Geography of Wales
is a country that is part of the United Kingdom and whose physical geography is characterised by a varied coastline and a largely upland interior. It is bordered by England to its east, the Irish Sea to its north and west, and the Bristol Channel to its south. It has a total area of and is about from north to south and at least wide. It comprises 8.35 percent of the land of the United Kingdom. It has a number of offshore islands, by far the largest of which is Anglesey. The mainland coastline, including Anglesey, is about in length. As of 2014, Wales had a population of about 3,092,000; Cardiff is the capital and largest city and is situated in the urbanised area of South East Wales.
Wales has a complex geological history which has left it a largely mountainous country. The coastal plain is narrow in the north and west of the country but wider in the south, where the Vale of Glamorgan has some of the best agricultural land. Exploitation of the South Wales Coalfield during the Industrial Revolution resulted in the development of an urban economy in the South Wales Valleys, and the expansion of the port cities of Newport, Cardiff and Swansea for the export of coal. The smaller North Wales Coalfield was also developed at this time, but elsewhere in the country, the landscape is rural and communities are small, the economy being largely dependent on agriculture and tourism. The climate is influenced by the proximity of the country to the Atlantic Ocean and the prevailing westerly winds; thus it tends to be mild, cloudy, wet and windy.
Physical geography
Wales is located on the western side of central southern Great Britain. To the north and west is the Irish Sea, and to the south is the Bristol Channel. The English counties of Cheshire, Shropshire, Herefordshire and Gloucestershire lie to the east. Much of the border with England roughly follows the line of the ancient earthwork known as Offa's Dyke. The large island of Anglesey lies off the northwest coast, separated from mainland Wales by the Menai Strait, and there are a number of smaller islands.Most of Wales is mountainous. Snowdonia in the northwest has the highest mountains, with Snowdon at being the highest peak. To the south of the main range lie the Arenig Group, Cadair Idris and the Berwyn Mountains. In the northeast of Wales, between the Clwyd Valley and the Dee Estuary, lies the Clwydian Range. The 14 peaks over, all in Snowdonia, are known collectively as the Welsh 3000s.
The Cambrian Mountains run from northeast to southwest and occupy most of the central part of the country. These are more rounded and undulating, clad in moorland and rough, tussocky grassland. In the south of the country are the Brecon Beacons in central Powys, the Black Mountains spread across parts of Powys and Monmouthshire in southeast Wales and, confusingly, Black Mountain, which lies further west on the border between Carmarthenshire and Powys.
The Welsh lowland zone consists of the north coastal plain, the island of Anglesey, part of the Llŷn Peninsula, a narrow strip of coast along Cardigan Bay, much of Pembrokeshire and southern Carmarthenshire, the Gower Peninsula and the Vale of Glamorgan. The main rivers are the River Dee, part of which forms the boundary between Wales and England, the River Clwyd and the River Conwy, which all flow northwards into Liverpool Bay and the Irish Sea. Further round the coast, the Rivers Mawddach, Dovey, Rheidol, Ystwyth and Teifi flow westwards into Cardigan Bay, and the rivers Towy, Taff, Usk and Wye flow southwards into the Bristol Channel. Parts of the River Severn form the boundary between Wales and England.
The length of the coast of mainland Wales is about, and adding to this the coasts of the Isle of Anglesey and Holy Island, the total is about. Cardigan Bay is the largest bay in the country and Llyn Tegid the largest lake at. Other large lakes include Llyn Trawsfynydd at, Lake Vyrnwy at, Llyn Brenig at, Llyn Celyn at and Llyn Alaw at. Bala Lake lies in a glacial valley blocked by a terminal moraine, but the other lakes are reservoirs created by impounding rivers, to provide drinking water, hydroelectric schemes or flood defences, and many are also used recreationally.
Geology
The geology of Wales is complex and varied. The earliest outcropping rocks are from the Precambrian era, some 700 Mya, and are found in Anglesey, the Llŷn peninsula, southwestern Pembrokeshire and in places near the English border. During the Lower Palaeozoic, as seas periodically flooded the land and retreated again, thousands of metres of sedimentary and volcanic rocks accumulated in a marine basin known as the Welsh Basin. Rocks found in a quarry near to the village Llangynog, Carmarthenshire, in 1977 contain some of the Earth's oldest fossils which date from the Ediacaran period, 564 million years ago, when Wales was part of the micro-continent Avalonia.During the early and middle Ordovician period, volcanic activity increased. One large volcanic system, which was centred around what is now Snowdon, emitted an estimated of debris. Another volcano formed Rhobell Fawr near Dolgellau. During this period, great accumulations of sand, gravel and mud were deposited further south in Wales, and these gradually consolidated. Some of the volcanic ash fell in the sea and formed great banks, where unstable masses sometimes slid into deeper water, creating submarine avalanches. This caused great turbidity in the sea, after which the particles began to settle out according to particle size. The strata thus formed are called turbidites, and these are common in central Wales, being particularly obvious in the sea cliffs around Aberystwyth.
By the beginning of the Devonian period the sea was retreating from the Welsh Basin as the land was thrust up by the collision of land masses, forming a new range of mountains, the Welsh Caledonides. The Old Red Sandstone represents debris from their erosion. Elsewhere the strata were compressed and deformed, and in places, the clay minerals recrystallised, developing a grain that allowed parallel cleavage, making it easy to split the rocks into thin flat sheets of stone known as slate. In the early part of the Carboniferous period, reinvasion of southern and northern parts of Wales by the sea resulted in depositions of limestone, and extensive swamps in South Wales gave rise to peat deposits and the eventual formation of coal measures. Erosion of nearby upland areas resulted in the formation of sandstones and mudstones in the later part of the period. Southwestern Wales, in particular, was affected by the Variscan orogeny, a period when continental collisions further south caused complex folding and fracturing of the strata.
During the Permian, Triassic and Jurassic, further episodes of desertification, subsidence and uplift occurred and Wales was alternately inundated by the sea and raised above it. By the Cretaceous, Wales was permanently above sea level and in the Pleistocene, it underwent several exceptionally cold periods, the ice ages. The mountains we see today largely assumed their present shape during the last ice age, the Devensian glaciation.
In the mid 19th century, two prominent geologists, Roderick Murchison and Adam Sedgwick, used their studies of the geology of Wales to establish certain principles of stratigraphy and palaeontology. From the Latin name for Wales, Cambria, was derived the name of the earliest geological period of the Paleozoic era, the Cambrian. After much dispute, the next two periods of the Paleozoic era, the Ordovician and Silurian, were named after pre-Roman Celtic tribes of Wales, the Ordovices and Silures.
Climate
Wales has a maritime climate, the predominant winds being southwesterlies and westerlies blowing in from the Atlantic Ocean. This means that the weather in Wales is in general mild, cloudy, wet and windy. The country's wide geographic variations cause localised differences in amounts of sunshine, rainfall and temperature. Rainfall in Wales varies widely, with the highest average annual totals in Snowdonia and the Brecon Beacons, and the lowest near the coast and in the east, close to the English border. Throughout Wales, the winter months are significantly wetter than the summer ones. Snow is comparatively rare near sea level in Wales, but much more frequent over the hills, and the uplands experience harsher conditions in winter than the more low-lying parts.The mean annual temperatures in Wales are about on the coast and in low-lying inland areas. It becomes cooler at higher altitudes, with a mean decrease in annual temperatures of approximately for each of increased altitude. Consequently, the higher parts of Snowdonia experience mean annual temperatures of. At nights, the coldest conditions occur when there is little wind and no cloud cover, especially when the ground is snow-clad; the lowest temperature recorded in Wales was in conditions of this sort at Rhayader on New Year's Day, 1940, when the temperature fell to. Occasionally, the coastal area of North Wales experiences some of the warmest winter conditions in the United Kingdom, with temperatures up to ; these result from a Foehn wind, a south-westerly airflow warming up as it descends from the mountains of Snowdonia.
Rainfall in Wales is mostly as a result of the arrival of Atlantic low pressure systems and is heaviest between October and January over the whole country. The driest months are usually April, May and June, and Wales experiences fewer summer thunderstorms than England. Rainfall varies across the country with the highest records being from the greatest elevations. Snowdonia experiences total annual rainfalls exceeding whereas coastal regions of Wales and the English border may have less than. The combination of mountainous areas and Atlantic lows can produce large quantities of rain and sometimes results in flooding. The amount of snowfall varies with altitude and enormously from year to year. In the lowlands, the number of days with lying snow may vary from zero to thirty or more, with an average of about twenty in Snowdonia.
Wales is one of the windier parts of the United Kingdom. The strongest winds are usually associated with Atlantic depressions; as one of these arrives, the winds usually start in the southwest, before veering to the west and then to the northwest as the system passes by. The southwest of Pembrokeshire experiences the most gale-force winds. The highest wind speed ever recorded in Wales at a lowland site was gusts of at Rhoose, in the Vale of Glamorgan, on 28 October 1989.