32-650: Cwmystwyth mines are located in Cwmystwyth , Ceredigion , Wales and exploited a part of the Central Wales Orefield . Cwm Ystwyth is a scheduled monument , with mining activity dating back to the Bronze Age . Silver , lead , and zinc mining peaked in the 18th century, and water was extensively used in the extraction process. The Banc Ty'nddôl , the earliest gold artifact discovered in Wales,
64-645: A transverse Mercator projection with an origin (the "true" origin) at 49° N , 2° W (an offshore point in the English Channel which lies between the island of Jersey and the French port of St. Malo ). Over the Airy ellipsoid a straight line grid, the National Grid, is placed with a new false origin to eliminate negative numbers, creating a 700 km by 1300 km grid. This false origin
96-504: A grid index where the tens denote the progress from West to East and the units from South to North. In the north of Scotland, the numbering is modified: the 100 km square to the north of 39 is numbered N30; the square to the north of 49 is N40, etc. The grid is based on the OSGB36 datum (Ordnance Survey Great Britain 1936, based on the Airy 1830 ellipsoid ), and was introduced after
128-467: Is an abbreviated alphanumeric reference where the letters are simply omitted, e.g. 166712 for the summit of Ben Nevis. Unlike the numeric references described above, this abbreviated grid reference is incomplete; it gives the location relative to an OS 100×100 km square, but does not specify which square. It is often used informally when the context identifies the OS 2-letter square. For example, within
160-621: Is called the Helmert datum transformation , which results in a typical 7 m error from true. The definitive transformation from ETRS89 that is published by the Ordnance Survey is called the National Grid Transformation OSTN15. This models the detailed distortions in the 1936–1962 retriangulation, and achieves backwards compatibility in grid coordinates to sub-metre accuracy. The difference between
192-481: Is located south-west of the Isles of Scilly. In order to minimize the overall scale error, a factor of 2499/2500 is applied. This creates two lines of longitude about 180 km east and west of the central meridian along which the local scale factor equals 1, i.e. map scale is correct. Inside these lines the local scale factor is less than 1, with a minimum of 0.04% too small at the central meridian. Outside these lines
224-650: Is now the preferred coordinate reference system across Ireland. ITM is based on the Universal Transverse Mercator coordinate system (UTM), used to provide grid references for worldwide locations, and this is the system commonly used for the Channel Islands . European-wide agencies also use UTM when mapping locations, or may use the Military Grid Reference System (MGRS), or variants of it. The first letter of
256-580: The British Isles : this article describes the system created solely for Great Britain and its outlying islands (including the Isle of Man ). The Irish grid reference system is a similar system created by the Ordnance Survey of Ireland and the Ordnance Survey of Northern Ireland for the island of Ireland. The Irish Transverse Mercator (ITM) coordinate reference system was adopted in 2001 and
288-805: The Community Archives Wales project in 2007. Cwmystwyth experiences an oceanic climate ( Köppen climate classification Cfb ) similar to almost all of Wales and the United Kingdom. This translates to a narrow range of temperatures, rainfall in all seasons and low sunshine levels, particularly at upland locations such as inland Wales. The MetOffice maintains a weather station in the village, with online climate records dating back to 1959. Temperatures range from an absolute high of 32.3 °C (90.1 °F) recorded during July 2006, down to an absolute low of −16.7 °C (1.9 °F), recorded during January 1963. During an 'average' year,
320-556: The River Ystwyth " ) is a village in Ceredigion , Wales near Devil's Bridge , and Pont-rhyd-y-groes . The Ordnance Survey calculates Cwmystwyth to be the centre point of Wales ( 52°19′48.791″N 3°45′59.072″W / 52.33021972°N 3.76640889°W / 52.33021972; -3.76640889 ( Centre of Wales ) ; grid reference SN7972871704 ). Discovery of small, oval-shaped stone tools in
352-755: The retriangulation of 1936–1962 . It replaced the Cassini Grid which had previously been the standard projection for Ordnance Survey maps. The Airy ellipsoid is a regional best fit for Britain; more modern mapping tends to use the GRS80 ellipsoid used by the Global Positioning System (the Airy ellipsoid assumes the Earth to be about 1 km smaller in diameter than the GRS80 ellipsoid, and to be slightly less flattened). The British maps adopt
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#1732775411828384-577: The British National Grid is derived from a larger set of 25 squares of size 500 km by 500 km, labelled A to Z, omitting one letter (I) (refer diagram below), previously used as a military grid. Four of these largest squares contain significant land area within Great Britain: S, T, N and H. The O square contains a tiny area of North Yorkshire , Beast Cliff at OV 0000 , almost all of which lies below mean high tide. For
416-588: The OSGB 36 lines in South Cornwall , the difference diminishing to zero in the Scottish Borders , and then increasing to about 50 m north on the north coast of Scotland . (If the lines are further east , then the longitude value of any given point is further west . Similarly, if the lines are further south, the values will give the point a more northerly latitude.) The smallest datum shift
448-709: The OSGB36 National Grid location for Ben Nevis is at 216600, 771200. Grid references may also be quoted as a pair of numbers: eastings then northings in metres, measured from the southwest corner of the SV square. 13 digits may be required for locations in Orkney and further north. For example, the grid reference for Sullom Voe Oil Terminal in the Shetland islands may be given as HU396753 or 439668,1175316 . Another, distinct, form of all-numeric grid reference
480-434: The archive includes transcriptions of census data, baptismal registers and log books as a means of interpreting the history of the village. In the long-term, it is hoped that the project will act as a springboard for establishment of a Cwmystwyth History Society which would produce materials relating to the area and eventually to the creation of a heritage centre to showcase the history of the village. Cofnodion Cwmystwyth joined
512-447: The area points to the fact that it has been mined for lead since the time of ancient Britons and during Roman occupation. Documentation of mining activities occurred during the reign of Elizabeth I . She engaged the services of two German miners, then went on to sub-let to Hugh Myddleton. The only significant flat area of the cwm is found before the river reaches maturity near Trawsgoed some 6 miles (9.7 km) further west. Above
544-433: The context of a location known to be on OS Landranger sheet 41 (which extends from NN000500 in the south-west to NN400900 in the north-east) the abbreviated grid reference 166712 is equivalent to NN166712. If working with more than one Landranger sheet, this may also be given as 41/166712. Alternatively, sometimes numbers instead of the two-letter combinations are used for the 100×100 km squares. The numbering follows
576-570: The coordinates on different datums varies from place to place. The longitude and latitude positions on OSGB 36 are the same as for WGS 84 at a point in the Atlantic Ocean well to the west of Great Britain. In Cornwall , the WGS 84 longitude lines are about 70 metres east of their OSGB 36 equivalents, this value rising gradually to about 120 m east on the east coast of East Anglia . The WGS 84 latitude lines are about 70 m south of
608-466: The digits is for the first coordinate and the second half for the other. The most common usage is the six figure grid reference , employing three digits in each coordinate to determine a 100 m square. For example, the grid reference of the 100 m square containing the summit of Ben Nevis is NN 166 712 . (Grid references may be written with or without spaces; e.g., also NN166712.) NN has an easting of 200 km and northing of 700 km, so
640-642: The lead concentration decreasing to below 0.1 mg/L. The number of species increased to 63 by 1939, but there were still no fish present in the river. The lead concentration fell to below 0.05 mg/L. Fish had returned to most of the river by 1975. However, there were no fish within a 3 km stretch below the Cwm Ystwyth mine. 52°21′19″N 3°46′09″W / 52.355299°N 3.769283°W / 52.355299; -3.769283 Cwmystwyth Cwmystwyth (also Cwm Ystwyth , Welsh pronunciation: [kʊmˈəstʊɨθ] ; English: "valley of
672-473: The local scale factor is greater than 1, and is about 0.04% too large near the east and west coasts. Grid north and true north are only aligned on the central meridian (400 km easting) of the grid which is 2° W (OSGB36) and approx. 2° 0′ 5″ W ( WGS 84 ). A geodetic transformation between OSGB 36 and other terrestrial reference systems (like ITRF2000 , ETRS89 , or WGS 84 ) can become quite tedious if attempted manually. The most common transformation
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#1732775411828704-455: The ore. In the case of Cwm Ystwyth mine, much of the water was brought in by contour hugging leats from several miles upstream. The channel of the leat can still be followed on the hillside and is clearly visible from the road on the opposite side of the valley. Much of the water was used for hushing , prospecting and working the ore in the open. In October 2002, the Banc Ty'nddôl sun-disc
736-440: The second letter, each 500 km square is subdivided into 25 squares of size 100 km by 100 km, each with a letter code from A to Z (again omitting I) starting with A in the north-west corner to Z in the south-east corner. These squares are outlined in light grey on the "100km squares" map, with those containing land lettered. The central (2° W) meridian is shown in red. Within each square, eastings and northings from
768-572: The site is evidence for all phases of mining activity; from the Bronze Age, through the medieval period , to its revival in the 18th century and the peak of activity, with a subsequent decline in the late 19th and the early 20th century. It has been designated as a Scheduled Ancient Monument . The site also features prominently in the Upland Ceredigion Landscape of Historic Interest. Silver, lead and zinc have been mined in
800-412: The south west corner of the square are given numerically. For example, NH0325 means a 1 km square whose south-west corner is 3 km east and 25 km north from the south-west corner of square NH. A location can be indicated to varying resolutions numerically, usually from two digits in each coordinate (for a 1 km square) through to five (for a 1 m square); in each case the first half of
832-611: The valley of the River Ystwyth since Roman times , an activity that reached its peak in the 18th century. The largest of the very many mines was Cwmystwyth Mine. It is reputed that the average age at death of the miners in Cwmystwyth was 32, largely because of acute lead poisoning . There is no longer any active metal mining in the Ystwyth valley. Water was extensively used during the silver and lead mining process to extract
864-600: The village to the east steep slopes rise to the Elenydd moors, above the cwm of the Nant Milwyn, at the head of the hill of Domen Milwyn. Cofnodion Cwmystwyth is a recently established local history group based in Cwmystwyth. The group has 14 regular members of various ages drawn from the Communities First area of Tregaron Uplands, all with a passion for the history of the area. As well as including images,
896-461: The warmest day will likely reach 26.1 °C (79.0 °F) and the coldest night fall to −8.0 °C (17.6 °F). In total just over 3 days should record a temperature of 25.1 °C (77.2 °F) or above, and 59.3 nights should report an air frost. Rainfall, as one might expect for an elevated place in Wales, is high, at nearly 2,000 millimetres (79 in) a year. At least 1 millimetre (0.039 in) will be observed on over 189 days of
928-539: The west of the Isles of Scilly . The Ordnance Survey (OS) devised the national grid reference system, and it is heavily used in its survey data, and in maps based on those surveys, whether published by the Ordnance Survey or by commercial map producers. Grid references are also commonly quoted in other publications and data sources, such as guide books and government planning documents. A number of different systems exist that can provide grid references for locations within
960-486: The year, on average. All averages refer to the period 1971–2000. Ordnance Survey National Grid The Ordnance Survey National Grid reference system ( OSGB ), also known as British National Grid ( BNG ), is a system of geographic grid references , distinct from latitude and longitude , whereby any location in Great Britain can be described in terms of its distance from the origin (0, 0), which lies to
992-439: Was discovered on the mining site. The disc is over 4,000 years old, which makes it the earliest gold artifact discovered in Wales. A survey of the River Ystwyth in 1919 showed that due to mining activity in the area, the fauna was restricted to nine species, mostly of insects. The lead concentration in the river was found to be 0.4 mg/L. In 1922, another survey was conducted; the number of species had increased to 26, with
Cwmystwyth Mines - Misplaced Pages Continue
1024-417: Was found on the site in 2002. Mining in the area caused substantial environmental impact; lead concentrations in the River Ystwyth declined from 0.4 mg/L in 1919 to below 0.05 mg/L in 1939, with fish populations returning to most of the river by 1975. Cwm Ystwyth is considered the most important non-ferrous metal mining site in Wales , providing a premier example of mining heritage in Ceredigion . Within
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