Llŷn Peninsula
The Llŷn Peninsula extends 30 miles into the Irish Sea from north west Wales, south west of the Isle of Anglesey. It is part of the historic county of Caernarfonshire, historic region and local authority area of Gwynedd. Much of the eastern part of the peninsula, around Criccieth, may be regarded as part of Eifionydd rather than Llŷn, although the boundary is somewhat vague; the area of Llŷn is about 400 km2, its population is at least 20,000. The peninsula was travelled by pilgrims en route to Bardsey Island, its relative isolation has helped to conserve the Welsh language and culture, for which the locality is now famous; this perceived remoteness from urban life has lent the area an unspoilt image which has made Llŷn a popular destination for both tourists and holiday home owners. Holiday homes remain a bone of contention among locals, many of whom are priced out of the housing market by incomers. From the 1970s to the 1990s, a shadowy group known as Meibion Glyndŵr claimed responsibility for several hundred arson attacks on holiday homes using incendiary devices, some of which took place in Llŷn.
The Llyn Area of Outstanding Natural Beauty covers c. 62 square miles. The name Llŷn is sometimes spelled Lleyn, although this spelling is now less common and is considered to be an anglicisation; the name is thought to be of Irish origin, to have the same root – Laigin in Irish – as the word Leinster and which occurs in Porth Dinllaen on the north coast. Following the death of Owain Whitetooth, king of Gwynedd, Owain's son Saint Einion seems to have ruled Llŷn as a kingdom separate from his brother Cuneglas' kingdom in Rhos, he is credited with having sponsored Saint Cadfan's monastery on Bardsey Island, which became a major centre of pilgrimage during medieval times. There are numerous wells throughout the peninsula. Many have holy connotations and they were important stops for pilgrims heading to the island; the most rural parts are characterised by small houses and individual farms, resembling parts of south west Ireland. There are small compact villages, built of traditional materials; the only large-scale industrial activities were quarrying and mining, which have now ceased.
The granite quarries of northern Llŷn have left a legacy of inclines and export docks, were the reason for the growth of villages such as Llithfaen and Trefor. Copper and lead were mined around Llanengan, while 196,770 long tons of manganese were produced at Y Rhiw between 1894 and 1945; the Penrhyn Dû mines have been extensively mined since the seventeenth century around Abersoch. Shipbuilding was important at Nefyn, Aberdaron and Llanaelhaearn, although the industry collapsed after the introduction of steel ships from 1880. Nefyn was an important herring port, most coastal communities fished for crab and lobster. Farming was simple and organic, but underwent major changes after the Second World War as machines came into widespread use. Land was drained and fields expanded and reseeded. From the 1950s onwards, extensive use was made of artificial fertilizers and pesticides, leading to drastic changes in the appearance of the landscape. Tourism developed after the railway to Pwllheli was built in 1867.
The town expanded with several large houses and hotels constructed, a tramway was built linking the town to Llanbedrog. After the Second World War, Butlins established a holiday camp at Penychain, which attracted visitors from the industrial cities of North West England and the West Midlands; as car ownership increased, the tourist industry spread to the countryside and to coastal villages such as Aberdaron, Abersoch and Nefyn, where many families supplemented their income by letting out rooms and houses. Pwllheli was the administrative centre of Llŷn for over 700 years, it was a royal maerdref of the Kingdom of Gwynedd, became a free borough following the English conquest. In the 18th and 19th centuries over 400 ships were built there. Llŷn is an extensive plateau dominated by mountains; the largest of these is Yr Eifl, although Garn Boduan, Garn Fadrun and Mynydd Rhiw are distinctive. Large stretches of the northern coast consist of steep cliffs and rugged rocks with offshore islands and stacks, while there are more extensive sandy beaches on the southern coast, such as Porth Neigwl and Castellmarch Beach.
North of Abersoch a series of sand dunes have developed. The landscape is divided into a patchwork of fields, with the traditional field boundaries, stone walls and cloddiau, a prominent feature; the geology of Llŷn is complex: the majority is formed from volcanic rocks of the Ordovician period. Rocks of Cambrian origin occur south of Abersoch. Numerous granite intrusions and outcrops of rhyolite form prominent hills such as Yr Eifl, whilst gabbro is found at the west end of Porth Neigwl; the western part of the peninsula is formed from Precambrian rocks, the majority of which are considered to form a part of the Monian Complex and thus to be related to the rocks of Anglesey. Numerous faults cut the area and a major shear zone - the Llyn Shear Zone - runs northeast to southwest through the Monian rocks. In 1984 there was an earthquake beneath the peninsula, which measured 5.4 on the Richter Scale and was felt in many parts of Ireland and western Britain. The area was overrun by Irish Sea ice during the ice ages and this has left a legacy of boulder clay and of meltwater channels.
Llŷn is notable for its large number of protected sites, including a national nature reserve at Cors Ge
Bay of Islands, Newfoundland and Labrador
The Bay of Islands is an extensive inlet located on the west coast of the island of Newfoundland, in Canada. The Way Office was established on July 1, 1883; the first Waymaster was Thomas Carter. The largest island in the bay is Woods Island, it is surrounded in most directions by the Long Range Mountains and it is directly north of the Lewis Hills. It is a sub-basin of the Gulf of St. Lawrence; the bay consists of many inlets such as Goose Arm. Flowing into the Bay of Islands is the Humber River. Draining Deer Lake, the Humber is one of the major rivers on the island of Newfoundland, making the Bay of Islands an important estuary. Near the mouth of the Humber River, appropriately named "Humber Mouth", is the city of Corner Brook, as well as several neighbouring suburbs; the Humber River was used for many years to float logs down to the Bay of Islands where a large Bowater pulp and paper mill at Corner Brook turned them into paper products. Today this mill is owned by Kruger Inc and its logs are transported by truck.
Although the river is used for recreational purposes, the bay still sees active shipping to and from Corner Brook's port. Other towns along the shores of the Bay of Islands are dependent upon the fishing industry; these communities include Mt Moriah, Humber Arm South, Lark Harbour, Hughes Brook, Irishtown-Summerside, Gillams, McIvers, Cox's Cove. There are still fish plants in Humber Arm South and Curling. Curling was once an incorporated community. List of communities in Newfoundland and Labrador
Ultramafic rock
Ultramafic rocks are igneous and meta-igneous rocks with a low silica content >18% MgO, high FeO, low potassium, are composed of greater than 90% mafic minerals. The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks. Intrusive ultramafic rocks are found in large, layered ultramafic intrusions where differentiated rock types occur in layers; such cumulate rock types do not represent the chemistry of the magma from. The ultramafic intrusives include the dunites and pyroxenites. Other rare varieties include troctolite; these grade into the anorthosites. Gabbro and norite occur in the upper portions of the layered ultramafic sequences. Hornblendite and phlogopite, are found. Volcanic ultramafic rocks are rare outside of the Archaean and are restricted to the Neoproterozoic or earlier, although some boninite lavas erupted within back-arc basins verge on being ultramafic.
Subvolcanic ultramafic rocks and dykes persist longer, but are rare. There is evidence of ultramafic rocks elsewhere in the solar system. Examples include picritic basalt. Komatiites can be host to ore deposits of nickel. Ultramafic tuff is rare, it has a characteristic abundance of olivine or serpentine and a scarcity or absence of feldspar and quartz. Rare occurrences may include unusual surface deposits of maars of kimberlites in the diamond fields of southern Africa and other regions. Technically ultrapotassic rocks and melilitic rocks are considered a separate group, based on melting model criteria, but there are ultrapotassic and silica-under-saturated rocks with >18% MgO which can be considered "ultramafic". Ultrapotassic, ultramafic igneous rocks such as lamprophyre and kimberlite are known to have reached the surface of the Earth. Although no modern eruptions have been observed, analogues are preserved. Most of these rocks occur as dikes, lopoliths or laccoliths, rarely, intrusions. Most kimberlite and lamproite occurrences occur as volcanic and subvolcanic maars.
Vents of Proterozoic lamproite, Cenozoic lamproite are known, as are vents of Devonian lamprophyre. Kimberlite pipes in Canada and South Africa have incompletely preserved tephra and agglomerate facies; these are diatreme events and as such are not lava flows although tephra and ash deposits are preserved. These represent low-volume volatile melts and attain their ultramafic chemistry via a different process to typical ultramafic rocks. Metamorphism of ultramafic rocks in the presence of water and/or carbon dioxide results in two main classes of metamorphic ultramafic rock. Talc carbonation reactions occur in ultramafic rocks at lower greenschist through to granulite facies metamorphism when the rock in question is subjected to metamorphism and the metamorphic fluid has more than 10% molar proportion of CO2; when such metamorphic fluids have less than 10% molar proportion of CO2, reactions favor serpentinisation, resulting in chlorite-serpentine-amphibole type assemblages. The majority of ultramafic rocks are exposed in orogenic belts, predominate in Archaean and Proterozoic terranes.
Ultramafic magmas in the Phanerozoic are rarer, there are few recognised true ultramafic lavas in the Phanerozoic. Many surface exposures of ultramafic rocks occur in ophiolite complexes where deep mantle-derived rocks have been obducted onto continental crust along and above subduction zones. Serpentine soil is a magnesium rich, calcium and phosphorus poor soil that develops on the regolith derived from ultramafic rocks. Ultramafic rocks contain elevated amounts of chromium and nickel which may be toxic to plants; as a result, a distinctive type of vegetation develops on these soils. Examples are the ultramafic woodlands and barrens of the Appalachian mountains and piedmont, the "wet maquis" of the New Caledonia rain forests, the ultramafic forests of Mount Kinabalu and other peaks in Sabah, Malaysia. Vegetation is stunted, is sometimes home to endemic species adapted to the soils. Thick, magnesite-calcrete caprock and duricrust forms over ultramafic rocks in tropical and subtropical environments.
Particular floral assemblages associated with nickeliferous ultramafic rocks are indicative tools for mineral exploration. Weathered ultramafic rocks may form lateritic nickel ore deposits. Ultramafic lava may have been detected on Io, a moon of Jupiter, because heat-mapping of Io's surface found ultra-hot areas with temperatures in excess of 1,200 °C; the lava below these hots spots is about 200 °C hotter, based on surface-to-subsurface temperature differences observed for lava on Earth. A temperature of 1,400 °C is thought to indicate the presence of ultramafic lava. Mercury appears to have ultramafic volcanic rock. Ultramafic rock types: Peridotite, norite, komatiite. Cumulate rocks and rock types: chromitite, anorthosite Ultramafic-associated ore deposits: Lateritic nickel ore deposits, kambalda type komatiitic nickel ore deposits, diamond Kimberlite, lamprophyre Ophiolite Ultramafic to mafic layered intrusions Igneous differentiation, fractiona
Sediment gravity flow
A sediment gravity flow is one of several types of sediment transport mechanisms, of which most geologists recognize four principal processes. These flows are differentiated by their dominant sediment support mechanisms, which can be difficult to distinguish as flows can be in transition from one type to the next as they evolve downslope. Sediment gravity flows are represented by four different mechanisms of keeping grains within the flow in suspension. Grain flow – Grains in the flow are kept in suspension by grain-to-grain interactions, with the fluid acting only as a lubricant; as such, the grain-to-grain collisions generate a dispersive pressure that helps prevent grains from settling out of suspension. Although common in terrestrial environments on the slip faces of sand dunes, pure grain flows are rare in subaqueous settings. However, grain-to-grain interactions in high-density turbidity currents are important as a contributing mechanism of sediment support. Liquefied/fluidized flow – Form in cohesionless granular substances.
As grains at the base of a suspension settle out, fluid, displaced upward by the settling generates pore fluid pressures that may help suspend grains in the upper part of the flow. Application of an external pressure to the suspension will initiate flow; this external pressure can be applied by a seismic shock, which may transform loose sand into a viscous suspension as in quicksand. As soon as the flow begins to move, fluid turbulence results and the flow evolves into a turbidity current. Flows and suspensions are said to be liquefied when the grains settle downward through the fluid and displace the fluid upwards. By contrast and suspensions are said to fluidized when the fluid moves upward through the grains, thereby temporarily suspending them. Most flows are liquefied, many references to fluidized sediment gravity flows are in fact incorrect and refer to liquefied flows. Debris flow or mudflow – Grains are supported by the strength and buoyancy of the matrix. Mudflows and debris flows have cohesive strength, which makes their behavior difficult to predict using the laws of physics.
As such, these flows exhibit non-newtonian behavior. Because mudflows and debris flows have cohesive strength, unusually large clasts may be able to float on top of the mud matrix within the flow. Turbidity current – Grains are suspended by fluid turbulence within the flow; because the behavior of turbidity currents is predictable, they exhibit newtonian behavior, in contrast to flows with cohesive strength. The behavior of turbidity currents in subaqueous settings is influenced by the concentration of the flow, as packed grains in high-concentration flows are more to undergo grain-to-grain collisions and generate dispersive pressures as a contributing sediment support mechanism, thereby keep additional grains in suspension. Thus, it is useful to distinguish between low-density and high-density turbidity currents. A powder snow avalanche is a turbidity current in which air is the supporting fluid and suspends snow granules in place of sand grains. Although the deposits of all four types of sediment support mechanisms are found in nature, pure grain flows are restricted to aeolian settings, whereas subaqueous environments are characterized by a spectrum of flow types with debris flows and mud flows on one end of the spectrum, high-density and low-density turbidity currents on the other end.
It is useful in subaqueous environments to recognize transitional flows that are in between turbidity currents and mud flows. The deposits of these transitional flows are referred to by a variety of names, some of the more popular being "hybrid-event beds", linked debrites" and "slurry beds". Powder snow avalanches and glowing avalanches are examples of turbidity currents in non-marine settings. Grain flow deposits are characterized by a coarsening-upward distribution of grain sizes within the bed; this results from smaller grains within the flow falling down in between larger grains during grain-to-grain collisions, thereby depositing preferentially at the base of flow. Although present as grain avalanches in terrestrial sand dunes, grain flows are rare in other settings. However, inverse graded beds resulting from grain flow processes do make up so-called "traction carpets" in the lower intervals of some high-density turbidites. Liquefied flow deposits are characterized by de-watering features, such as dish structures, that result from upward escaping fluid within the flow.
As with pure grain flows, pure liquefied flows occur on their own. However, liquefied flow processes are important as grains within turbidity currents begin to settle out and displace fluid upwards; this dish structures and related features, such de-watering pipes, are found in turbidites. Debris flow deposits are characterized by a bimodal distribution of grain sizes, in which larger grains and/or clasts float within a matrix of fine-grained clay; because the muddy matrix has cohesive strength, unusually large clasts may be able to float on top of the muddy material making up the flow matrix, thereby end up preserved on the upper bed boundary of the resulting deposit. Low-density turbidity current deposits are characterized by a succession of sedimentary structures referred to as the Bouma sequence, which result from decreasing energy within the flow, as the turbidity current moves downslope. High-density turbidity current deposits are characterized by much coarser grain size than in low-density turbidites, with the basal portions of the deposits characterized by features that result from the close proximity of the grains to
Melee
Melee or pell-mell battle refers to disorganized close combat in battles fought at abnormally close range with little central control once it starts. In the 1579 translation of Plutarch's Lives of the noble Grecians and Romanes, Sir Thomas North uses the term'pelmel' to refer to a disorganized retreat; the phrase was used in its current spelling in Shakespeare's Richard III, 1594: "March on, ioine brauelie, let vs to it pell mell, If not to heauen hand in hand to hell." The phrase comes from the French expression pêle-mêle, a rhyme based on the old French mesler, meaning to mix or mingle. The French term melee was first used in English in c. 1640. In military aviation, a melee has been described as "n air battle in which several aircraft, both friend and foe, are confusingly intermingled". Lord Nelson described his tactics for the Battle of Trafalgar as inducing a "pell mell battle" focused on engagements between individual ships where the superior morale and skill of the Royal Navy would prevail.
The destroyer night action of the second Naval Battle of Guadalcanal on 13 November 1942, was so utterly chaotic and the ships were so intermingled that an officer on USS Monssen likened it to "a barroom brawl after the lights had been shot out". Close quarters combat Melee Combat Melee weapon Galley tactics Chance medley Super Smash Bros. Melee Fremont-Barnes, Trafalgar 1805: Nelson's Crowning Victory, Osprey Publishing, p. 38 38, ISBN 978-1-84176-892-2 Kumar, Bharat.
Arabian-Nubian Shield
The Arabian-Nubian Shield is an exposure of Precambrian crystalline rocks on the flanks of the Red Sea. The crystalline rocks are Neoproterozoic in age. Geographically - and from north to south - the ANS includes parts of Israel, Jordan, Saudi Arabia, Eritrea, Ethiopia and Somalia; the ANS in the north is exposed as part of the Sahara Desert and Arabian Desert, in the south in the Ethiopian Highlands, Asir province of Arabia and Yemen Highlands. The ANS was the site of some of man's earliest geologic efforts, principally by the ancient Egyptians to extract gold from the rocks of Egypt and NE Sudan; this was the most worked of all metals and does not tarnish. All of the gold deposits in Egypt and northern Sudan were exploited by Egyptians; the earliest preserved geologic map was made in 1150 BCE to show the location of gold deposits in Eastern Egypt. New gold discoveries have been found in Sudan and Saudi Arabia. Pharonic Egyptians quarried granite near Aswan and floated this down the Nile to be used as facing for the pyramids.
The Greek name for Aswan, Syene. The Romans followed this tradition and had many quarries in the northern part of the Eastern Desert of Egypt where porphyry and granite were mined and shaped for shipment. Precious and industrial metals, including gold, copper, zinc and lead, have been mined in Saudi Arabia for at least 5,000 years; the most productive mine in Saudi Arabia, Mahd adh Dhahab, has been periodically exploited for its mineral wealth for hundreds or thousands of years and is reputed to be the original source of King Solomon's legendary gold. Today, mining at Mahd adh Dhahab is conducted by Ma'aden. Deposits of iron, mineral sands and phosphates have been found in many locations. Mining in the Eastern Desert of Egypt and Sudan is limited due to shortage of water and infrastructure. One option would be to bring water from the Nile by pipeline; the Arabian-Nubian Shield is the northern half of a great collision zone called the East African Orogeny. This collision zone formed near the end of Neoproterozoic time when East and West Gondwana collided to form the supercontinent Gondwana.
The East African orogeny extends southward to the Mozambique Belt, is a subset of the overall Pan-African orogeny. The assembly of Gondwana coincided with the breakup of Rodinia, closure of the Mozambique Ocean, growth of the shield at 870 Ma This shield growth extended for the next 300 Ma. and included island arc convergence and terrane suturing at 780 Ma, with final assembly by 550 Ma. At this time, the East African Orogen became a passive margin and the southern shore of the Paleo-Tethys Ocean; the shield is divided into crustal blocks or tectonostratigraphic terranes delineated by ophiolite shear zones or sutures. These terranes are paired across the Red Sea, starting from the south, these include Nakfa with Asir, Haya with Jiddah and Gebeit with Hijaz, Eastern Desert with Midyan. In addition the Halfa and Bayuda terranes are in the western portion of the shield, the Hulayfah, Ha'il, Afif, Ad Dawadimi, Ar Rayn terranes in the eastern portion. Key amalgamation events, starting 780-760 Ma, with the formation of the Tabalah-Tarj Shear Zone, the gneiss Afaf Belt, the 600 km long and 565 km wide Bi'r Umq and Nakasib Suture, an ophiolite-decorated fold-shear zone, between the Jiddah-Haya and Hijaz-Gebeit Terranes.
Between 750-660 Ma, the Atmur-Delgo Suture formed as Halfa Terrane ophiolite nappes were thrust onto the Bayuda Terrane. The Allaqi-Heiani-Sol and Hamed-Onib-Yanbu Suture formed, consisting of nappes and portions of ophiolite along an east-trending shear zone between the Gebeit-Hijaz and Eastern Desert Terrane and Midyan Terranes. Between 680-640 Ma, the 600 km long and 5-30 km wide Hulayfah-Ad Dafinah-Ruwah Suture formed between the Afif Terrance and terranes to the southwest; the Halaban Suture formed between the Afif and Ad Dawadimi Terranes as a nappe of Halaban ophiolite thrust westward. In addition, the Ar Amar Suture, consisting of the Al Amar Fault zone with ophiolite lenses, between the Ad Dawadimi and Ar Rayan Terranes, while the Nabitah Fault Zone formed in Asir Terrane; the final amalgamaton event occurred 650-600 Ma, when the Keraf Suture, consisting of ophiolite folded and sheared rocks, formed between the Bayuda-Halfa and Gebeit-Gabgaba Terranes. Post-amalgamation events include the formation of the Huqf Supergroup in Oman and W. Saudi Arabia, which accumulated in basement basins, the first 1100 m of which include glaciomarine deposits with diamictites and dropstones from the Sturtian and Marinoan glaciations.
Gneiss belts and domes forming in the Late Neoproterozoic include the Kirsh gneiss in the Arabian shield and the Meatiq gneiss dome in the Eastern Desert. Late Neoproterozoic shear zones include the Hamisana Shear Zone, the Ar Rika- Qazaz Shear Zone within the Najd Fault System, the Oko Shear Zone. A number of features have been ascribed to late stage extensional tectonics including a widespread NE-SW trending dyke swarm, NE-SW trending normal faults and NW-SE trending sedimentary basins filled with post-orogenic molasse depositsCrustal weaknesses before 500 Ma influenced continental rifting, as the Arabian peninsula moved away from Africa, the formation of the Red Sea Basin at the start of
Narooma Terrane
The Narooma Accretionary Complex or Narooma Terrane is a geological structural region on the south coast of New South Wales, Australia, the remains of a subduction zone or an oceanic terrane. It can be found on the surface around Narooma, Batemans Bay and down south into Victoria near Mallacoota, it has attached itself to the Lachlan Fold Belt and has been considered as either an exotic terrane or as a part of the fold belt. Rocks are turbidites, block in matrix mélange and volcanics; the accretionary complex itself could either be the toe of a subduction zone, or an accretionary prism. It was moved by the Pacific Plate westwards for about 2500 km until it encountered the east coast of Gondwana, it is part of the Mallacoota Zone according to Willman, which in turn is part of the Eastern Lachlan Fold Belt, part of the Benambra Terrane. The complex is made up of an imbricate stack in a sequence, the same both at Narooma and Murruna Point, Batemans Bay; the top layer consists of turbidite sequence from the Early Ordovician.
Below this is a high strain zone full of broken fragments. Special textures from the high strain zone include pressure solution, dilational veins and boudinage; some of the rock appears as mylonite. Underneath the high strain is chert from the Late Cambrian to Late Ordovician; the lowest part of the stack is block in mélange. The blocks are turbidite, but includes chert, some pillow lava basalt; the blocks are at different sizes all mixed together. The sediments were deformed into these blocks. Deformation has developed a cleavage with lenses of chlorite and white mica; the strike direction of the cleavage is 330°. The interpretation of the mélange is that it is either an upwelling; the mélange was underplated beneath the chert layer. Pockets of underplated material are expected to form low angle detachments; the inland zone has a chevron folded structure with reverse faults. From the stratigraphic point of view the terrane comprises the Wagonga Group; this consists of the Narooma Chert overlain by the Bogolo Formation.
Deep sea chert was deposited on the Pacific ocean floor over a period of 50 million years from Late Cambrian to Ordovician. Fossils from the chert include the conodonts Paracordylodus Acodus cf. A. comptus. The terrane approached the continental margin and began to include sediments derived from the continent, such as sandstone, siltstone and shale as well as chert bands. After formation the terrane was accreted to the Lachlan Fold Belt in the early Silurian; the rock was deformed in the Benambran Orogeny in early Silurian. A low angle oblique imbrication formed. Rocks have become more deformed closer to the coast; the country here was shortened between middle Silurian to Middle Devonian in the east–west direction, with many folds and thrust faults. Inland the rocks have developed a scaly cleavage; the chert on the coast has developed a dextral shear
