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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 ...
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. The mountain-top setting provides commanding views across the surrounding countryside and across Cardigan Bay to the Llŷn Peninsula .
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.
A subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at depths less than 2 km (1.2 mi) within the crust, and has intermediate grain size and often porphyritic texture between that of volcanic rocks, which are extrusive igneous rocks, and plutonic rocks, which form much deeper in the ground. [1]
The Prospect dolerite intrusion, or Prospect intrusion, is a Jurassic picrite or dolerite laccolith that is situated in Sydney, New South Wales, Australia. [2] Lying in the heart of Cumberland Plain, in the suburb of Pemulwuy (previously Greystanes), the intrusion is Sydney's largest body of igneous rock, rising to a height of 117 metres (384 ft) above sea level. [3]
This was two days before his lookout spotted Tasmania for the first time. This was the first prognostication of mineral wealth on the west coast of Tasmania. A. W. Humphrey, a mineralogist, collected rocks and minerals from 1804. W. H. Twelvetrees and W. F. Petterd did petrographic investigations in Cygnet, around 1899. [21]
Stone was quarried from a sill of dolerite rock, which was the result of lava rising through the strata of the surrounding limestone 'Derbyshire Dome'. Tideswell Dale is part of the designated Wye Valley Site of Special Scientific Interest (SSSI) between Buxton and Bakewell , which also covers Cunning Dale, Woo Dale, Wye Dale, Chee Dale ...
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.