Calcium carbonate is a chemical compound with the formula CaCO3. It is a substance found in rocks as the minerals calcite and aragonite and is the main component of pearls and the shells of marine organisms, snails. Calcium carbonate is the ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a supplement or as an antacid. Calcium carbonate shares the properties of other carbonates. CaCO3 + CO2 + H2O → Ca2 This reaction is important in the erosion of rock, forming caverns. An unusual form of calcium carbonate is the hexahydrate, ikaite is stable only below 6 °C. The vast majority of calcium used in industry is extracted by mining or quarrying. Pure calcium carbonate, can be produced from a quarried source. Alternatively, calcium carbonate is prepared from calcium oxide, other forms can be prepared, the denser, orthorhombic λ-CaCO3 and μ-CaCO3, occurring as the mineral vaterite. The aragonite form can be prepared by precipitation at temperatures above 85 °C, calcite contains calcium atoms coordinated by 6 oxygen atoms, in aragonite they are coordinated by 9 oxygen atoms.
The vaterite structure is not fully understood, magnesium carbonate MgCO3 has the calcite structure, whereas strontium and barium carbonate adopt the aragonite structure, reflecting their larger ionic radii. Calcite and vaterite are pure calcium carbonate minerals, industrially important source rocks which are predominantly calcium carbonate include limestone, chalk and travertine. Eggshells, snail shells and most seashells are predominantly calcium carbonate, oyster shells have enjoyed recent recognition as a source of dietary calcium, but are a practical industrial source. While not practical as a source, dark green vegetables such as broccoli. Beyond Earth, strong evidence suggests the presence of Calcium carbonate on Mars, signs of Calcium Carbonate have been detected at more than one location. This provides some evidence for the past presence of liquid water, Carbonate is found frequently in geologic settings and constitute an enormous carbon reservoir. Calcium carbonate occurs as aragonite and dolomite, the carbonate minerals form the rock types, chalk, travertine and others
An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the layer was exposed to erosion for an interval of time before deposition of the younger. The significance of angular unconformity was shown by James Hutton, who found examples of Huttons Unconformity at Jedburgh in 1787, the rocks above an unconformity are younger than the rocks beneath. An unconformity represents time during which no sediments were preserved in a region, the local record for that time interval is missing and geologists must use other clues to discover that part of the geologic history of that area. The interval of time not represented is called a hiatus. A disconformity is an unconformity between parallel layers of rocks which represents a period of erosion or non-deposition. Disconformities are marked by features of subaerial erosion and this type of erosion can leave channels and paleosols in the rock record. A paraconformity is a type of disconformity in which the separation is a simple bedding plane with no obvious buried erosional surface. A nonconformity exists between sedimentary rocks and metamorphic or igneous rocks when the rock lies above and was deposited on the pre-existing.
Namely, if the rock below the break is igneous or has lost its bedding due to metamorphism, the whole sequence may be deformed and tilted by further orogenic activity. A typical case history is presented by the evolution of the Briançonnais realm during the Jurassic. A paraconformity is a type of unconformity in which strata are parallel, there is no apparent erosion and it is called nondepositional unconformity or pseudoconformity. A buttress unconformity occurs when younger bedding is deposited against older strata thus influencing its bedding structure. S, bureau of Mines Dictionary of Mining and Related Terms published on CD-ROM in 1996
Zealand is the largest and most populated island in Denmark with a population of 2,267,659. It is the 96th-largest island in the world by area and the 35th most populous and it is connected to Funen by the Great Belt Fixed Link, to Lolland, Falster by the Storstrøm Bridge and the Farø Bridges. Zealand is linked to Amager by five bridges, Zealand is linked indirectly, through intervening islands by a series of bridges and tunnels, to southern Sweden. Copenhagen, the capital of Denmark, is located partly on the shore of Zealand. Other cities on Zealand include Roskilde, Hillerød, Næstved and Helsingør, the island is not connected historically to the Pacific nation of New Zealand, which is named after the Dutch province of Zeeland. In Norse mythology as told in the story of Gylfaginning, the island was created by the goddess Gefjun after she tricked Gylfi and she removed a piece of land and transported it to Denmark, which became Zealand. The vacant area was filled with water and became Mälaren, since modern maps show a similarity between Zealand and the Swedish lake Vänern, it is sometimes identified as the hole left by Gefjun.
Zealand is the most populous Danish island and it is irregularly shaped, and is north of the islands of Lolland, and Møn. The small island of Amager lies immediately east, Copenhagen is mostly on Zealand but extends across northern Amager. A number of bridges and the Copenhagen Metro connect Zealand to Amager, Zealand is joined in the west to Funen, by the Great Belt Fixed Link, and Funen is connected by bridges to the countrys mainland, Jutland. Gyldenløveshøj, south of the city Roskilde, has a height of 126 metres, Zealand gives its name to the Selandian era of the Paleocene. Urban areas with 10, 000+ inhabitants, North Zealand Media related to Zealand at Wikimedia Commons Zealand travel guide from Wikivoyage
Global Boundary Stratotype Section and Point
The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes, hence GSSPs are usually described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977, as of 2012,64 of the 101 stages that need a GSSP have been formally defined. A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS, the following list summarizes the criteria, A GSSP has to define the lower boundary of a geologic stage. The lower boundary has to be defined using a primary marker, there should be secondary markers. The horizon in which the marker appears should have minerals that can be radiometrically dated, the marker has to have regional and global correlation in outcrops of the same age The marker should be independent of facies. The Precambrian-Cambrian boundary GSSP at Fortune Head, Newfoundland is a typical GSSP and it is accessible by paved road and is set aside as a nature preserve.
A continuous section is available from beds that are clearly Precambrian into beds that are clearly Cambrian, the boundary is set at the first appearance of a complex trace fossil Treptichnus pedum that is found worldwide. The Fortune Head GSSP is unlikely to be washed away or built over. Nonetheless, Treptichnus pedum is less than ideal as a fossil as it is not found in every Cambrian sequence. In fact, further eroding its value as a boundary marker, however, no other fossil is known that would be preferable. There is no radiometrically datable bed at the boundary at Fortune Head and these factors have led some geologists to suggest that this GSSP is in need of reassigning. Once a GSSP boundary has been agreed upon, a spike is driven into the geologic section to mark the precise boundary for future geologists. GSSPs are referred to as Golden Spikes. Because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, before 630 million years ago, boundaries on the geologic timescale are defined simply by reference to fixed dates, known as Global Standard Stratigraphic Ages.
Body form European Mammal Neogene Fauna Geologic time scale New Zealand geologic time scale List of GSSPs North American Land Mammal Age Type locality Hedberg, H. D
It includes oceanic crust extending westward to the Mid-Atlantic Ridge and northward to the Gakkel Ridge. The eastern side is a boundary with the North American Plate to the north and a boundary with the Philippine Sea Plate to the south, and possibly with the Okhotsk Plate and the Amurian Plate. The southerly side is a boundary with the African Plate to the west, the Arabian Plate in the middle, the westerly side is a divergent boundary with the North American Plate forming the northernmost part of the Mid-Atlantic Ridge, which is straddled by Iceland. The geodynamics of central Asia is dominated by the interaction between the Eurasian and Indian Plates, in this area, many subplates or crust blocks have been recognized, which form the Central Asian and the East Asian transit zones
The Labrador Sea is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland. The sea is flanked by continental shelves to the southwest, northwest and it connects to the north with Baffin Bay through the Davis Strait. It has been described as a sea of the Atlantic. The sea formed upon separation of the North American Plate and Greenland Plate that started about 60 million years ago, the Labrador Sea formed upon separation of the North American Plate and Greenland Plate that started about 60 million years ago and stopped about 40 million years ago. A sedimentary basin, which is now buried under the continental shelves, onset of magmatic sea-floor spreading was accompanied by volcanic eruptions of picrites and basalts in the Paleocene at the Davis Strait and Baffin Bay. Between about 500 BC and 1300 AD, the southern coast of the sea contained Dorset and Inuit settlements, the International Hydrographic Organization defines the limits of the Labrador Sea as follows, On the North, the South limit of Davis Strait.
On the East, a line from Cape St. Francis 47°45′N 52°27′W to Cape Farewell, thence a line joining this ledge with the East extreme of Cape St. Charles in Labrador. The Labrador Sea is about 3,400 m deep and 1,000 km wide where it joins the Atlantic Ocean and it becomes shallower, to less than 700 m towards Baffin Bay and passes into the 300 kilometres wide Davis Strait. A 100–200 m deep turbidity current channel system, which is about 2–5 km wide and 3,800 kilometres long, runs on the bottom of the sea and it is called the Northwest Atlantic Mid-Ocean Channel and is one of the worlds longest drainage systems of Pleistocene age. It appears as a river bed with numerous tributaries and is maintained by high-density turbidity currents flowing within the levees. The water temperature varies between −1 °C in winter and 5–6 °C in summer, the salinity is relatively low, at 31–34.9 parts per thousand. Two-thirds of the sea is covered in ice in winter, tides are semi-diurnal, reaching 4 m. There is a water circulation in the sea.
It is initiated by the East Greenland Current and continued by the West Greenland Current, the Baffin Island Current and Labrador Current transport cold and less saline water southward along the Canadian coast. These currents carry numerous icebergs and therefore hinder navigation and exploration of the gas fields beneath the sea bed. The speed of the Labrador current is typically 0. 3–0.5 m/s, the Labrador Current maintains the water temperature at 0 °C and salinity between 30 and 34 parts per thousand. The NADW consists of three parts of different origin and salinity, and the top one, the Labrador Sea Water, is formed in the Labrador Sea. This part occurs at a depth and has a relatively low salinity, low temperature and high oxygen content compared to the layers above
The Paleocene or Palaeocene, the old recent, is a geologic epoch that lasted from about 66 to 56 million years ago. It is the first epoch of the Paleogene Period in the modern Cenozoic Era, as with many geologic periods, the strata that define the epochs beginning and end are well identified, but the exact ages remain uncertain. The Paleocene Epoch brackets two major events in Earths history and it started with the mass extinction event at the end of the Cretaceous, known as the Cretaceous–Paleogene boundary. This was a marked by the demise of non-avian dinosaurs, giant marine reptiles and much other fauna. The die-off of the dinosaurs left unfilled ecological niches worldwide, the Paleocene ended with the Paleocene–Eocene Thermal Maximum, a geologically brief interval characterized by extreme changes in climate and carbon cycling. The name Paleocene comes from Ancient Greek and refers to the old new fauna that arose during the epoch. The K–Pg boundary that marks the separation between Cretaceous and Paleocene is visible in the record of much of the Earth by a discontinuity in the fossil fauna.
There is evidence of abrupt changes in flora and fauna. There is some evidence that a substantial but very short-lived climatic change may have happened in the early decades of the Paleocene. The end of the Paleocene was marked by a time of major change, the Paleocene–Eocene Thermal Maximum upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and a major turnover in mammals on land. The Paleocene is divided into three stages, the Danian, the Selandian and the Thanetian, as shown in the table above, the Paleocene is divided into six Mammal Paleogene zones. The early Paleocene was cooler and dryer than the preceding Cretaceous, in many ways, the Paleocene continued processes that had begun during the late Cretaceous Period. During the Paleocene, the continued to drift toward their present positions. The Laramide orogeny of the late Cretaceous continued to uplift the Rocky Mountains in the American west, africa was heading north towards Europe, slowly closing the Tethys Ocean, and India began its migration to Asia that would lead to a tectonic collision and the formation of the Himalayas.
The inland seas in North America and Europe had receded by the beginning of the Paleocene, making way for new land-based flora, warm seas circulated throughout the world, including the poles. The earliest Paleocene featured a low diversity and abundance of marine life, tropical conditions gave rise to abundant marine life, including coral reefs. With the demise of marine reptiles at the end of the Cretaceous, at the end of the Cretaceous, the ammonites and many species of foraminifera became extinct. Marine fauna came to resemble modern fauna, with only the marine mammals, terrestrial Paleocene strata immediately overlying the K–Pg boundary is in places marked by a fern spike, a bed especially rich in fern fossils
The Maastrichtian is, in the ICS geologic timescale, the latest age of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned the interval from 72.1 to 66 million years ago, the Maastrichtian was preceded by the Campanian and succeeded by the Danian. At the end of period, there was a mass extinction known as the Cretaceous–Paleogene extinction event. At this extinction event, many commonly recognized groups such as dinosaurs and mosasaurs, as well as many other lesser-known groups. The cause of the extinction is most commonly linked to an asteroid about 10 kilometres wide colliding with Earth at the end of the Cretaceous. The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849 and these strata are now classified as the Maastricht Formation - both formation and stage derive their names from the city. The Maastricht Formation is known for its fossils from this age, most notably those of the giant sea reptile Mosasaurus, the base of the Maastrichtian stage is at the first appearance of ammonite species Pachydiscus neubergicus.
At the original type locality near Maastricht, the record was found to be incomplete. A reference profile for the base was appointed in a section along the Ardour river called Grande Carrière, the Maastrichtian is commonly subdivided into two substages and three ammonite biozones. The following are summaries of the characteristics of specific Maastrichtian aged formations, the Bearpaw Formation, called the Bearpaw Shale, is a sedimentary rock formation found in northwestern North America. It is exposed in the U. S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, east of the Rocky Mountains. It overlies the older Two Medicine, Judith River and Dinosaur Park Formations, and is in turn overlain by the Horseshoe Canyon Formation in Canada, to the east and south it blends into the Pierre Shale. Other fossils found in this include many types of shellfish, bony fish, rays, birds. The occasional dinosaur remains have discovered, presumably from carcasses washed out to sea.
The Hell Creek Formation is an intensely studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The Hell Creek Formation occurs in badlands of eastern Montana and portions of North Dakota, South Dakota, in Montana, the Hell Creek Formation overlies the Fox Hills Formation and is the uppermost formation of the Cretaceous period. The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230 m in depth and it is Late Campanian to Early Maastrichtian in age and is composed of mudstone and carbonaceous shales. There are a variety of environments, which have yielded a diversity of fossil material, the Horseshoe Canyon Formation outcrops extensively in the area of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, and in the city of Edmonton
The term Danish Realm refers to the relationship between Denmark proper, the Faroe Islands and Greenland—three countries constituting the Kingdom of Denmark. The legal nature of the Kingdom of Denmark is fundamentally one of a sovereign state. The Faroe Islands and Greenland have been part of the Crown of Denmark since 1397 when the Kalmar Union was ratified, legal matters in The Danish Realm are subject to the Danish Constitution. Beginning in 1953, state law issues within The Danish Realm has been governed by The Unity of the Realm, a less formal name for The Unity of the Realm is the Commonwealth of the Realm. In 1978, The Unity of The Realm was for the first time referred to as rigsfællesskabet. The name caught on and since the 1990s, both The Unity of The Realm and The Danish Realm itself has increasingly been referred to as simply rigsfællesskabet in daily parlance. The Danish Constitution stipulates that the foreign and security interests for all parts of the Danish Realm are the responsibility of the Danish government, the Faroes received home rule in 1948 and Greenland did so in 1979.
In 2005, the Faroes received a self-government arrangement, and in 2009 Greenland received self rule, the Danish Realms unique state of internal affairs is acted out in the principle of The Unity of the Realm. This principle is derived from Article 1 of the Danish Constitution which specifies that constitutional law applies equally to all areas of the Danish Realm, the Constitutional Act specifies that sovereignty is to continue to be exclusively with the authorities of the Realm. The language of Denmark is Danish, and the Danish state authorities are based in Denmark, the Kingdom of Denmarks parliament, with its 179 members, is located in the capital, Copenhagen. Two of the members are elected in each of Greenland and the Faroe Islands. The Government ministries are located in Copenhagen, as is the highest court, in principle, the Danish Realm constitutes a unified sovereign state, with equal status between its constituent parts. Devolution differs from federalism in that the powers of the subnational authority ultimately reside in central government.
The Self-Government Arrangements devolves political competence and responsibility from the Danish political authorities to the Faroese, the Faroese and Greenlandic authorities administer the tasks taken over from the state, enact legislation in these specific fields and have the economic responsibility for solving these tasks. The Danish government provides a grant to the Faroese and the Greenlandic authorities to cover the costs of these devolved areas. The 1948 Home Rule Act of the Faroe Islands sets out the terms of Faroese home rule, the Act states. the Faroe Islands shall constitute a self-governing community within the State of Denmark. It establishes the government of the Faroe Islands and the Faroese parliament. The Faroe Islands were previously administered as a Danish county, the Home Rule Act abolished the post of Amtmand and these powers were expanded in a 2005 Act, which named the Faroese home government as an equal partner with the Danish government
Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in northern Norway. Constituting the westernmost bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea, Spitsbergen covers an area of 39,044 km2, making it the largest island in Norway and the 36th-largest in the world. Other settlements, in addition to research outposts, are the Russian mining community of Barentsburg, the community of Ny-Ålesund. The island was first used as a base in the 17th and 18th centuries. Coal mining started at the end of the 19th century and several permanent communities were established, the Svalbard Treaty of 1920 recognized Norwegian sovereignty and established Svalbard as a free economic zone and a demilitarized zone. The Norwegian Store Norske and the Russian Arktikugol remain the mining companies. Research and tourism have become important supplementary industries, featuring among others the University Centre in Svalbard, no roads connect the settlements, instead snowmobiles and boats serve as local transport.
Svalbard Airport, Longyear provides the point of entry and exit. The island has an Arctic climate, although significantly higher temperatures than other places at the same latitude. The flora benefits from the period of midnight sun, which compensates for the polar night. Svalbard is a ground for many seabirds, and supports polar bears, reindeer. Six national parks protect the largely untouched, yet fragile environment, the island has many glaciers and fjords. Spitsbergen was named by its discoverer, the Dutch navigator Willem Barentsz, the name Spitsbergen, meaning “pointed mountains”, was at first applied to both the main island and the archipelago as a whole. In the seventeenth and eighteenth centuries, English whalers referred to the islands as Greenland, the Spitzbergen spelling was used in English during the 19th century, for instance by Beechey and the Royal Society. In 1906, the Arctic explorer Sir Martin Conway thought that the Spitzbergen spelling was incorrect, preferring Spitsbergen as he noted that the name was Dutch and this had little effect on British practice.
In 1920, the international treaty determining the fate of the islands was entitled the Spitsbergen Treaty, the islands were generally referred to in the USA as Spitsbergen from that time, although the spelling Spitzbergen was commonly used through the 20th century. Under Norwegian governance, the archipelago was named Svalbard in 1925, by the end of the 20th century, this usage had become common. The first confirmed and recorded sighting of the island by a European was by Willem Barentsz, the first good map with the east coast roughly indicated, appeared in 1623, printed by Willem Janszoon Blaeu
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Older rocks will be farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. Additionally spreading rates determine if the ridge is a fast, intermediate, as a general rule, fast ridges see spreading rate of more than 9 cm/year. Intermediate ridges have a rate of 4-9 cm/year while slow spreading ridges have a rate less than 4 cm/year. Earlier theories of continental drift were that continents ploughed through the sea, the idea that the seafloor itself moves as it expands from a central axis was proposed by Harry Hess from Princeton University in the 1960s. The theory is accepted now, and the phenomenon is known to be caused by convection currents in the asthenosphere, which is ductile, or plastic.
In the general case, sea floor spreading starts as a rift in a land mass. The process starts with heating at the base of the continental crust which causes it to become more plastic, because less dense objects rise in relation to denser objects, the area being heated becomes a broad dome. As the crust bows upward, fractures occur that gradually grow into rifts, the typical rift system consists of three rift arms at approximately 120 degree angles. These areas are named triple junctions and can be found in places across the world today. The separated margins of the continents evolve to form passive margins, Hess theory was that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge. If spreading continues past the incipient stage described above, two of the arms will open while the third arm stops opening and becomes a failed rift. As the two active rifts continue to open, eventually the continental crust is attenuated as far as it will stretch, at this point basaltic oceanic crust begins to form between the separating continental fragments.
When one of the rifts opens into the ocean, the rift system is flooded with seawater. The Red Sea is an example of a new arm of the sea, during this period of initial flooding the new sea is sensitive to changes in climate and eustasy. As a result, the new sea will evaporate several times before the elevation of the valley has been lowered to the point that the sea becomes stable. During this period of evaporation large evaporite deposits will be made in the rift valley, these deposits have the potential to become hydrocarbon seals and are of particular interest to petroleum geologists
Shetland /ˈʃɛtlənd/, called the Shetland Islands, is a subarctic archipelago that lies northeast of the island of Great Britain and forms part of Scotland, United Kingdom. The islands lie some 80 km to the northeast of Orkney and 280 km southeast of the Faroe Islands, the total area is 1,466 km2 and the population totalled 23,210 in 2012. The largest island, known simply as Mainland, has an area of 967 km2, making it the third-largest Scottish island, there are an additional 15 inhabited islands. The archipelago has a climate, a complex geology, a rugged coastline and many low. Humans have lived in Shetland since the Mesolithic period, and the earliest written references to the date back to Roman times. The early historic period was dominated by Scandinavian influences, especially Norway, when Scotland became part of the Kingdom of Great Britain in 1707, trade with northern Europe decreased. Fishing has continued to be an important aspect of the economy up to the present day, the discovery of North Sea oil in the 1970s significantly boosted Shetland economy and public sector revenues.
The local way of life reflects the Scots and Norse heritage of the isles including the Up Helly Aa fire festival, the islands have produced a variety of writers of prose and poetry, often in Shetland dialect. There are numerous areas set aside to protect the fauna and flora. The Shetland pony and Shetland Sheepdog are two well known Shetland animal breeds, other distinguished local breeds include the Shetland sheep, cow and duck. The Shetland pig, or grice, has been extinct since approximately 1930, the islands motto, which appears on the Councils coat of arms, is Með lögum skal land byggja. This Icelandic phrase is taken from the Danish 1241 Basic Law, Codex Holmiensis, and is mentioned in Njáls saga. The name of Shetland is derived from the Old Norse words, hjalt, in AD43 and 77 the Roman authors Pomponius Mela and Pliny the Elder referred to the seven islands they call Haemodae and Acmodae respectively, both of which are assumed to be Shetland. Another possible early reference to the islands is Tacitus report in AD98, after describing the discovery and conquest of Orkney.
In early Irish literature, Shetland is referred to as Inse Catt—the Isles of Cats, the Cat tribe occupied parts of the northern Scottish mainland and their name can be found in Caithness, and in the Gaelic name for Sutherland. It is possible that the Pictish cat sound forms part of this Norse name and it became Hjaltland in the 16th century. As Norn was gradually replaced by English in the form of the Shetland dialect which shares similarities with Scots English. The initial letter is the Middle Scots letter, the pronunciation of which is almost identical to the original Norn sound, /hj/