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
The evolutionary relationship between the members of the group is still debated, and their classification into loose tribes rather than formal subgroups reflects this uncertainty. General characteristics include cloven hoofs and usually at least one of the sexes of a species having true horns, the largest extant bovine is the gaur. In most countries, bovids are used for food, cattle are eaten almost everywhere except in parts of India and Nepal where they are considered sacred by most Hindus. Bos comes from the Indo-European root *gwous, meaning ox, international Commission on Zoological Nomenclature Opinion 2027. Usage of 17ΔбГ specific names based on species which are pre-dated by or contemporary with those based on domestic animals. Congress on Controversies in Bovine Health, Industry & Economics
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate. The Mohs scale of hardness, based on scratch hardness comparison. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite, aragonite will change to calcite at 380–470 °C, and vaterite is even less stable. Calcite is derived from the German Calcit, a term coined in the 19th century from the Latin word for lime and it is thus etymologically related to chalk. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, prisms, or various scalenohedra. Calcite exhibits several twinning types adding to the variety of observed forms and it may occur as fibrous, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form and its fracture is conchoidal, but difficult to obtain. It has a defining Mohs hardness of 3, a gravity of 2.71.
Color is white or none, though shades of gray, orange, green, violet, calcite is transparent to opaque and may occasionally show phosphorescence or fluorescence. A transparent variety called Iceland spar is used for optical purposes, acute scalenohedral crystals are sometimes referred to as dogtooth spar while the rhombohedral form is sometimes referred to as nailhead spar. Single calcite crystals display an optical property called birefringence and this strong birefringence causes objects viewed through a clear piece of calcite to appear doubled. The birefringent effect was first described by the Danish scientist Rasmus Bartholin in 1669, at a wavelength of ~590 nm calcite has ordinary and extraordinary refractive indices of 1.658 and 1.486, respectively. Between 190 and 1700 nm, the refractive index varies roughly between 1.9 and 1.5, while the extraordinary refractive index varies between 1.6 and 1.4. Calcite, like most carbonates, will dissolve with most forms of acid, calcite can be either dissolved by groundwater or precipitated by groundwater, depending on several factors including the water temperature, pH, and dissolved ion concentrations.
Although calcite is fairly insoluble in water, acidity can cause dissolution of calcite. Ambient carbon dioxide, due to its acidity, has a slight solubilizing effect on calcite, calcite exhibits an unusual characteristic called retrograde solubility in which it becomes less soluble in water as the temperature increases. When conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together or it can fill fractures. On a landscape scale, continued dissolution of calcium carbonate-rich rocks can lead to the expansion and eventual collapse of cave systems, high-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry
Perched only about one kilometer farther east on the opposite side of the valley is the little village of Fleurac. The country rocks of the cave are flat-lying limestones belonging to the uppermost Coniacian and these rocks together with overlying Santonian rocks form the limestone plateau of Légal, the divide between the drainage basins of the rivers Lisle and Vézère. The Rouffignac cave and the Villars cave possess the most extensive system of the Périgord with more than 8 km of underground passageways. There are 10 natural shafts that lead to a deeper level and it is astonishing that most of the artistic representations nearly always seem to be associated with these dangerous places. So far, a further 4 km of passageways have been explored in this deeper level, below the deeper level exists a bottom level with a small underground rivulet. Visitors of the cave have to board a train that takes them about 2 km into the interior. The plan of the cave reveals a fractal-like dendritic pattern that is not random, presumably the cave was formed during the Pliocene about 3 to 2 million years ago.
Water had infiltrated the bedrock along certain zones of weakness and dissolved the limestone, today this process has come to an end, the cave is mostly dry except for the rivulet along the base level. The Rouffignac cave was already mentioned in 1575 by François de Belleforest, in his Cosmographie universelle he cites “paintings and animal traces”. In the 19th century the cave was known as a tourist attraction, during the Second World War the cave had served as a hide-out for the French Résistance. In 1959 the cave was opened for visitors. In conjunction with other caves and abris of the Vézère valley the Rouffignac cave was classified a Monument historique in 1957, the cave is under private ownership. The artistic representations in the cave were executed as engravings or black contour drawings. In contrast with the caves in Lascaux and Font-de-Gaume the representations in the Rouffignac cave are not polychrome, so far 224 animal representations and 4 human figures have been registered. The animal representations can be subdivided as follows,158 mammoths, additionally there is one single cave bear.
Amongst the six animal groups cited the mammoths take on a prominent role, the woolly rhinoceros are quite common compared to other similar caves where they always appear as an absolute rarity. Signs are somewhat underrepresented with 17 tectiform and 6 serpentiform signs being known, fairly common are finger flutings, macaroni- or meander-like traces that take up a surface of 500 m2 and decorate walls and ceilings. 63 animal representations alone are found on the ceiling of the so-called Le Grand Plafond chamber, here again the representations are associated with a shaft
The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals.
Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate.
Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, South America, Australasia. As the Jurassic proceeded and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
Karst topography is a landscape formed from the dissolution of soluble rocks such as limestone and gypsum. It is characterized by underground drainage systems with sinkholes and caves and it has been documented for more weathering-resistant rocks, such as quartzite, given the right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes, the English word karst was borrowed from German Karst in the late 19th century. The German word came into use before the 19th century, according to the prevalent interpretation, the term is derived from the German name for the Karst region, a limestone plateau above the city of Trieste in the northern Adriatic. Scholars disagree, however, on whether the German word was borrowed from Slovene, the Slovene common noun kras was first attested in the 18th century, and the adjective form kraški in the 16th century. The Slovene words arose through metathesis from the reconstructed form *korsъ, the word is of Mediterranean origin, believed to derive from some Romanized Illyrian base.
It has been suggested that the word may derive from the Proto-Indo-European root karra- rock, the name may be connected to the oronym Karsádios oros cited by Ptolemy, and perhaps to Latin Carusardius. The development of karst occurs whenever acidic water starts to break down the surface of bedrock near its cracks, as the bedrock continues to degrade, its cracks tend to get bigger. As time goes on, these fractures will become wider, if this underground drainage system does form, it will speed up the development of karst formations there because more water will be able to flow through the region, giving it more erosive power. The carbonic acid that causes karstic features is formed as rain passes through the atmosphere picking up carbon dioxide, once the rain reaches the ground, it may pass through soil that can provide much more CO2 to form a weak carbonic acid solution, which dissolves calcium carbonate. The oxidation of sulfides leading to the formation of acid can be one of the corrosion factors in karst formation.
As oxygen -rich surface waters seep into deep anoxic karst systems, they bring oxygen, sulfuric acid reacts with calcium carbonate, causing increased erosion within the limestone formation. This chain of reactions is, This reaction chain forms gypsum, the karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath. On exposed surfaces, small features may include solution flutes, limestone pavement, medium-sized surface features may include sinkholes or cenotes, vertical shafts, disappearing streams, and reappearing springs. Large-scale features may include limestone pavements and karst valleys, mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers, or haystack/eggbox landscapes. Beneath the surface, complex underground systems and extensive caves. Some of the most dramatic of these formations can be seen in Thailands Phangnga Bay, calcium carbonate dissolved into water may precipitate out where the water discharges some of its dissolved carbon dioxide.
Rivers which emerge from springs may produce tufa terraces, consisting of layers of calcite deposited over extended periods of time, in caves, a variety of features collectively called speleothems are formed by deposition of calcium carbonate and other dissolved minerals
The cave bear was a species of bear that lived in Europe and Asia during the Pleistocene and became extinct about 24,000 years ago during the Last Glacial Maximum. Both the word cave and the scientific name spelaeus are used because fossils of species were mostly found in caves. This reflects the views of experts that cave bears may have spent more time in caves than the brown bear, Cave bear skeletons were first described in 1774 by Johann Friederich Esper in his book Newly Discovered Zoolites of Unknown Four Footed Animals. While scientists at the time considered that the skeletons could belong to apes, felids, or even dragons or unicorns, twenty years later, Johann Christian Rosenmüller, an anatomist at the Leipzig University, gave the species its binomial name. The bones were so numerous that most researchers had little regard for them, during World War I, with the scarcity of phosphate dung, earth from the caves where cave bear bones occurred were used as a source of phosphates. When the dragon caves in Austrias Steiermark region were exploited for this purpose, only the skulls, many caves in Central Europe have skeletons of cave bears inside, for example the Heinrichshöhle in Hemer, the Dechenhöhle in Iserlohn, Germany.
A complete skeleton, five complete skulls, and 18 other boness were found inside Jaskinia Niedźwiedzia in 1966 in Poland, in Romania, in a cave called Bears Cave,140 cave bear skeletons were discovered in 1983. Both the cave bear and the bear are thought to be descended from the Plio-Pleistocene Etruscan bear that lived about 5.3 Mya to 10,000 years ago. The last common ancestor of cave bears and brown bears lived between 1.2 and 1.4 Mya. The immediate precursor of the bear was probably Ursus deningeri. Ursus spelaeus deningeroides, while other authorities consider both taxa to be variants of the same species. Cave bears found in different regions vary in age, thus facilitating investigations into evolutionary trends, the three anterior premolars were gradually reduced, possibly in response to a largely vegetarian diet. In a fourth of the found in the Conturines, the third premolar is still present. The last remaining premolar became conjugated with the molars, enlarging the crown and granting it more cusps.
This phenomenon, known as molarization, improved the mastication capacities of the molars and this allowed the cave bear to gain more energy for hibernation, while eating less than its ancestors. The cave bear had a broad, domed skull with a steep forehead. Its stout body had long thighs, massive shins and in-turning feet, Cave bears were comparable in size to the largest modern-day bears. The average weight for males was 400 to 500 kilograms, with a specimen weighing 817 kg or more
The horse is one of two extant subspecies of Equus ferus. It is an ungulate mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature, into the large, humans began to domesticate horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC. Horses in the subspecies caballus are domesticated, although some domesticated populations live in the wild as feral horses. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, colors, breeds and behavior. Horses anatomy enables them to use of speed to escape predators and they have a well-developed sense of balance. Related to this need to flee from predators in the wild is an unusual trait, female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in harness between the ages of two and four and they reach full adult development by age five, and have an average lifespan of between 25 and 30 years.
There are more than 300 breeds of horse in the world today, horses were historically used in warfare, from which a wide variety of riding and driving techniques developed, using many different styles of equipment and methods of control. Many products are derived from horses, including meat, hide, bone, humans provide domesticated horses with food and shelter, as well as attention from specialists such as veterinarians and farriers. Specific terms and specialized language are used to describe equine anatomy, different life stages, depending on breed and environment, the modern domestic horse has a life expectancy of 25 to 30 years. Uncommonly, a few animals live into their 40s and, the oldest verifiable record was Old Billy, a 19th-century horse that lived to the age of 62. In modern times, Sugar Puff, who had listed in Guinness World Records as the worlds oldest living pony. The exception is in endurance riding, where the age to compete is based on the animals actual calendar age. The following terminology is used to describe horses of various ages, Colt, a common terminology error is to call any young horse a colt, when the term actually only refers to young male horses.
Filly, A female horse under the age of four, foal, A horse of either sex less than one year old. A nursing foal is sometimes called a suckling and a foal that has been weaned is called a weanling, most domesticated foals are weaned at five to seven months of age, although foals can be weaned at four months with no adverse physical effects. Gelding, A castrated male horse of any age, mare, A female horse four years old and older
A stalagmite is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites may be composed of amberat, minerals, peat, sand, the corresponding formation hanging down from the ceiling of a cave is a stalactite. Mnemonics have been developed for which word refers to type of formation, one is that stalactite has a C for ceiling. The most common stalagmites are speleothems, which form in limestone caves. This stalagmite formation occurs only under certain pH conditions within the underground cavern and they form through deposition of calcium carbonate and other minerals, which is precipitated from mineralized water solutions. Limestone is the form of calcium carbonate rock, which is dissolved by water that contains carbon dioxide. If stalactites – the ceiling formations – grow long enough to connect with stalagmites on the floor and dirt from human contact can stain the formation and change its color permanently.
Another type of stalagmite is formed in lava tubes while lava is still active inside, the mechanism of formation is similar to that of limestone stalagmites. A key difference with lava stalagmites is that once the lava has ceased flowing and this means if the stalagmite were to be broken it would never grow back. Stalagmites in lava tubes are rarer than their stalactite counterparts because during formation the dripping material falls onto still-moving lava floors that absorb or carry the material away, the generic term lavacicle has been applied to lava stalactites and stalagmites indiscriminately, and evolved from the word icicle. A common stalagmite found seasonally or year round in many caves is the ice stalagmite, commonly referred to as icicles, water seepage from the surface will penetrate into a cave and if temperatures are below freezing temperature, the water will collect on the floor into stalagmites. Deposition may directly from the freezing of water vapor. Similar to lava stalagmites, ice stalagmites form very quickly within hours or days, unlike lava stalagmites however, they may grow back as long as water and temperatures are suitable.
Ice stalagmites are more common than their stalactite counterparts because warmer air rises to the ceilings of caves, ice stalactites may form corresponding stalagmites below them, and given time, may grow together to form an ice column. Stalactites and stalagmites can form on concrete ceilings and floors, calcium carbonate deposition as a stalagmite occurs when the solution carries the calcium laden leachate solution to the ground under the concrete structure. Carbon dioxide is absorbed into the alkaline solution, which facilitates the chemical reactions to deposit calcium carbonate as a stalagmite. These stalagmites rarely grow taller than a few centimetres, secondary deposits, which create stalagmites, flowstone etc, outside the natural cave environment, are referred to as “calthemites”. These concrete derived secondary deposits can’t be referred to as “speleothems” due to the definition of the word, the largest known stalagmite in the world exceeds 70 metres in height and is located in Sơn Đoòng Cave, Vietnam
The Upper Paleolithic is the third and last subdivision of the Paleolithic or Old Stone Age. Very broadly, it dates to between 50,000 and 10,000 years ago, roughly coinciding with the appearance of behavioral modernity, modern humans are believed to have emerged about 195,000 years ago in Africa. Although these humans were modern in anatomy, their lifestyle changed very little from their contemporaries, such as Homo erectus, about 50,000 years ago, there was a marked increase in the diversity of artifacts. In Africa, bone artifacts and the first art appear in the archeological record, between 45,000 and 43,000 years ago, this new tool technology spread with human migration to Europe. The new technology generated an explosion of modern humans which is believed to have contributed to the extinction of the Neanderthals. The Upper Paleolithic has the earliest known evidence of organized settlements, in the form of campsites, artistic work blossomed, with cave painting, petroglyphs and engravings on bone or ivory.
The first evidence of fishing is noted, from artifacts in places such as Blombos cave in South Africa. More complex social groupings emerged, supported by more varied and reliable food sources and this probably contributed to increasing group identification or ethnicity. By 50, 000–40,000 BP, the first humans set foot in Australia, by 45,000 BP, humans lived at 61° north latitude in Europe. By 30,000 BP, Japan was reached, and by 27,000 BP humans were present in Siberia above the Arctic Circle, at the end of the Upper Paleolithic, a group of humans crossed the Bering land bridge and quickly expanded throughout North and South America. Both Homo erectus and Neanderthals used the same crude stone tools, archaeologist Richard G. Klein, who has worked extensively on ancient stone tools, describes the stone tool kit of archaic hominids as impossible to categorize. It was as if the Neanderthals made stone tools, and were not much concerned about their final forms and he argues that almost everywhere, whether Asia, Africa or Europe, before 50,000 years ago all the stone tools are much alike and unsophisticated.
These new stone-tool types have been described as being distinctly differentiated from each other, the invaders, commonly referred to as the Cro-Magnons, left many sophisticated stone tools and engraved pieces on bone and antler, cave paintings and Venus figurines. The Neanderthals continued to use Mousterian stone tool technology and possibly Chatelperronian technology and these tools disappeared from the archeological record at around the same time the Neanderthals themselves disappeared from the fossil record, about 40,000 years ago. Settlements were often located in valley bottoms, possibly associated with hunting of passing herds of animals. Hunting was important, and caribou/wild reindeer may well be the species of single greatest importance in the anthropological literature on hunting. Technological advances included significant developments in flint tool manufacturing, with industries based on fine blades rather than simpler and shorter flakes and racloirs were used to work bone and hides.
Advanced darts and harpoons appear in period, along with the fish hook, the oil lamp, rope