SUMMARY / RELATED TOPICS

Convergent boundary

A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate slides beneath the other causing a process known as subduction; the subduction zone can be defined by a plane where many earthquakes occur, called the Benioff Zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, orogenesis, destruction of lithosphere, deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, continental-continental lithosphere; the geologic features related to convergent boundaries vary depending on crust types. Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle; these convection cells bring hot mantle material to the surface along spreading centers creating new crust. As this new crust is pushed away from the spreading center by the formation of newer crust, it cools and becomes denser.

Subduction initiates. The force of gravity helps drive the subducting slab into the mantle. Evidence supports; as the cool subducting slab sinks deeper into the mantle, it is heated causing dehydration of hydrous minerals. This releases water into the hotter asthenosphere, which leads to partial melting of asthenosphere and volcanism. Both dehydration and partial melting occurs along the 1000 °C isotherm at depths of 65 – 130 km; some lithospheric plates consist of both oceanic lithosphere. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Neither continental plate will subduct, it is that the plate may break along the boundary of continental and oceanic crust. Seismic tomography reveals pieces of lithosphere. Subduction zones are areas where one lithospheric plate slides beneath another at a convergent boundary due to lithospheric density differences; these can vary. Subduction zones are marked by an abundance of earthquakes, the result of internal deformation of the plate, convergence with the opposing plate, bending at the oceanic trench.

Earthquakes have been detected to a depth of 670 km. The cold and dense subducting plates are pulled into the mantle and help drive mantle convection. In collisions between two oceanic plates, the cooler, denser oceanic lithosphere sinks beneath the warmer, less dense oceanic lithosphere; as the slab sinks deeper into the mantle, it releases water from dehydration of hydrous minerals in the oceanic crust. This water causes partial melting. Partial melt will travel up through the asthenosphere reach the surface, form volcanic island arcs; when oceanic lithosphere and continental lithosphere collide, the dense oceanic lithosphere subducts beneath the less dense continental lithosphere. An accretionary wedge forms on the continental crust as deep-sea sediments and oceanic crust are scraped from the oceanic plate. Volcanic arcs form on continental lithosphere as the result of partial melting due to dehydration of the hydrous minerals of the subducting slab; some lithospheric plates consist of both oceanic crust.

Subduction initiates as oceanic lithosphere slides beneath continental crust. As the oceanic lithosphere subducts to greater depths, the attached continental crust is pulled closer to the subduction zone. Once the continental lithosphere reaches the subduction zone, subduction processes are altered as continental lithosphere is more buoyant and resists subduction beneath other continental lithosphere. A small portion of the continental crust may be subducted until the slab breaks, allowing the oceanic lithosphere to continue subducting, hot asthenosphere to rise and fill the void, rebound of the continental lithosphere. Evidence of this continental rebound include ultrahigh pressure metamorphic rocks which form at depths of 90 – 125 km that are exposed at the surface; the oceanic crust contains hydrated minerals such as the amphibole group. During subduction, oceanic lithosphere is heated and metamorphosed causing dehydration of these hydrous minerals contained within basalts, releasing water into the asthenosphere.

The release of water into the asthenosphere leads to partial melting. Partial melting allows the rise of more buoyant, hot material and can lead to volcanism at the surface and emplacement of plutons in the subsurface; these processes which generate magma are not understood. Where these magmas reach the surface they create volcanic arcs. Volcanic arcs can form as arcs on continental crust. Three series of volcanic rocks form arcs, calc-alkaline, alkaline which are rare. Back arc basins form behind a volcanic arc and are associated with extensional tectonics and high heat flow being home to seafloor spreading centers; these spreading centers are like mid ocean ridges, though the magma composition of back arc basins is more varied and contains a higher water content than mid ocean ridge magmas. Back arc basins are characterized by thin, hot lithosphere. Opening of back arc basins are still being studied but it is possible that movement of hot asthenosphere into lithosphere causes extension. Oceanic trenches are narrow topographic lows that mark convergent boundaries

Jamie Jervis

Jamie Francis Jervis is a former English cricketer. Jervis was a left-handed batsman, he was born in Staffordshire. Jervis made his debut for Staffordshire in the 1999 MCCA Knockout Trophy against the Leicestershire Cricket Board. Jervis played Minor counties cricket for Staffordshire from 1999 to 2001, which included 14 Minor Counties Championship matches and 5 MCCA Knockout Trophy matches. In 2001, he made his only List A appearance against the Worcestershire Cricket Board in the Cheltenham & Gloucester Trophy. In this match, he scored 19 runs before being dismissed by Jonathan Wright, his brother, Richie played Minor counties and List A cricket for Staffordshire. Jamie Jervis at ESPNcricinfo Jamie Jervis at CricketArchive

Comrie

Comrie is a village and parish in the southern Highlands of Scotland, towards the western end of the Strathearn district of Perth and Kinross, 7 miles west of Crieff. Comrie is a historic conservation village, situated in a national scenic area around the river Earn, its position on the Highland Boundary Fault accounts for it experiencing more earth tremors than anywhere else in Britain. The parish is twinned with Carleton Place, Canada. Comrie lies within the registration county of Perthshire and the Perth and Kinross local council area; the name Comrie is derived from the original Gaelic name con-ruith or comh-ruith translating as "running together", but more as "flowing together" or "the place where rivers meet". In modern Gaelic the name is more transcribed as Comraidh, Cuimridh or Cuimrigh; this is an apt toponym. The River Ruchill and The River Lednock are all tributaries of the Earn at Comrie, which itself feeds into the Tay. Due to its position astride the Highland Boundary Fault, Comrie experiences frequent earth tremors and has an old nickname of "Shaky Toun/Toon" or'Am Baile Critheanach'.

In the 1830s around 7,300 tremors were recorded and today Comrie records earth tremors more and to a higher intensity than anywhere else in the United Kingdom. Comrie became the site of one of the world's first seismometers in 1840, a functional replica is still housed in the Earthquake House in The Ross in Comrie; the position of Comrie on the Highland Boundary Fault gives the village a claim to the contested title of Gateway to the Highlands. To the north of the village, Ben Chonzie and the Grampian Mountains rise majestically, while to the south of the village broad open moorland is joined by lesser mountains and glens that provide a wide range of terrain and ecology. There is significant evidence of prehistoric habitation of the area, marked by numerous standing stones and archaeological remains that give insight into the original prehistoric and Celtic societies that lived here. In AD 79, the Roman General Agricola chose what are now the outskirts of Comrie as the site for a fort and temporary marching camp, due to the area's strategic position on the southern fringe of the Highlands.

It is one of the line of so-called "Glen blocking" forts running from Drumquhassle to Stracathro and including the legionary fortress of Inchtuthil. The temporary camp was c. 22 acre in size. An infamous battle between the Celts and Romans is known to have occurred on the unidentified mountain Mons Graupius; the area around Comrie, Strathearn, is one of several proposed battle sites. James V of Scotland came to Comrie and Cultybraggan in September to hunt deer. Records survive of the food he consumed included bread and fish sent from Sterling. Comrie's early prosperity derived from weaving; this was done as domestic piecework. Comrie was important as a droving town. Cattle destined for the markets of the Scottish Lowlands and England would be driven south from their grazing areas in the Highlands. River crossings, such as at Comrie, were important staging posts on the way south. Much of the land around Comrie was owned by the Drummond family, Earls of Perth, latterly Earls of Ancaster, whose main seat was Drummond Castle, south of Crieff.

Another branch of the Drummonds owned Drummondernoch, to the west of the town. Aberuchill Castle, just outside Comrie was a Campbell seat. Over the years the village has grown to incorporate many smaller satellite settlements, including The Ross a small settlement to the west of the village contained within a river peninsula which became more accessible when the Ross Bridge was constructed in 1792. Before that the peninsula was only reached by a river ford; the once isolated communities in the surrounding glens and mountains, such as Invergeldie in Glen Lednock and Dalchruin in Glen Artney, have come to be seen as part of Comrie village. They existed as small isolated settlements – for instance, Glen Lednock contained 21 different settlements of 350 individual structures and 25 corn-drying kilns. However, these Gaelic-speaking hamlets were eviscerated by the Highland Clearances of the 18th and 19th centuries. Comrie underwent something of a renaissance in the early 19th century and Victorian periods as an attractive location for wealthy residents and visitors, an image, maintained to this day.

This popularity helped to bring the railway in 1893, when the Caledonian Railway completed a branch line from Crieff. The line was extended to meet the Callander and Oban Railway at Lochearnhead; the Comrie–Lochearnheadline was closed in 1951 and the Comrie–Crieff line in 1964, due to the improved road network in the area. Comrie's mountainous setting with abundant streams and lochs brought a number of hydro-electric power plants into the area in the earlier 20th century. A dam was built in water piped to another plant from Loch Earn in the west. Today Comrie is an attractive retirement village, recording the largest proportion of over-65s in Scotland in the 1991 census, its economy is supplemented by wildlife tourism. As with other Highland villages, recent decades have seen an influx of relocated residents, predominantly from England and the Scottish central belt