Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine.
Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, granular, or massive, depending on the method of formation.
Crystals of calcite, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
Kentucky, officially the Commonwealth of Kentucky, is a state located in the east south-central region of the United States. Kentucky is one of four U. S. states constituted as a commonwealth, originally a part of Virginia, in 1792 Kentucky became the 15th state to join the Union. Kentucky is the 37th most extensive and the 26th most populous of the 50 United States, Kentucky is known as the Bluegrass State, a nickname based on the bluegrass found in many of its pastures due to the fertile soil. One of the regions in Kentucky is the Bluegrass Region in central Kentucky. In 1776, the counties of Virginia beyond the Appalachian Mountains became known as Kentucky County, the precise etymology of the name is uncertain, but likely based on an Iroquoian name meaning the meadow or the prairie. Kentucky is situated in the Upland South, a significant portion of eastern Kentucky is part of Appalachia. Kentucky borders seven states, from the Midwest and the Southeast, West Virginia lies to the east, Virginia to the southeast, Tennessee to the south, Missouri to the west and Indiana to the northwest, and Ohio to the north and northeast.
Only Missouri and Tennessee, both of which border eight states, touch more, Kentuckys northern border is formed by the Ohio River and its western border by the Mississippi River. The official state borders are based on the courses of the rivers as they existed when Kentucky became a state in 1792, for instance, northbound travelers on U. S.41 from Henderson, after crossing the Ohio River, will be in Kentucky for about two miles. Ellis Park, a racetrack, is located in this small piece of Kentucky. Waterworks Road is part of the land border between Indiana and Kentucky. Kentucky has a part known as Kentucky Bend, at the far west corner of the state. It exists as an exclave surrounded completely by Missouri and Tennessee, Road access to this small part of Kentucky on the Mississippi River requires a trip through Tennessee. The epicenter of the powerful 1811–12 New Madrid earthquakes was near this area, much of the outer Bluegrass is in the Eden Shale Hills area, made up of short and very narrow hills.
The Jackson Purchase and western Pennyrile are home to several bald cypress/tupelo swamps, located within the southeastern interior portion of North America, Kentucky has a climate that can best be described as a humid subtropical climate. Temperatures in Kentucky usually range from daytime summer highs of 87 °F to the low of 23 °F. The average precipitation is 46 inches a year, Kentucky experiences four distinct seasons, with substantial variations in the severity of summer and winter. The highest recorded temperature was 114 °F at Greensburg on July 28,1930 while the lowest recorded temperature was −37 °F at Shelbyville on January 19,1994, due to its location, Kentucky has a moderate humid subtropical climate, with abundant rainfall
Stratigraphy is a branch of geology which studies rock layers and layering. It is primarily used in the study of sedimentary and layered volcanic rocks, stratigraphy has two related subfields, lithologic stratigraphy or lithostratigraphy, and biologic stratigraphy or biostratigraphy. The first practical application of stratigraphy was by William Smith in the 1790s. Another influential application of stratigraphy in the early 19th century was a study by Georges Cuvier, variation in rock units, most obviously displayed as visible layering, is due to physical contrasts in rock type. This variation can occur vertically as layering, or laterally, and these variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit. Key concepts in stratigraphy involve understanding how certain geometric relationships between rock layers arise and what these geometries imply about their original depositional environment. The basic concept in stratigraphy, called the law of superposition, states, in a stratigraphic sequence.
Chemostratigraphy studies the changes in the proportions of trace elements and isotopes within. Carbon and oxygen isotope ratios vary with time, and researchers can use those to map subtle changes that occurred in the paleoenvironment and this has led to the specialized field of isotopic stratigraphy. Biostratigraphy or paleontologic stratigraphy is based on evidence in the rock layers. Strata from widespread locations containing the fossil fauna and flora are said to be correlatable in time. Biologic stratigraphy was based on William Smiths principle of succession, which predated. It provides strong evidence for the formation and extinction of species, the geologic time scale was developed during the 19th century, based on the evidence of biologic stratigraphy and faunal succession. One important development is the Vail curve, which attempts to define a global historical sea-level curve according to inferences from worldwide stratigraphic patterns, stratigraphy is commonly used to delineate the nature and extent of hydrocarbon-bearing reservoir rocks and traps of petroleum geology.
Chronostratigraphy is the branch of stratigraphy that places an absolute age, a gap or missing strata in the geological record of an area is called a stratigraphic hiatus. This may be the result of a halt in the deposition of sediment, the gap may be due to removal by erosion, in which case it may be called a stratigraphic vacuity. It is called a hiatus because deposition was on hold for a period of time, a physical gap may represent both a period of non-deposition and a period of erosion. A geologic fault may cause the appearance of a hiatus, magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences
Mammoth Cave National Park
Mammoth Cave National Park is a U. S. national park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. Since the 1972 unification of Mammoth Cave with the system under Flint Ridge to the north. The park was established as a park on July 1,1941. It became a World Heritage Site on October 27,1981, the parks 52,830 acres are located primarily in Edmonson County, with small areas extending eastward into Hart County and Barren County. It is centered on the Green River, with a tributary, with 405 miles of surveyed passageways Mammoth Cave is by far the worlds longest known cave system, being over twice as long as the second-longest cave system, Mexicos Sac Actun underwater cave. Mammoth Cave developed in thick Mississippian-aged limestone strata capped by a layer of sandstone and it is known to include more than 390 miles of passageway, new discoveries and connections add several miles to this figure each year. Mammoth Cave National Park was established to preserve the cave system, the epikarstic zone concentrates local flows of runoff into high-elevation springs which emerge at the edges of ridges.
It is in underlying massive limestone layers that the human-explorable caves of the region have naturally developed. The limestone layers of the column beneath the Big Clifty, in increasing order of depth below the ridgetops, are the Girkin Formation. Genevieve Limestone, and the St. Louis Limestone, for example, the large Main Cave passage seen on the Historic Tour is located at the bottom of the Girkin and the top of the Ste. Each of the layers of limestone is divided further into named geological units and subunits. One area of research involves correlating the stratigraphy with the cave survey produced by explorers. This makes it possible to produce approximate three-dimensional maps of the contours of the layer boundaries without the necessity for test wells. The upper sandstone caprock is relatively hard for water to penetrate, the sandstone caprock layer has been dissolved and eroded at many locations within the park, such as the Frozen Niagara room. At one valley bottom in the region of the park.
Known as Cedar Sink, the features a small river entering one side. Mammoth Cave is home to the endangered Kentucky cave shrimp, a sightless albino shrimp, the National Park Service offers several cave tours to visitors. Some notable features of the cave, such as Grand Avenue, Frozen Niagara, two tours, lit only by visitor-carried paraffin lamps, are popular alternatives to the electric-lit routes
A formation or geological formation is the fundamental unit of lithostratigraphy. A formation consists of a number of rock strata that have a comparable lithology. Formations are not defined on the thickness of the strata they consist of. The concept of formally defined layers or strata is central to the discipline of stratigraphy. Formations can be divided into members and are themselves frequently parcelled together in groups, the definition and recognition of formations allow geologists to correlate geologic strata across wide distances between outcrops and exposures of rock strata. Formations were initially described to be the essential geologic time markers based on relative ages, the divisions of the geological time scale were the formations described and put in chronological order by the geologists and stratigraphers of the 18th and 19th centuries. Geologic formations are sedimentary rock layers, but may be metamorphic rocks. Igneous intrusive rocks are not divided into formations. Formations are the only formal lithostratigraphic units into which the stratigraphic column everywhere should be divided completely on the basis of lithology, Formations must be able to be delineated at the scale of geologic mapping practiced in the region.
The thickness of formations may range from less than a meter to several thousand meters, geologic formations are typically named for the geographic area in which they were first described. Strictly, formations cannot be defined on any other criteria except primary lithology, sequence stratigraphy is a concept which challenges the idea of strict lithostratigraphic units by defining units based on events in sedimentary basins such as oceanic regressions and transgressions. The term formation is used informally to refer to a specific grouping of rocks. Formation is used informally to describe the sometimes odd shapes that rocks acquire through erosional or depositional processes, such a formation is said to be abandoned when it is no longer affected by the geologic agent that produced it. Some well known cave formations include stalactites and stalagmites, geochronology List of Rock Formations List of Chinese geological formations List of fossil sites