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Wallabi Limestone
Wallabi Limestone is the name given to the dense calcretised, limestone platform that underlies the Wallabi Group of the Houtman Abrolhos, an archipelago off the coast of Western Australia. This platform, which arises abruptly from a flat shelf, is about 40 metres thick, and is of marine biogenic origin, having originated as a coral reef. It reached its maximum size during the Eemian Stage (about 125,000 years ago), when sea levels were higher than at present. The subsequent fall in sea level resulted in the reef becoming emergent in places, thus forming the basement of the group's "central platform" islands, namely West Wallabi Island, East Wallabi Island and North Island. References See also *List of types of limestone This is a list of types of limestone arranged according to location. It includes both formal stratigraphic unit names and less formal designations. Africa Egypt * Tura limestone, used for the Great Pyramid casing stones * Mokattam limestone; ... Limesto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geoscience Australia
Geoscience Australia is an agency of the Australian Government. It carries out geoscientific research. The agency is the government's technical adviser on all aspects of geoscience, and custodian of the geographic and geological data and knowledge of the nation. On a user pays basis it produces geospatial products such as topographic maps and satellite imagery. It is also a major contributor to the Australian Government's free, open data collections such as data.gov.au. Strategic priorities The agency has six strategic priority areas: # building Australia's resource wealth in order to maximise benefits from Australia's minerals and energy resources, now and into the future; # ensuring Australia's community safety so that Australian communities are more resilient to natural hazards; # securing Australia's water resources in order to optimise and sustain the use of Australia's water resources; # managing Australia's marine jurisdictions in order to maximise benefits from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eemian Stage
The Eemian (also called the last interglacial, Sangamonian Stage, Ipswichian, Mikulin, Kaydaky, penultimate,NOAA - Penultimate Interglacial Period http://www.ncdc.noaa.gov/global-warming/penultimate-interglacial-period Valdivia or Riss-Würm) was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It corresponds to Marine Isotope Stage 5e. Although sometimes referred to as the "last interglacial" (in the "most recent previous" sense of "last"), it was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day (having followed the last glacial period). The prevailing Eemian climate was, on average, around 1 to 2 degrees Celsius (1.8 to 3.6 Fahrenheit) warmer than that of the Holocene. During the Eemian, the proportion of in the atmosphere was about 280 parts per million. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geologic Formations Of Australia
Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth science, Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the Relative dating, relative and Geochronology, absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone Formations
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limestone co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Types Of Limestone
This is a list of types of limestone arranged according to location. It includes both formal stratigraphic unit names and less formal designations. Africa Egypt * Tura limestone, used for the Great Pyramid casing stones * Mokattam limestone; Great Pyramid core stones and head of the Great Sphinx are of the "Member III" stratum *Galala marble (a type of limestone, not a true marble) Asia India * * Israel (West Bank) * * Europe Austria * Belgium *, (not a "true marble"; Devonian limestone) * * Croatia * France * *, or "Paris stone" (city buildings are widely faced with it) **, or Oise, limestone (variety of Lutetian) * *, in the Loire Valley Germany * * Gibraltar * Ireland * , not a "true marble"; fossiliferous Carboniferous limestone. Italy * , not a "true marble"; fossiliferous limestone United Kingdom England: * (not a "true marble"; Carboniferous limestone) * * * , the famous London Stone is made of this. * (not a "true slate"; thin-bedded limesto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North Island (Houtman Abrolhos)
North Island is the northernmost island in the Houtman Abrolhos, a coral reef archipelago in the Indian Ocean off the coast of Mid West Western Australia. Located about 14 km (9 mi) from the nearest island group, it is one of the largest islands in the Houtman Abrolhos, and one of the few to support dune systems. It has relatively diverse flora dominated by chenopod shrubs and fauna that includes the introduced tammar wallaby, around seven species of reptile, and about 15 resident bird species. First recorded and surveyed in 1840, North Island has been a seasonal camp for western rock lobster fishermen since the beginning of the 20th century, and this remains the principal focus of human activity on the island. There is also a small amount of tourism, though for the most part it is reserved as conservation habitat for vegetation communities and rare birds. History Discovery The earliest recorded sighting of North Island occurred in May 1840, during the third surve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Wallabi Island
East Wallabi Island is an island in the Wallabi Group of the Houtman Abrolhos, located in the Indian Ocean off the west coast of mainland Australia. History East Wallabi Island played an important role in the story of the shipwreck and massacre. Following the shipwreck, a group of soldiers under the command of Wiebbe Hayes were put ashore on West Wallabi Island to search for water. The mutineers who took control of the ship left them there in the hope that they would starve or die of thirst. However, the soldiers discovered that they were able to wade to East Wallabi Island, where they eventually discovered a fresh water spring. Furthermore, West and East Wallabi Island are the only islands in the group upon which the tammar wallabi lives. Thus the soldiers had access to sources of both food and water that were unavailable to the mutineers. In the context of the ''Batavia'' mutiny and massacre, East Wallabi Island is often referred to as "High island". This was the name given it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
West Wallabi Island
West Wallabi Island is an island in the Wallabi Group of the Houtman Abrolhos, in the Indian Ocean off the west coast of mainland Australia. History West Wallabi Island was important in the story of the '' Batavia'' shipwreck and massacre. Following the shipwreck in 1629, a group of soldiers under the command of Wiebbe Hayes were put ashore there to search for water. A group of mutineers who took control of the other survivors left them there in the hope that they would starve or die of thirst. However the soldiers discovered that they could wade to East Wallabi Island, where there was a fresh water spring. Furthermore, West and East Wallabi Islands are the only islands in the group upon which the tammar wallaby lives. Thus the soldiers had access to sources of both food and water that were unavailable to the mutineers. Later the mutineers mounted a series of attacks, which the soldiers beat off. The Wiebbe Hayes Stone Fort, remnants of improvised defensive walls and stone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral Reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian. Sometimes called ''rainforests of the sea'', shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France, yet they provide a home for at least 25% of all marine species, including fish, mollusks, worms, crustaceans, echinode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcrete
Caliche () is a sedimentary rock, a hardened natural cement of calcium carbonate that binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, including in central and western Australia, in the Kalahari Desert, in the High Plains of the western United States, in the Sonoran Desert, Chihuahuan Desert and Mojave Desert of North America, and in eastern Saudi Arabia at Al-Hasa. Caliche is also known as calcrete or kankar (in India). It belongs to the duricrusts. The term ''caliche'' is Spanish and is originally from the Latin ''calx'', meaning lime. Caliche is generally light-colored, but can range from white to light pink to reddish-brown, depending on the impurities present. It generally occurs on or near the surface, but can be found in deeper subsoil deposits, as well. Layers vary from a few inches to feet thick, and multiple layers can exist in a single location. A calich ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogenic
A biogenic substance is a product made by or of life forms. While the term originally was specific to metabolite compounds that had toxic effects on other organisms, it has developed to encompass any constituents, secretions, and metabolites of plants or animals. In context of molecular biology, biogenic substances are referred to as biomolecules. They are generally isolated and measured through the use of chromatography and mass spectrometry techniques. Additionally, the transformation and exchange of biogenic substances can by modelled in the environment, particularly their transport in waterways. The observation and measurement of biogenic substances is notably important in the fields of geology and biochemistry. A large proportion of isoprenoids and fatty acids in geological sediments are derived from plants and chlorophyll, and can be found in samples extending back to the Precambrian. These biogenic substances are capable of withstanding the diagenesis process in sediment, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine (ocean)
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the world ocean is conventionally divided."Ocean." ''Merriam-Webster.com Dictionary'', Merriam-Webster, [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
