About
178
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Introduction
Current institution
Additional affiliations
February 2019 - present
February 2019 - February 2024
May 2018 - January 2020
Education
September 1974 - July 1979
September 1971 - July 1974
University College Wales, Aberystwyth
Field of study
- Geology
Publications
Publications (178)
Understanding the provenance of megaliths used in the Neolithic stone circle at Stonehenge, southern England, gives insight into the culture and connectivity of prehistoric Britain. The source of the Altar Stone, the central recumbent sandstone megalith, has remained unknown, with recent work discounting an Anglo-Welsh Basin origin1,2. Here we pres...
Maceheads are distinctive perforated stone objects that occur in Neolithic and Bronze Age sites across Europe. Maceheads of different forms have been found across Britain, but with a marked concentration in Scotland and especially in Orkney. Widely regarded as ceremonial objects, they have been invariably interpreted as weapons, or symbols of power...
In-field compositional analysis of large prehistoric relics, such as the Altar Stone at Stonehenge (England), is limited due to the size of the relics and difficulty in obtaining samples that can be analyzed in a laboratory. In this study, a portable Raman spectroscopy system was used to analyze the Altar Stone to help determine its origin and clas...
The Llangynog Inlier of south Wales contains an assemblage of Ediacaran macrofossils from a shallow-marine environment, including discoidal morphs of Aspidella and rare examples of Hiemalora , Palaeopascichnus and Yelovichnus . These are taxa found at other sites in the Avalonian microcontinent (e.g. Charnwood Forest and eastern Newfoundland) and i...
A rhyolite boulder collected by R. S. Newall in 1924 from an excavation at Stonehenge has been pivotal to arguments concerning glacial versus human transport of the bluestones to Stonehenge. Initial studies suggested that the boulder came from north Wales, and hence was a probable glacial erratic. New petrographic and geochemical analyses however s...
Excavations at two of the sources of Stonehenge’s bluestones in Mynydd Preseli, west Wales, have led to the discovery of stone tools associated with megalith quarrying in the final centuries of the fourth millennium BC, shortly before the suspected date of the bluestones’ erection at Stonehenge, 240 km away. Among the most plentiful of these tools...
In response to Timothy Darvill's article, ‘Mythical rings?’ (this issue), which argues for an alternative interpretation of Waun Mawn circle and its relationship with Stonehenge, Parker Pearson and colleagues report new evidence from the Welsh site and elaborate on aspects of their original argument. The discovery of a hearth at the centre of the c...
A Neolithic stone circle at Waun Mawn, in the Mynydd Preseli, west Wales, has been proposed as the original location of some dolerite megaliths at Stonehenge, including one known as Stone 62. To investigate this hypothesis, in-situ analyses, using a portable XRF, have been obtained for four extant non-spotted doleritic monoliths at Waun Mawn, along...
The doleritic bluestone monoliths at Stonehenge have long been known to have been sourced from the Mynydd Preseli area in west Wales, some 225 km away. On geochemical grounds, based on a range of major and trace elements determined by laboratory-based X-ray fluorescence spectrometry, they have been divided into three groups (Groups 1–3). Subsequent...
The Altar Stone at Stonehenge in Wiltshire, UK, is enigmatic in that it differs markedly from the other bluestones. It is a grey–green, micaceous sandstone and has been considered to be derived from the Old Red Sandstone sequences of South Wales. Previous studies, however, have been based on presumed derived fragments (debitage) that have been iden...
The doleritic bluestones of Stonehenge, sourced from the Mynydd Preseli in west Wales, have been previously classified into three geochemical groups on the basis of compatible element geochemistry (Bevins et al., 2014). The majority of Group 1 (spotted) dolerites were identified as coming from the outcrop of Carn Goedog, Group 3 (spotted) dolerites...
Provenancing the Stonehenge non-spotted dolerites on the basis of REE geochemistry
The discovery of a dismantled stone circle—close to Stonehenge's bluestone quarries in west Wales—raises the possibility that a 900-year-old legend about Stonehenge being built from an earlier stone circle contains a grain of truth. Radiocarbon and OSL dating of Waun Mawn indicate construction c. 3000 BC, shortly before the initial construction of...
Stonehenge is dominated by the large, locally derived sarsen stones which comprise the Outer Sarsen Circle and the Inner Sarsen Trilithon Circle. Lithologically they are a hard form of sandstone called silcrete. Less obvious are the smaller ‘bluestones’ which form the Outer Bluestone Circle and Inner Bluestone Horseshoe. The bluestone assemblage is...
The results and implications of the provenancing of the Stonehenge bluestones and the discovery of two bluestone quarries in west Wales
A review of the provenance of the Altar Stone from Stonehenge and implications for transport of the bluestones to Stonehenge
Geologists and archaeologists have long known that the bluestones of Stonehenge came from the Preseli Hills of west Wales, 230km away, but only recently have some of their exact geological sources been identified. Two of these quarries—Carn Goedog and Craig Rhos-y-felin—have now been excavated to reveal evidence of megalith quarrying around 3000 BC...
Geologists and archaeologists have long known that the bluestones of Stonehenge came from the Preseli Hills of west Wales, 230km away, but only recently have some of their exact geological sources been identified. Two of these quarries—Carn Goedog and Craig Rhos-y-felin—have now been excavated to reveal evidence of megalith quarrying around 3000 BC...
The long-distance transport of the Stonehenge bluestones from the Mynydd Preseli area of north Pembrokeshire was first proposed by geologist H.H. Thomas in 1923. For over 80 years, his work on the provenancing of the Stonehenge bluestones from locations in Mynydd Preseli in south Wales has been accepted at face value. New analytical techniques, alo...
Presentation of bluestone provenancing research
How and why the bluestones arrived at Stonehenge, the UK's most revered ancient monument, has long held people's imagination. The key to understanding these questions relies heavily on the location of their sources. Following early studies in the late eighteenth and early nineteenth centuries, which proposed various places but in particular south-w...
The three major groups of debitage found in the Stonehenge Landscape are dolerites, rhyolitic tuffs (almost exclusivelyfrom Craig Rhosyfelin, now designated as Rhyolite Group A–C) and ‘volcanics with sub-planar texture’ now designatedas Volcanic Group A and Volcanic Group B. The only other significant debitage group, but only accounting for about5%...
New U–Pb zircon ages from rhyolite samples of the Fishguard Volcanic Group, SW Wales, confirm a Middle Ordovician (Darriwilian) age for the group. One of the samples is from Craig Rhos-y-felin, which has recently been identified on petrological and geochemical grounds as the source of much of the debitage (struck flakes) at Stonehenge. Analysis of...
Highlighting the top 100 great geosites in the UK and Ireland
The long-distance transport of the bluestones from south Wales to Stonehenge is one of the most remarkable achievements of Neolithic societies in north-west Europe. Where precisely these stones were quarried, when they were extracted and how they were transported has long been a subject of speculation, experiment and controversy. The discovery of a...
The Fishguard Volcanic Group represents an excellently preserved example of a volcanic sequence linked to the closure of the Iapetus Ocean. This study re-examines the petrogenesis and proposed tectonic setting for the Llanvirn (467–458 Ma) Fishguard Volcanic Group, South Wales, UK. New major and trace element geochemical data and petrographic obser...
The Stonehenge bluestones were first sourced to outcrops in the high parts of the eastern Mynydd Preseli in SW Wales by H.H. Thomas in the early 1920s. He recognised the distinctive ‘spotted dolerite’ from his fieldwork in that area and suggested that the tors of Carn Meini (also known as Carn Menyn) and Cerrigmarchogion were the most likely source...
The Stonehenge bluestones were first sourced to outcrops in the high parts of the eastern Mynydd Preseli in SW Wales by H.H. Thomas in the early 1920s. He recognised the distinctive ?spotted dolerite? from his fieldwork in that area and suggested that the tors of Carn Meini (also known as Carn Menyn) and Cerrigmarchogion were the most likely source...
New concepts in the management of museum natural science collections - moving towards the concept of a distributed collection
The source of the Stonehenge bluestones was first determined in the early 1920s by H.H. Thomas who was an officer with the Geological Survey of England and Wales. He determined that the so-called ‘spotted dolerites’ could be petrographically matched to a small number of outcrops in the Mynydd Preseli district in south-west Wales. The bluestones, ho...
Provenancing the source of the Stonehenge bluestones
The role of museums as agents of culture, education and even nationhood is widely recognised. However, the potential for museums to contribute to regeneration processes is also important. Urban development literature has demonstrated the importance of creative capital in economic development processes. Then, evaluating museums in economic terms, co...
The source of the bluestone component found in the Stonehenge landscape has long been the subject of great interest and considerable debate. The bluestones are a mix of lithologies, the standing orthostats being predominantly dolerites, variably ‘spotted’, with only four of them being of dacitic and rhyolitic composition and the Altar Stone being s...
The source of the bluestones at Stonehenge has long been debated, and while there is general consensus that the so-called spotted dolerites are derived from a relatively small number of outcrops exposed in the highest parts of Mynydd Preseli, in southwest Wales the source of the rhyolitic component has attracted relatively little detailed attention...
Evaluating the significance of mineral parageneses in very
low grade metabasites
IntroductionRegional low-grade metamorphismSubaerial flood basalt sequencesConvergent settingsConclusions
Review of progress in understanding low grade metamorphic mineral parageneses in metabasites
Abstract Mafic phyllosilicates in metabasites affected by low-grade regional metamorphism from Wales and eastern North Greenland show variations in their structure and chemistry. These variations are related to four mineral zones in these metabasites, which are recognized on the presence/absence of various key calc-silicate minerals and also actino...
The Fishguard Volcanic Complex represents an important volcanic episode which occurred within the Welsh sector of the British Caledonide region during early Ordovkian times. A variety of extrusive and contemporaneous intrusive rocks are present, ranging in composition from basic, through intermediate to acidic. Mineral and whole-rock chemical analy...
The metamorphic character of metabasites of the Precordillera terrane of western Argentina provides constraints which help to distinguish between contrasting models for the tectonic settings during the late stages of the accretion of this terrane onto the margin of Gondwana in late Lower Palaeozoic times. Metamorphic conditions are constrained to a...
The Jurassic to Miocene sequences of the central Andes, east of Santiago, reputedly show repeated cycles of episodic sub-greenschist facies, burial metamorphism that are identified by sharp breaks in metamorphic grade at major stratigraphic boundaries. This paper presents the first detailed petrochemical analysis of these low-grade metamorphic sequ...
Fluid inclusion and stable isotope data from quartz and carbonate minerals in fracture fillings and ‘ironstone’ nodules from the South Wales Coalfield have been used to characterise the fluids generated during basin evolution and associated coalification. Carbonates grew first, probably at relatively shallow depths and low temperatures (<100°C). Th...
La Salvadora ore deposit (35degrees21' 16"S; 68degrees23'22"W), located in the Province of Mendoza, Argentina, is part of a group of polymetallic veins linked to a porphyry copper that shows a crude temperature zonation away from the potassic centre. This porphyry deposit is genetically related to Lower Permian volcanic rocks from a subduction tect...
Burial metamorphism of regional extent throughout Mesozoic to Cenozoic sequences in the Andean Mountain belt has been attributed previously to a unique model of metamorphic development, involving episodic ˜40 m.y. cycles of extensional basin formation, burial, metamorphism, and then exhumation. A main premise of this model is that breaks in metamor...
The Central Andes of Chile are characterized by subgreenschist facies burial metamorphism that is reported as having developed in up to seven episodic cycles of some 40Myr duration. The main evidence in support of the model is reported as mineralogical breaks at major stratigraphic boundaries that are interpreted as documenting sharp breaks in meta...
The auriferous quartz-sulphide veins of the Dolgellau gold belt represent the finest example of a pre-Acadian, mesothermal gold-lode metallogenic province in the United Kingdom. The gold lodes are composite, multi-stage, ribbon-quartz bodies occupying shear zones in clastic marine sedimentary rocks, including black mudstones, of Middle to Upper Cam...
Slow precipitation experiments have been used to determine the oxygen isotope fractionation between cerussite (PbCO3) and water over the temperature range 20 to 65°C. The temperature dependent fractionation for oxygen can be expressed as: Independent determinations of the oxygen isotope fractionation factor for recent historical cerussite samples f...
Slow precipitation experiments have been used to determine the oxygen isotope fractionation between cerussite (PbCO 3) and water over the temperature range 20 to 65°C. The temperature dependent fractionation for oxygen can be expressed as: 1000 ln (cerussiteCO 3-water) 2.63 (10 6 /T 2) 3.58 Independent determinations of the oxygen isotope fractiona...
Calc‐alkaline basic volcanic rocks in a c. 600 m thick sequence of Miocene age, the Valle Nevado stratified sequence (VNSS), have been affected by very low grade metamorphism characterised by mineral assemblages of the zeolite facies. Metastable conditions prevailed, most of the igneous minerals being wholly or partially preserved. The main metamor...
The Lower Paleozoic Welsh Basin of the U.K. Caledonides shows a metamorphic transition from zeolite to low-greenschist facies for which there are two radically opposing models of development. The traditional model is of a syntectonic metamorphism associated with crustal thickening during basin inversion and cleavage development. The alternative mod...
Quartz-sulphide veins that cut Middle to Upper Cambrian sedimentary and intrusive rocks in coastal exposures at Friog, south of Fairbourne, Gwynedd, Wales, show features consistent with Acadian deformation, including folds, boudins and cleavage. In the closely adjacent Dolgellau gold belt abundant quartz-sulphide veins, some of which are auriferous...
In Great Britain we now have a reasonable analysis of the importance of geological sites at a national and local level, through the GCR and some second-tier recording (National Scheme for Geological Site Documentation - NSGSD; Regionally Important Geological Sites - RIGS), but there has been no similar analysis at an international level. Internatio...
metamorphic alteration of low grade metamorphic rocks in eastern Switzerland
Localized (domainal) low-temperature alteration may indicate variations in the chemistry of alteration fluids and/or discrete fluid flow paths during metamorphism. Occurrences of epidote- and pumpellyite-dominated domains are often used as evidence for large fluxes of Ca-rich fluids. However, comparative studies of two domainal alteration styles fr...
The South Wales Coalfield comprises Namurian, Westphalian and Stephanian sequences which developed in the external zone of the Variscan Orogenic Belt. Sedimentation is thought to have been concentrated in a paralic basin related to crustal flexure in a foreland basin setting, linked to Variscan tectonic loading to the south. It has long been recogn...
Siderite nodules in the Carboniferous Coal Measures of South Wales contain cavities which are often infilled with quartz, carbonates, sulphides, and hydrocarbons. The quartz contains a mixture of hydrocarbon and aqueous fluid inclusions. The aqueous fluid inclusions consist of a dilute brine (3 wt % NaCl equivalent) and have homogenization temperat...
The Berw and Aber-Dinlle Faults represent the brittle manifestation of a major lineament, the Menai Strait Fault System, which is known to have been active intermittently since late Precambrian times. Documentation of historical seismicity in this area provides information on the most recent activity along this structure, although there is a paucit...
Volcanic rocks of Neoproterozoic age form several fault-related inliers in Wales and the Welsh Borderland. Those in North Wales and the Borderland have been investigated recently, while those in southwest Wales remain little studied. In southwest Wales, basic to intermediate lavas and related volcaniclastic rocks and silicic tuffs in the St David’s...
The Geological Conservation Review (GCR) was intended to be an inventory and justification of the best in geological field sites, a reflection of the rich geological heritage for which Britain is internationally famous. At its inception in 1975, and more particularly from early 1978 when proper funding started, the GCR project's aim was to revise i...
