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It is a "convenience" label rather than a geological term, since at least 46 different rock types are represented. One of the most common rocks in the assemblage is known as Preseli Spotted Dolerite—a chemically altered igneous rock containing spots or clusters of secondary minerals replacing plagioclase feldspar. It is a medium grained dark ...
Carn Menyn sits on top of the Preseli ridge, close to the stone setting of Bedd Arthur. It consists of a series of outcrops of spotted dolerite similar to that of other tors in the area, and several other prehistoric sites have been identified nearby.
However, in 2015, researchers reported they had confirmed the Preseli Spotted Dolerite stones at Stonehenge came from two Neolithic quarries at Carn Goedog and Craig Rhos-y-felin in the Preseli Hills. Using radiocarbon dating, researchers dated the quarry activities to around 3400 BC for Craig Rhos-y-felin and 3200 BC for Carn Goedog.
Bedd Arthur ("Arthur's Grave") is a possibly Neolithic hengiform monument megalithic site in the Preseli Hills in the Welsh county of Pembrokeshire.Thirteen upright stones and at least 2 fallen ones, each around 0.6 metres (2.0 ft) high form an oval horseshoe with similarities to the earliest form of Stonehenge.
The building stones of Wales are many and varied reflecting the diverse geology of the country. Some of the earliest known use of natural stone for building purposes was the sourcing of Ordovician dolerite in the Preseli Hills for the 'bluestone' lintels of Stonehenge.
It is estimated that the quarrying, fashioning, transport and construction of such an amount represents about four work days for a single worker (assuming a 10-hour day). The original monument, Cairn 1, had a volume of about 2,000 cubic metres; it is built of 1,000 tons of granite and 3,000 tons of dolerite.
Diabase (/ ˈ d aɪ. ə ˌ b eɪ s /), also called dolerite (/ ˈ d ɒ l. ə ˌ r aɪ t /) or microgabbro, [1] is a mafic, holocrystalline, subvolcanic rock equivalent to volcanic basalt or plutonic gabbro.
Waun Mawn (Welsh for "peat moor") is a megalithic site in the Preseli Mountains of Pembrokeshire, Wales.Following excavations in 2018, it became the site of a supposed dismantled Neolithic stone circle.