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.

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.

[14] 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.

One large volcanic system, which was centred around what is now Snowdon, emitted an estimated 60 cubic kilometres (14 cu mi) of debris.

Some of the volcanic ash fell in the sea and formed great banks, where unstable masses sometimes slid into deeper water, creating submarine avalanches.

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.

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.

[14] During the Permian, Triassic and Jurassic (300 to 150 Mya), further episodes of desertification, subsidence and uplift occurred and Wales was alternately inundated by the sea and raised above it.

[14] 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.

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.

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.

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.

Occasionally, the coastal area of North Wales experiences some of the warmest winter conditions in the United Kingdom, with temperatures up to 18 °C (64 °F); these result from a Foehn wind, a south-westerly airflow warming up as it descends from the mountains of Snowdonia.

[17] 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 highest wind speed ever recorded in Wales at a lowland site was gusts of 108 knots (200 km/h; 124 mph) at Rhoose, in the Vale of Glamorgan, on 28 October 1989.

The boundary line very roughly follows Offa's Dyke from south to north as far as a point about 40 miles (64 km) from the northern coast, but then swings further east.

[31] In the Office for National Statistics Area Classification, local authorities are clustered into groups based in the six main census dimensions (demographic, household composition, housing, socio-economic, employment and industry sector).

[34] The division reflects, broadly, the areas where Plaid Cymru, Labour, and the Conservatives and Liberal Democrats respectively enjoyed the most political support.

[citation needed] Topography has traditionally limited the integration between North and South Wales, with the two halves virtually functioning as separate economic and social units in the preindustrial era, with successive British Government transport policy doing little to rectify it.

[citation needed] The more urbanised south, containing cities such as Cardiff, Newport and Swansea, was historically home to the coal and steel industries.

This was followed by the unitary authorities of Swansea (239,000), Rhondda Cynon Taf (234,400), Carmarthenshire (183,800), Caerphilly (178,800), Flintshire (152,500), Newport (145,700), Neath Port Talbot (139,800), Bridgend (139,200) and Wrexham (134,800).

Another feature of the settlement pattern in Wales is the share of the population living in the sparsest rural areas: 15% compared with only 1.5% in England.

Branch lines serve the South Wales Valleys, Barry, and destinations beyond Swansea which include the ferry terminals at Fishguard and Pembroke Dock.

[48] The North Wales Coast Line links Crewe and Chester to Bangor and Holyhead, from where there is a ferry service to Ireland.

[54][55] The Pembrokeshire Coast National Park was established the following year to protect the spectacular coastal scenery of West Wales.

It includes Caldey Island, the Daugleddau estuary and the Preseli Hills, as well as the entire length of the Pembrokeshire Coast Path.

The authorities have a duty to conserve the natural beauty of the area, and to promote opportunities for members of the public to enjoy and appreciate the park's special qualities.

These differ from National Parks in that the local authorities have a duty to conserve and enhance the natural beauty of the landscape but do not have an obligation to promote the enjoyment of the public.

The 19th-century English author George Borrow remarked of the waterfall, "I never saw water falling so gracefully, so much like thin, beautiful threads, as here.