A crag (sometimes spelled cragg, or in Scotland craig) is a rocky hill or mountain, generally isolated from other high ground.
A crag (sometimes spelled cragg, or in Scotland craig) is a rocky hill or mountain, generally isolated from other high ground.
Castle Rock (Scottish Gaelic: Creag a' Chaisteil, Scottish Gaelic pronunciation: [ˈkʰʲɾʲekˈaˈxaʃtʰʲɪl]) is a volcanic plug in the middle of Edinburgh upon which Edinburgh Castle sits. The rock is estimated to have formed some 350 million years ago during the early Carboniferous period. It is the remains of a volcanic pipe which cut through the surrounding sedimentary rock, before cooling to form very hard dolerite, a coarser-grained equivalent of basalt. Subsequent glacial erosion was resisted more by the dolerite, which protected the softer rock to the east, leaving a crag and tail formation.
The summit of the castle rock is 130 m (430 ft) above sea level, with rocky cliffs to the south, west and north, rearing up to 80 m (260 ft) from the surrounding landscape. This means that the only readily accessible route to the castle lies to the east, where the ridge slopes more gently. The defensive advantage of such a site is clear, but the geology of the rock also presents difficulties, since basalt is an extremely poor aquifer. Providing water to the Upper Ward of the castle was problematic, and despite the sinking of a 28 m (92 ft) deep well, the water supply often ran out during drought or siege, for example during the Lang Siege of 1573.
A volcanic plug, also called a volcanic neck or lava neck, is a volcanic object created when magma hardens within a vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption. In a plinian eruption the plug is destroyed and ash is ejected.
Glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail. If a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive upstanding landform.
The Clwydian Range and Dee Valley (Welsh: Bryniau Clwyd a Dyffryn Dyfrdwy) is a designated Area of Outstanding Natural Beauty (AONB; also known as a National Landscape) located in north-east Wales, covering the Clwydian Range (Welsh: Bryniau Clwyd), and the valley of the River Dee (Welsh: Afon Dyfrdwy).
Designated in 1985 as the Clwydian Range AONB, and expanded to its current extent in 2011, the Area of Outstanding Natural Beauty includes: medieval field systems, open heather moorland, prehistoric hillforts, limestone crags, broad leaved woodland, wooded valleys, and farmland.