Cardiff - Geography

Geography

The centre of Cardiff is relatively flat and is bounded by hills on the outskirts to the east, north and west. Its geographic features were influential in its development as the world's largest coal port, most notably its proximity and easy access to the coal fields of the south Wales valleys. The highest point in the authority is Garth Hill 307 metres above sea level.

Cardiff is built on reclaimed marshland on a bed of Triassic stones; this reclaimed marshland stretches from Chepstow to the Ely Estuary, which is the natural boundary of Cardiff and the Vale of Glamorgan. Triassic landscapes of this part of the world are usually shallow and low-lying which accounts and explains the flatness of the centre of Cardiff. The classic Triassic marl, sand and conglomerate rocks are used predominantly throughout Cardiff as building materials. Many of these Triassic rocks have a purple complexion, especially the coastal marl found near Penarth. One of the Triassic rocks used in Cardiff is "Radyr Stone", a freestone which as it name suggests is quarried in the Radyr district. Cardiff has also imported some materials for buildings: Devonian sandstones (the Old Red Sandstone) from the Brecon Beacons has been used. Most famously, the buildings of Cathays Park, the civic centre in the centre of the city, are built of Portland stone which was imported from Dorset. A widely used building stone in Cardiff is the yellow-grey Liassic limestone rock of the Vale of Glamorgan, including the very rare "Sutton Stone", a conglomerate of lias limestone and carboniferous limestone.

Cardiff is bordered to the west by the rural district of the Vale of Glamorgan—also known as The Garden of Cardiff— to the east by the city of Newport, to the north by the South Wales Valleys and to the south by the Severn Estuary and Bristol Channel. The River Taff winds through the centre of the city and together with the River Ely flows into the freshwater lake of Cardiff Bay. A third river, the Rhymney flows through the east of the city entering directly into the Severn Estuary.

Cardiff is situated near the Glamorgan Heritage Coast, stretching westward from Penarth and Barry—commuter towns of Cardiff—with striped yellow-blue Jurassic limestone cliffs. The Glamorgan coast is the only part of the Celtic Sea that has exposed Jurassic (blue lias) geology. This stretch of coast, which has reefs, sandbanks and serrated cliffs, was a ship graveyard; ships sailing up to Cardiff during the industrial era often never made it as far as Cardiff as many were wrecked around this hostile coastline during west/south-westerly gales. Consequently, smuggling, deliberate shipwrecking and attacks on ships were common.