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Purbeck Stone
Purbeck stone refers to building stone taken from a series of limestone beds found in the Upper Jurassic to Lower Cretaceous Purbeck Group, found on the Isle of Purbeck, Dorset in southern England. The best known variety of this stone is Purbeck Marble. The stone has been quarried since at least Roman times up to the present day. Geology The Purbeck Group is a sequence of sedimentary rocks that were deposited in a shallow freshwater to brackish lagoonal setting. It ranges in age from Tithonian to Berriasian. Limestone beds are developed at various levels throughout the sequence, each with a different character, which led to them being quarried for specific uses. Towards the top of the Lulworth Formation is the 'New Vein'. In the lower part of the Durlston Formation are the 'Downs vein, 'Freestone Vein' and the 'Laning Vein'. Towards the top of the Durlston are the 'Burr' (or Broken Shell Limestone) with up to three beds of the 'Purbeck Marble' above that. Occurrence The Purbeck Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
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 limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berriasian
In the geological timescale, the Berriasian is an age/stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ago). The Berriasian succeeds the Tithonian (part of the Jurassic) and precedes the Valanginian. Stratigraphic definition The Berriasian Stage was introduced in scientific literature by Henri Coquand in 1869. It is named after the village of Berrias in the Ardèche department of France. The largely non-marine English Purbeck Formation is in part of Berriasian age.In fact, the first rocks to be described of this age were the beds of the English Purbeck Formation, named as the Purbeckian by Alexandre Brongniart in 1829 following description by Henry De la Beche, William Buckland, Thomas Webster and William Henry Fitton. The base of the Berriasian, which is also the base of the Cretaceous System, has traditionally been placed at the first ap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Building Stone
Building material is material used for construction. Many naturally occurring substances, such as clay, rock (geology), rocks, sand, wood, and even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic. The manufacturing of building materials is an established industry in many countries and the use of these materials is typically segmented into specific specialty trades, such as carpentry, Building insulation, insulation, plumbing, and roofing material, roofing work. They provide the make-up of :Human habitats, habitats and architecture, structures including homes. The total cost of building materials In history, there are trends in building materials from being natural to becoming more man-made and Composite material, composite; biodegradable to imperishable; indigenous (local) to being transported globally; repairable to disposable; chosen for increased levels of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ashlar
Ashlar () is finely dressed (cut, worked) stone, either an individual stone that has been worked until squared, or a structure built from such stones. Ashlar is the finest stone masonry unit, generally rectangular cuboid, mentioned by Vitruvius as opus isodomum, or less frequently trapezoidal. Precisely cut "on all faces adjacent to those of other stones", ashlar is capable of very thin joints between blocks, and the visible face of the stone may be quarry-faced or feature a variety of treatments: tooled, smoothly polished or rendered with another material for decorative effect. One such decorative treatment consists of small grooves achieved by the application of a metal comb. Generally used only on softer stone ashlar, this decoration is known as "mason's drag". Ashlar is in contrast to rubble masonry, which employs irregularly shaped stones, sometimes minimally worked or selected for similar size, or both. Ashlar is related but distinct from other stone masonry that is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purbeck Monocline
The Purbeck Monocline is a geological fold in southern England. The term 'fold' is used in geology when one or more originally flat sedimentary strata surfaces are bent or curved as a result of plastic (i.e. permanent) deformation. A monocline is a step-like fold, in which one limb is roughly horizontal. The Purbeck Monocline was formed during the late Oligocene and early Miocene epochs, about 30 million years ago. It is the northernmost 'ripple' of the Alpine Orogeny. The Purbeck Monocline gives rise to the prominent ridge of steeply dipping Cretaceous chalk which now forms the Purbeck Hills. This chalk band runs from Swyre Head via Flower's Barrow to Old Harry Rocks. From here the fold continues under the sea to The Needles and forms the central spine of the Isle of Wight. Here it is also known as the Purbeck-Isle of Wight Disturbance. The monocline continues under the English Channel as the Wight-Bray Monocline. The Purbeck Hills run east–west through the small broad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peveril Point
Peveril Point is a promontory on the east-facing coast of the Isle of Purbeck in Dorset, England, and is part of the town of Swanage. It forms the southern end of Swanage Bay. It is located at OS Grid Ref: SZ 041 787. The rocks that make up Peveril Point are shale and Portland and Purbeck limestone in a syncline structure. This has resisted erosion more than the adjacent clay of Swanage Bay; whilst the clay has eroded away over time, the limestone has remained as a promontory. On top of Peveril Point is a National Coastwatch Institution lookout. The point is also home to the Swanage lifeboat organisation. Ward, Lock and Company, ltd, & Hammond, R. J. W. (1974). ''Complete England''. London: Ward Lock, p. 94. Peveril Point contains tunnels connecting disused gun emplacements which defended the entrance to Southampton Water from the west of the Isle of Wight during World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Worbarrow Tout
Worbarrow Tout is a promontory at the eastern end of Worbarrow Bay on Isle of Purbeck in Dorset on the south coast of England, about south of Wareham and about west of Swanage. Immediately to its east is Pondfield Cove. Worbarrow Tout ("tout" means lookout) was originally part of Gad Cliff to its east, but sea erosion has virtually separated the two completely. Geology The Tout has a distinct pointed shape. It has steep angular layers of rock that visibly demonstrate the complex sedimentary folding that affected this area and that were caused by tectonic pressures as the African and European continents collided some 30 million years ago. The cliff sediments were then twisted horizontally and this is why the Chalks that are between 85 and 145 million years old are found at the rear of the bay. The sediments that face the sea at the front of the bay and form the peninsula Worbarrow Tout are the 150-million-year-old Portland limestones and 147-million-year-old Purbeck Beds. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tithonian
In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the Kimmeridgian and followed by the Berriasian (part of the Cretaceous).See for a detailed version of the geologic timescale Gradstein ''et al.'' (2004) Stratigraphic definitions The Tithonian was introduced in scientific literature by German stratigrapher Albert Oppel in 1865. The name Tithonian is unusual in geological stage names because it is derived from Greek mythology. Tithonus was the son of Laomedon of Troy and fell in love with Eos, the Greek goddess of dawn. His name was chosen by Albert Oppel for this stratigraphical stage because the Tithonian finds itself hand in hand with the dawn of the Cretaceous. The base of the Tithonian stage is at the base of the ammonite biozone of '' Hybonoticeras hybonotum''. A global reference profi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. In the past, ''Malm'' was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units. Subdivisions The Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock: Paleogeography During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow. Life forms of the epoch This epoch is well known for many famous types of dinosaurs, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Rock
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roman Britain
Roman Britain was the period in classical antiquity when large parts of the island of Great Britain were under occupation by the Roman Empire. The occupation lasted from AD 43 to AD 410. During that time, the territory conquered was raised to the status of a Roman province. Julius Caesar invaded Britain in 55 and 54 BC as part of his Gallic Wars. According to Caesar, the Britons had been overrun or culturally assimilated by other Celtic tribes during the British Iron Age and had been aiding Caesar's enemies. He received tribute, installed the friendly king Mandubracius over the Trinovantes, and returned to Gaul. Planned invasions under Augustus were called off in 34, 27, and 25 BC. In 40 AD, Caligula assembled 200,000 men at the Channel on the continent, only to have them gather seashells ('' musculi'') according to Suetonius, perhaps as a symbolic gesture to proclaim Caligula's victory over the sea. Three years later, Claudius directed four legi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
