the base to a reddish-buff at the top and so may be confused, especially when weathered, with the "fence post" limestone.
Limestone posts were also quarried from other layers within the Greenhorn limestone. ... The Shellrock bed is similar in thickness to the Post Rock, but is greyish-white in color and less consistent. There[sic] usefulness was limited, however, as they did not exhibit the strength or resistance to elements as posts from the Post Rock bed.
thin-section studies show that the chief constituents of the chalky limestone are microcrystalline calcite ooze and microsparry recrystallized calcite, which make up 45 to 85 percent of the rock... A chalky limestone marker bed (Pl. 4A) that lies 4.0 to 6.2 feet above the base of the formation contains recrystallized remains of belemnites, some of which are more than 0.5-foot in length. ... The top of the marker bed contains recrystallized belemnites?
In the Carlile shale a chalky limestone bed 4 to 5 inches thick [F-2] that occurs 5 1/2 feet above the base of the Fairport member is readily recognizable by the presence immediately below it of an orange-yellow bentonitic clay bed 5 inches thick[F-1]. At 11 feet above the base of the Fairport member is a layer of ellipsoidal chalky limestone concretions averaging about 8 inches in thickness and a foot in diameter that readily distinguishes the limestone beds that occur stratigraphically near it. The three thin beds of chalky limestone that occur in the interval from 20 to 25 feet above the base of the member and weather to a red-brown to tan color may be recognized, and are sufficiently hard to form minor benches and make useful key beds for mapping.
...but at locality 21 a bed that lies 15 feet above the base of the member is very gritty, owing to concentration of Foraminifera. / In western Russell County, a bed that lies about 19 feet above the base of the member has a conspicuous moderate reddish-orange color and has been called "pink lime" by some geologists (Rubey and Bass, 1925, p. 41). [also Plate 4. A and C]
In Ellis County, ... posts were quarried from the yellow Fort Hays chalk. Since the chalk is softer than the Post Rock layer, the posts were considerably wider and crumbled when exposed to the weather.
The Fort Hays Limestone Member of the Niobrara Chalk has been quarried for structural stone at numerous localities in Trego County. The Fort Hays is relatively soft, although it hardens upon weathering. The Fort Hays also tends to absorb water and thus to deteriorate through freeze-and-thaw action and from spalling. Many farm buildings, city dwellings, and business houses in the area constructed of the Fort Hays Limestone seem to stand up well for many years, however. In a report by Risser (1960) the sources and characteristics of building stone in Kansas are discussed.
In addition to fence posts, the [Fencepost] limestone has been used widely in southern Ellis County and elsewhere for foundations and buildings. Among the buildings constructed from this stone are the magnificent Catholic churches at Pfeifer, Victoria, and Liebenthal and the principal buildings at the Fort Hays State College in Hays. Newer buildings constructed from sawed blocks of this stone include the Methodist church and the Ellis County courthouse in Hays. ... The Fort Hays Limestone member of the Niobrara Chalk also has been quarried for structural stone, although it is not as weather-resistant as the "Fencepost" Limestone bed. It is softer than the Greenhorn Limestone and spalls badly when used for foundation stone.
Driving on I-70 across the western part of Kansas you cannot help but notice a sign welcoming you to Post Rock Country. After wondering if you have entered some strange enclave of Celine Dion partisans, you will start noticing that fence posts along the interstate are made from stone and not from wood.[ unreliable source? ]
220.6 Fencepost limestone, on frontage road north of I-70, ...
Cut on east side of U.S. Highway 183 approximately 1/2 mile northeast of Schoenchen. Upper part of Pfeifer Member.
Fairport Chalk Member [description of the lower Fairport markers]