Asymmetry in an uneven place: migrants’ lifestyles,social capital,and self-rated health status in James Town,Accra

This exploratory study examines how migrants’ lifestyles are associated with subjective assessment of their health status in a relatively poor urban neighborhood in Accra. For more than half a century, urban centers have been on the receiving end of internal migrants in Ghana with Accra, Kumasi, and Sekondi-Takoradi receiving the lion’s share. However, a lot of migrants end up in poor neighborhoods due to inability to afford relatively costly rents in the better residential areas in the cities. Migrants who live on the margins of society are adversely impacted by poor environmental conditions that make them susceptible to environmentally-induced diseases such as malaria, cholera, and typhoid. While the poverty, health, and place research in Accra, Ghana, have focused on spatial distribution of inequalities in health, burden of sexual ill health, double burden of diseases, environment, wealth and health relationship, as well as income and health connections, there is paucity of research on association between the daily lifestyles of migrants in poor urban neighborhoods and their health status. Specifically on lifestyle and contextual factors, we examine (1) eating and drinking behavior, (2) perception of environmental factors, (3) attitudes and practices during illnesses, and (4) physical activities. Results from Ordinal Logit Regression models suggest that the key predictors of self-rated health status are: (1) socio-demographic elements like length of stay, job type, and religiosity; and (2) eating and drinking behavior—frequency of buying food from food vendors, and (3) social capital.     

Selling green militarization: The discursive (re)production of militarized conservation in the Virunga National Park,Democratic Republic of the Congo

In recent years, the militarization of nature conservation has intensified, especially in protected areas located in conflict zones or plagued by ‘poaching crises’. Such ‘green militarization’ is enabled by a range of discursive techniques that allow it to be seen as a ‘normal’ and ‘legitimate’ response. This article analyzes these techniques in relation to the Virunga National Park, located in the war-ridden east of the Democratic Republic of the Congo, where militarized approaches to conservation have a long lineage. It demonstrates that many of the discursive techniques that are currently at play show strong continuities with the past. These include moral boundary-drawing grounded in colonial tropes that accomplish the (racial) Othering of poachers and rebels, and the long-established practice of invoking states of emergency as part of wider mechanisms of securitization. However, the rise of neoliberal conservation, with its emphasis on marketing and marketization, has induced transformations in the employed discursive techniques. Notably, it has intensified the spectacularization of militarized conservation and anchored it in everyday consumer practices, by actively inviting individual supporters to directly fund militarized interventions, thus generating ‘militarization by consumption’. This shows that ‘green militarization’ is not only driven by the growing commodification of nature conservation, but is increasingly subject to commodification itself.     

Geographies of citizenship and everyday (im)mobility

This introduction and the collection of papers it introduces seek to progress debates on the intersections between citizenship, practice, materiality, and mobility. In contrast to more static framings of formal citizenship where subjects are considered equal in terms of enjoying the same safeties and freedoms, in this introduction citizenship is conceived of as a set of processual, performative and everyday relations between spaces, objects, citizens and non-citizens that ebbs and flows. Through the papers that comprise this collection we see the process of citizenship becoming fragmented in both urban and rural mobility spaces. We also see it as being shaped by particular technologies and artefacts which construct and relate mobile subjects to each other and the state in particular ways. Our key contribution lies in outlining three related areas where work informed by the mobilities turn could focus: Firstly we seek to demonstrate that far from being a product of citizenship status, mobility must be seen as actively constituting citizenship relations. Secondly we seek to demonstrate the roles that styles of movement and the ‘stuff’ of mobility play in shaping the extent of citizenship for particular mobile publics. Thirdly we illustrate the ways in which cross-border flows relating to concepts such as cosmopolitan and ecological citizenship can act through mobility practices to challenge locally held notions of appropriate mobility and inevitably citizenship. Ultimately what we argue and intend to demonstrate is that mobility is such an important, pervasive and politicised element of late modernity that the ways in which we move and confer meanings on movement, cut across and even over-ride more established relationships between social and cultural identity, citizenship and the state.     

Reassessment of the ‘Abbevillien’ in the perspective of new discoveries from the Lower Palaeolithic and Quaternary sites of Abbeville (Somme,northern France)

North-West Europe yields few traces of early human occupation, in particular for the Acheulean. In this context, the Somme Valley in northern France offers a route to Britain during various Pleistocene low sea levels, and has provided numerous evidence of Lower Palaeolithic human occupation through fieldwork initiated during the 19th century. These localities are associated with the original definition in the 1930s by the French prehistorian Abbé Henri Breuil of the ‘Abbevillien’ (Abbevillian facies), based on lithic pieces including crudely made bifaces recovered in particular in some famous key localities of Abbeville, Carpentier, Léon and Moulin Quignon quarries. The history of the term and its definition subsequently gave rise to debates concerning the chronocultural framework of Palaeolithic assemblages among the scientific community of prehistorians over time, from Jacques Boucher de Perthes, Gabriel de Mortillet, Geoffroy d'Ault du Mesnil, Victor Commont, Henri Breuil and François Bordes. New investigations at these three localities, all associated with the High Terrace of the Somme system, pushed back the age of the expansion of the Acheulean both in northern France and in Western Europe to c. 670–650 000 years. They imply that early hominins were able to settle in North-West Europe during both climatic temperate and cold phases. Our work, including new excavations and associated field observations of the three Abbeville localities involved at the onset of the controversy, allows a re-examination of the Abbevillian and contributes to the discussion of the history of Prehistoric Science and the Earliest ‘Acheuleans’ in North-West Europe.     

Producing ‘prehistoric’ life: Conservation breeding and the remaking of wildlife genealogies

The giant tortoises of the Galápagos Islands, a species Charles Darwin called ‘antediluvian,’ are the focus of one of the world’s most successful conservation breeding programs. This paper explores the paradox of the breeding program, examining how ‘prehistoric’ life has been actively produced through nearly a century of work by scientists and conservationists dedicated to saving this endangered species. It traces the story of one giant tortoise, Diego, who was collected from the archipelago in the 1930s, lived in an colony at the San Diego Zoo for forty years, and returned to the Galápagos in 1977, where he became the star stud of the breeding program. I argue that the giant tortoises are not icons of a ‘pristine’ evolutionary history, but are the product of genealogies that enfold management practices in the bodies and bloodlines of wildlife. The paper focuses on the assemblages of reproduction at the center of these genealogies, drawing attention to the multiple agencies and spatialities that emerge in practices of experimentation – first at the zoo, where keepers struggled to keep the giant tortoise colony alive and healthy, and then in the Galápagos, where conservationists were eventually able to gain enough control over tortoise reproduction to standardize and replicate breeding practices. The case extends readings of conservation as a field of nonhuman biopolitics by attending to the production of wildlife itself as a strategy that facilitates the reproduction of conservation and tourism in the archipelago.     

Aeolian origin and palaeoclimatic implications of the ‘red clay’ (north China) as evidenced by grain‐size distribution

The ‘Red Clay’ is an important deposit underlying the Quaternary loess–palaeosol sequence in the Chinese Loess Plateau, being regarded as an excellent record of palaeoclimate changes in the late Tertiary. Several properties of the ‘Red Clay’ have been measured previously in order to derive climatic information. However, the sedimentary processes involved and the origin of the materials remain controversial. Here we present results of grain‐size analyses of the ‘Red Clay’ from four representative sites in the Chinese Loess Plateau. In particular their grain‐size distribution is compared with that of typical Quaternary aeolian loess–palaeosol, as well as lacustrine and fluvial sediments. It appears from the sedimentological evidence that the major part of the ‘Red Clay’ is of aeolian origin. It is rather similar in some of its properties to the Quaternary loessic palaeosols. The dust forming the ‘Red Clay’ was transported by a wind system that was weaker than that involved in the accretion of the Quaternary loess. Furthermore, the ‘Red Clay’ sediment has been modified by post‐depositional weathering. Copyright © 2001 John Wiley & Sons, Ltd.     

Fission-track constraints on the thermal and tectonic evolution of the Apuseni Mountains (Romania)

New zircon and apatite fission-track (FT) data, including apatite thermal modelling, are combined with an extensive literature survey and reconnaissance-type structural fieldwork in the Eastern Apuseni Mountains. This leads to a better understanding of the complex structural and thermal history of a key area at the boundary between two megatectonic units in the Balkan peninsula, namely the Tisza and Dacia Mega-Units. Following Late Jurassic obduction of the Transylvanian ophiolites onto a part of the Dacia Mega-Unit, that is, the Biharia nappe system, both units were buried to a minimum of 8 km during late Early Cretaceous times when these units were underthrust below the Tisza Mega-Unit consisting of the present-day Codru and Bihor nappe systems. Tisza formed the upper plate during Early Cretaceous (‘Austrian’) east-facing orogeny. Turonian to Campanian zircon FT cooling ages (95–71 Ma) from the Bihor and Codru nappe systems and the Biharia and Baia de Arie? nappes (at present the structurally lowest part of the Dacia Mega-Unit) record exhumation that immediately followed a second Cretaceous-age (i.e. Turonian) orogenic event. Thrusting during this overprinting event was NW-facing and led to the overall geometry of the present-day nappe stack in the Apuseni Mountains. Zircon FT ages, combined with thermal modelling of the apatite FT data, show relatively rapid post-tectonic cooling induced by a third shortening pulse during the latest Cretaceous (‘Laramian’ phase), followed by slower cooling across the 120°–60 °C temperature interval during latest Cretaceous to earliest Paleogene times (75–60 Ma). Cenozoic-age slow cooling (60–40 Ma) was probably related to erosional denudation postdating ‘Laramian’ large-scale updoming.     

Interaction between seismic and volcanic deformation: a possible interpretation of ground deformation observed at Vulcano Island (1976–84)

Levelling measurements carried by Osservatorio Vesuviano over Vulcano Island (North Sicily) since June 1976 show a complex history of small but significant vertical movements which took place after the ‘Patti earthquake’ of 15/4/1978. Three phases can be identified in the time history of ground deformation: (I) co-seismic subsidence of the northern part of the Island with respect to the southern part, followed by (II) transient inflation of the central region surrounding ‘La Fossa’ volcano, and finally (III) deflation and subsidence to stationary values greater than phase I. Large variations in temperature and gas content of magmatic origin were also detected in fumaroles along the crater rim of ‘La Fossa’. The coincidence in time of the earthquake with the start of the deformation history, the proximity of the event to Vulcano Island and the favourable mechanism (right lateral) and orientation (NNW) of the fault strike, suggest that the earthquake triggered the observed deformation. Among the plausible models, one seems particularly able to reproduce the amplitude and time evolution of the geodetic data, in a manner consistent with the geochemical observations. According to this model the earthquake, while generating a compressive stress field in the quadrant of Vulcano Island, induced at first a relative coseismic subsidence of the northern part of the island, accompanied by a large increase of the mean stress within a magma chamber at ～ 6.5 km depth. Volatile fluids were then released from the top of the magma chamber and migrated towards the surface following the enhanced pressure gradient. As a result fluid pressure diffusion around the magma chamber induced a local transient uplift of ground that vanished after exhaustion of the overpressure at the source, and finally left a permanent dislocation deformation, possibly amplified by the post-seismic relaxation of the earthquake deviatoric stress. This interpretation is qualitatively consistent with the one suggested by Ferri et al. (1988).     

Lower Palaeolithic artefacts in surface contexts in Britain with special reference to the Northern Drift (Oxfordshire) and Warren Hill (Suffolk)

The processes of surface clast dispersal are discussed and it is shown that on flat land the spatial integrity of larger gravel clasts (which include most diagnostic artefacts) is likely to be preserved over long periods. A structured approach is described for predicting land surfaces where Lower Palaeolithic artefact scatters may have survived through the British Quaternary. The topographic map of Britain is subjected to three tests to eliminate areas unlikely to preserve these surfaces. After progressively subtracting glaciated areas, areas covered by superficial deposits, and river basins/areas with slopes steeper than about 2°, the surfaces remaining have the potential for long-term stability. Eight criteria are described to help verify true palaeosurfaces. They comprise mostly high level plateau lands. On to this map are plotted fifteen sample localities known to have yielded Lower Palaeolithic artefacts from surface contexts. Ten lie within the predictive model, the remainder belong to surface fluvial deposits or other superficial deposits. Four sites have been mapped in enough detail to show the distribution of individual artefacts; in three, traces of clustering occurs, suggesting the original scatter patterns have not entirely dispersed in time. The two sites of Warren Hill and the Northern Drift where the author has worked are examined in more detail. Comparison is made with a ‘pristine’ Early/Middle Stone Age surface site from arid terrain in Namibia. It is argued that in certain circumstances even in the volatile British climate surface scatters may not have moved far from their original location. The predictive map can only be a general guide: each site is different, but clay-with-flints has ubiquitous potential. Surface studies include both flint and quartzite artefacts, with their contrasting typologies. It is concluded that surface studies are likely to lead to a more complete understanding of early human occupation patterns.     

A cystoid with two left facets: the significance of Tetracystis in the evolution and classification of the Callocystitidae (Echinodermata,Glyptocystitoida)

Revision of some North American Silurian callocystitid cystoids shows that Tetracystis Schuchert has the first two brachioles to the left in ambulacra B and D (B D different pattern), whereas Troosticystis Paul and Lovenicystis Regéll have only the first brachiole to the left in all four ambulacra (B–E the same pattern). ‘Apiocystites’ elegans Hall is transferred to Tetracystis because it has the B D different pattern. Lovenicystis kopfi sp. nov. is characterized by four short ambulacra. Salirocystis gen. nov. has the B D different pattern and two hydropores. All callocystitids that lack ambulacrum A are assigned to a new subfamily, the Tetracystinae; those with five ambulacra are referred to informally as ‘lepadocystines’. The previously recognized subfamily Callocystitinae is reduced in rank to a tribe within the ‘lepadocystines’. Preliminary character analysis suggests that the loss of ambulacrum A was the most significant evolutionary event within the family Callocystitidae, but has been overlooked in taxonomy. Character analysis also shows that all ‘lepadocystines’ had the B D different pattern of primary brachioles, which is retained in four tetracystine genera, Lepocrinites Conrad, Sphaerocystites Hall, Tetracystis and Salirocystis. Since Salirocystis has the plesiomorphic B D different pattern plus the apomorphic double hydropore, one cannot define a monophyletic taxon characterized by the B–E the same pattern plus one characterized by a double hydropore. Both alternatives are equally parsimonious. Here a new monophyletic tribe Lipsanocystini is defined characterized by a double hydropore. The B–E the same pattern evolved independently twice. Among current characters the loss of ambulacrum A, development of the B–E the same pattern and development of two hydropores are the most significant evolutionary events. Number of periproct border plates, length and structure of ambulacra are less significant. Copyright © 2014 John Wiley & Sons, Ltd.     

Hydrothermal alteration vs. ocean-floor metamorphism. A comparison between two case histories: the TAG hydrothermal mound (Mid-Atlantic Ridge) vs. DSDP/ODP Hole 504B (Equatorial East Pacific)

This article presents a review of hydrothermal alteration of the various basaltic rocks forming the oceanic crust, emphasizing especially on the water–rock interaction processes, the petrography and secondary mineralogy of hydrothermally altered rocks from the present-day ocean, hence excluding the ophiolitic complexes. A brief summary of the history of the first studies of hydrothermally altered oceanic rocks leads to a comparison between Miyashiro's concept of ‘ocean-floor metamorphism’ and that of hydrothermal alteration that warrant caution when applying Eskola's metamorphic facies of regional metamorphism to hydrothermally altered oceanic rocks. The functioning of mid-oceanic ridge axial hydrothermal systems, and the role of oceanic Layer-3 gabbros are discussed in detail. The mechanisms of the various alteration processes of the rocks forming the oceanic crust are presented. The case histories of the two examples more particularly studied by the author and his collaborators, are compared, i.e., the DSDP-ODP Hole 504B reference section South of the Costa Rica Ridge, and the TAG active mound at the Mid-Atlantic Ridge. The significance of the paragonitic phyllosilicate in highly altered rocks form the TAG Mound is compared to the other known occurrences of ‘white micas’ in the oceanic crust. The importance of metabasites as major components of the oceanic crust is emphasized. The elemental fluxes resulting from hydrothermal alteration of oceanic rocks in regulating seawater chemistry are only briefly alluded, because this topic is covered by the last article of this thematic issue by J.C. Alt, who assesses the chemical budgets resulting from ocean hydrothermal activity. To cite this article: J. Honnorez, C. R. Geoscience 335 (2003).     

‘Boninitic’ clasts from the Mesozoic olistostromes and turbidites of Angelokastron (Argolis,Greece)

The Lower Unit of the ophiolitic sequence of Northern Argolis comprises turbiditic sediments and olistostromes, both containing ophiolitic clasts, mainly crystal fragments (clinopyroxene, plagioclase, Cr-spinel, amphibole) in the turbidites and cumulitic intrusives (quartz noritic amphibole-bearing gabbros), subvolcanic rocks (dolerites) and various effusive lithologies (mainly Si-rich basalts to basaltic andesites) in the olistostromes. The volcanic rocks belong to three groups. In rare cases the lavas are mineralogically and chemically comparable with MORB; most of them, and the subvolcanic rocks, contain primary quartz and amphibole, orthopyroxene, Ca-rich plagioclase and clinopyroxene±Cr-spinels. All rocks are Si- and Mg-rich and have high concentrations of ‘compatible’ and very low concentrations of ‘incompatible’ elements. The REE profiles are characteristically U-shaped. Many of the observed features are comparable with those of subduction-related lavas and, in particular, with present day boninites and ophiolitic boninitic rocks. The gabbroic rocks have mineralogical and chemical analogies with the dolerites and lavas, thus it may be argued that the gabbros represent the intrusive counterparts of the ‘boninitic’ volcanic clasts. The mineral clasts occurring in the turbidites are chemically comparable with those analysed in the ophiolitic clasts of the overlying olistostrome. It may be concluded that the ophiolitic clasts of both olistostromes and turbidites were derived from a subduction-related sequence. An island arc–back-arc system might explain the occurrence of both boninitic and MORB-type lithologies in the olistostrome of Angelokastron. This may support the hypothesis of the onset of compressive tectonics along the Pindos Ocean during the Jurassic. © 1996 John Wiley & Sons, Ltd.     

The lower carboniferous (dinantian) of the Swords area: Sedimentation and tectonics in the Dublin Basin,Ireland

The litho- and biostratigraphy of the Lower Dinantian succession in a deeper part of the Dublin Basin is described. The sub-Waulsortian Malahide Limestone Formation (emended) is described fully for the first time, and has proved to be very much thicker than was previously suspected, in excess of 1200 m. Succeeding the ‘Lower Limestone Shale’ unit, which is transitional from the underlying Old Red Sandstone facies, the following six new members are recognized: Turvey Micrite Member, Swords Argillaceous Bioclastic Member, St. Margaret's Banded Member, Huntstown Laminated Member, Dunsoghly Massive Crinoidal Member and Barberstown Nodular Member (top). The Malahide Limestone Formation is overlain by ‘Waulsortian’ limestones of the Feltrim Limestone Formation (new name) which form overlapping and isolated mudmounds with complex relationships with their enclosing non-mound facies. Though very much thicker, the Courceyan succession is comparable with that elsewhere on the south side of the Basin, and is part of the Kildare Province (Strogen and Somerville 1984). Isopach maps for the region show that this province and the North Midlands are separated by the deepest part of the Dublin Basin, named the ‘East Midlands Depocentre’, in which a shale-dominant facies is present. The top of the ‘Waulsortian’ is of early Chadian age. Formations younger than this are dominated by basinal calcareous shales (Tober Colleen Formation) and by storm deposits and calciturbidites with appreciable terrigenous input from the east (Rush Formation). The Courceyan main shelf conodont biozones are also greatly thickened in this area. The Pseudopolygnathus multistriatus Biozone (> 300 m thick) is succeeded by a very thick (> 900 m) Polygnathus mehli Biozone. The base of the Chadian is considered to occur below the top of the Feltrim Limestone Formation and, although equivocal, may be diagnosed in the Dublin Basin by the first appearance of the problematic microfossil Sphaerinvia piai and a primitive form of the calcareous alga Koninckopora. In the late Courceyan, the Swords area was part of a gently sloping shelf extending northwards into the basin. During deposition of the Feltrim Limestone Formation there was major deepening and there is evidence of initial break up of the Dublin Basin by faulting into separate blocks. By Chadian time the Basin was definitely subsiding by fault displacements and basinal limestones contain shallow water faunas and littoral sand and pebbles derived by turbidite flows from the margins of the higher blocks. The early subsidence was apparently by pure flexure, but in the Viséan the Dublin Basin was fault-controlled, differing from the adjacent Shannon Basin in having both margins strongly faulted.     

Assessment of groundwater vulnerability based on a modified DRASTIC model, GIS and an analytic hierarchy process (AHP) method: the case of Egirdir Lake basin (Isparta, Turkey)

A DRASTIC-model method based on a geographic information system (GIS) was used to study groundwater vulnerability in Egirdir Lake basin (Isparta, Turkey), an alluvial area that has suffered agricultural pollution. ‘Lineament’ and ‘land use’ were added to the DRASTIC parameters, and an analytic hierarchy process (AHP) method determined the rating coefficients of each parameter. The effect of lineament and land-use parameters on the resulting vulnerability maps was determined with a single-parameter sensitivity analysis. Of the DRASTIC parameters, land use affects the aquifer vulnerability map most and lineament affects it least, after topography. A simple linear regression analysis assessed the statistical relation between groundwater nitrate concentration and the aquifer vulnerability areas; the highest R ² value was obtained with the modified-DRASTIC-AHP method. The DRASTIC vulnerability map shows that only the shoreline of Egirdir Lake and the alluvium units have high contamination potential. In this respect, the modified DRASTIC vulnerability map is quite similar. According to the modified-DRASTIC-AHP method, the lakeshore areas of Senirkent-Uluborlu and Hoyran plains, and all of the Yalvaç-Gelendost plain, have high contamination potential. Analyses confirm that groundwater nitrate content is high in these areas. By comparison, the modified-DRASTIC-AHP method has provided more valid results.     

A comparative study of the thermal behaviour of length-fast chalcedony, length-slow chalcedony (quartzine) and moganite

The thermal behaviour of silica rocks upon heat treatment is dependent on the constituent minerals and petrographic texture types. These constituents can be shown to be mainly quartz in the form of two types of chalcedony (Length-fast (LF) chalcedony and Length-slow (LS) chalcedony, the latter also being termed quartzine) and moganite. Even though the thermal behaviour of LF-chalcedony is well understood, major uncertainties persist concerning the high-temperature behaviour of LS-chalcedony and moganite. We present here a comparative study of these three constituents of common silica rocks. Our results show that the chemical reaction is the same in all three, Si–OH + HO–Si → Si–O–Si + H₂O, but that the reaction kinetics and activation temperatures are very different. LS-chalcedony begins to react from 200 °C upwards, that is at temperatures 50 °C below the ones observed in LF-chalcedony, and shows the fastest reaction kinetics of this ‘water’ loss. Chemically bound water (SiOH) in moganite is more stable at high temperatures and no specific activation temperature is necessary for triggering the temperature-induced ‘water’ loss. Moganite is also found to act as a stabilizer in silica rocks preventing them from temperature-induced fracturing. These findings have implications for the study of potential heat treatment temperatures of silica rocks (in industry and heritage studies), but they also shed light on the different structures of SiO₂ minerals and the role of OH impurities therein.     

Stratigraphie et sédimentologie des « calcaires à Productus » du Carbonifère inférieur de la Montagne noire (Massif central,France)Stratigraphy and sedimentology of the Lower Carboniferous ‘Calcaires à Productus’ of the Montagne Noire (Massif Central,France)

The ‘Calcaires à Productus’ of the Montagne Noire are microbial build-ups. Two formations are defined and dated respectively as Uppermost Visean (Upper Warnantian–Brigantian) and Serpukhovian on the basis on corals. That makes these limestones out to be younger than previously stated (Lower and base of Upper Warnantian–Asbian and base of Brigantian) and indicates that the development of the olistoliths and thrusts including them, due to the Variscan orogeny, was at least as young as the Upper Serpukhovian. The Serpukhovian limestones of the Montagne Noire are correlated with the Lanet Limestone (Mouthoumet Massif, Corbières) and Ardengost Limestone (central Pyrenees). To cite this article: É. Poty et al., C. R. Geoscience 334 (2002) 843–848.     

Physical geology of the Fogo volcano (Cape Verde Islands) and its 2014–2015 eruption

The geological development of the Fogo island volcano commenced in the early Quaternary, and much later during the Last Glacial stage this involved a mega‐scale lateral collapse of the former edifice. This later event created a large caldera‐like landform open to the east, the floor of which is known as the Chã, and subsequently within this a strato‐volcanic cone has grown. The last phase of volcanic activity started in late 2014 and persisted for 77 days. It had a devastating impact on the lives of the 1000 plus people who were living within the ‘caldera’, since two large villages and a smaller one were each totally destroyed in a matter of days by the advancing lavas. In addition, large areas of cultivated land, upon which the inhabitants were dependent for their livelihood, were enveloped by lava. The eruption proved to be of a greater magnitude than the immediately preceding one of 1995, when a mass evacuation was necessary but as only a few buildings were affected, resettlement followed. Unfortunately the much greater devastation to the human environment makes it doubtful whether any significant resettlement will be possible after the 2014–2015 event.     

Geodiversity and the ‘8Gs’: a response to Brocx & Semeniuk (2019)

Abstract

Brocx and Semeniuk’s (2019 Brocx, M., & Semeniuk, V. (2019). The ’8Gs’ – a blueprint for geoheritage, geoconservation, geo-education and geotourism. Australian Journal of Earth Sciences, 66(6), 803–821. doi:10.1080/08120099.2019.1576767[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) paper is discussed, particularly in relation to the concept of geodiversity and their proposed sequence of ‘8Gs’. Their ideas on these topics are at odds with the majority of published papers and Internet sources on geodiversity. We argue that geodiversity as a concept has real value and that (a) the planet’s geodiversity occurs at all scales from global downwards, (b) it deserves an absolutely central place in any sequence of ‘Gs’ since it is the backbone of international and national geoheritage and geoconservation strategies, and the basis for geoheritage assessments, and (c) that as well as underpinning biodiversity, geodiversity is the source of many other geosystem services, including geotourism. Finally, a revised proposal for the relationship between geology, geodiversity, geoheritage, geoconservation and other ‘Gs’ is presented.     

Braided rivers within an arid alluvial plain (example from the Lower Triassic,western German Basin): recognition criteria and expression of stratigraphic cycles

Based on a detailed sedimentological analysis of Lower Triassic continental deposits in the western Germanic sag Basin (i.e. the eastern part of the present‐day Paris Basin: the ‘Conglomérat basal’, ‘Grès vosgien’ and ‘Conglomérat principal’ Formations), three main depositional environments were identified: (i) braided rivers in an arid alluvial plain with some preserved aeolian dunes and very few floodplain deposits; (ii) marginal erg (i.e. braided rivers, aeolian dunes and aeolian sand‐sheets); and (iii) playa lake (an ephemeral lake environment with fluvial and aeolian sediments). Most of the time, aeolian deposits in arid environments that are dominated by fluvial systems are poorly preserved and particular attention should be paid to any sedimentological marker of aridity, such as wind‐worn pebbles (ventifacts), sand‐drift surfaces and aeolian sand‐sheets. In such arid continental environments, stratigraphic surfaces of allocyclic origin correspond to bounding surfaces of regional extension. Elementary stratigraphic cycles, i.e. the genetic units, have been identified for the three main continental environments: the fluvial type, fluvial–aeolian type and fluvial/playa lake type. At the time scale of tens to hundreds of thousands of years, these high‐frequency cycles of climatic origin are controlled either by the groundwater level in the basin or by the fluvial siliciclastic sediment input supplied from the highland. Lower Triassic deposits from the Germanic Basin are preserved mostly in endoreic basins. The central part of the basin is arid but the rivers are supplied with water by precipitation falling on the remnants of the Hercynian (Variscan)–Appalachian Mountains. Consequently, a detailed study of alluvial plain facies provides indications of local climatic conditions in the place of deposition, whereas fluvial systems only reflect climatic conditions of the upstream erosional catchments.     

Geochemistry and isotope (Sr, Nd, O) study of Al–Mg granulites from the In Ouzzal Archaean block (Hoggar, Algeria)

The In Ouzzal Al–Mg granulites are found within sedimentary units deposited after 2.7 Ga, the whole association being metamorphosed under extreme temperature conditions (c. 1000 °C) at 2 Ga. The Al–Mg granulites are interlayered with other metasediments, including metapelites, quartzites and magnetite-bearing quartzites, forsterite-spinel marbles, and a few meta-igneous rocks (mainly pyroxenites). They do not occur at a specific position in the sedimentary suite, and they do not reflect any particular structural control. The major and trace element compositions of Al–Mg granulites (especially the high Cr, Ni, Co contents) show that their peculiar ‘refractory’ chemistry is more compatible with premetamorphic sedimentary characteristics rather than with metasomatic, metamorphic or partial melting processes. Sedimentary admixtures of a common mature detrital component coming from the weathering of the local acidic igneous crustal protoliths (normal pelitic component) with an extremely immature component derived from reworking of basic/ultrabasic lithologies (Al–Mg–Cr–Co–Ni–rich chloritic component) is consistent with the geochemistry of such rocks. As in other instances, the quartz-garnet oxygen isotopic thermometer here records an apparent temperature close to the peak metamorphism (c. 1000 °C). Although the persistence of pre-existing δ¹⁸O variations on a small scale during the metamorphism does not support a major pervasive fluid flow during metamorphism, it does not rule out the presence of syn- to post-metamorphic CO₂. The low δ¹⁸O (c.+ 5 to + 6‰) of the most typical Al–Mg granulites indicate that the ‘chloritic component’ in these rocks was derived from hydrothermally altered mafic/ultramafic protoliths rather than dominantly from palaeosols. It is suggested that the presence of such Al–Mg–Cr–Co–Ni–rich sediments is indirect evidence for the presence of greenstone belts in the local crust of the In Ouzzal at 2.6–2.7 Ga.