Philippe Duringer

Anatomically modern human in Southeast Asia (Laos) by 46 ka

Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51–46 ka, and direct U-dating of the bone indicates a maximum age of ∼63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic–modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ∼50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia.

Late middle Eocene epoch of Libya yields earliest known radiation of African anthropoids

Reconstructing the early evolutionary history of anthropoid primates is hindered by a lack of consensus on both the timing and biogeography of anthropoid origins. Some prefer an ancient (Cretaceous) origin for anthropoids in Africa or some other Gondwanan landmass, whereas others advocate a more recent (early Cenozoic) origin for anthropoids in Asia, with subsequent dispersal of one or more early anthropoid taxa to Africa. The oldest undoubted African anthropoid primates described so far are three species of the parapithecid Biretia from the late middle Eocene Bir El Ater locality of Algeria and the late Eocene BQ-2 site in the Fayum region of northern Egypt. Here we report the discovery of the oldest known diverse assemblage of African anthropoids from the late middle Eocene Dur At-Talah escarpment in central Libya. The primate assemblage from Dur At-Talah includes diminutive species pertaining to three higher-level anthropoid clades (Afrotarsiidae, Parapithecidae and Oligopithecidae) as well as a small species of the early strepsirhine primate Karanisia. The high taxonomic diversity of anthropoids at Dur At-Talah indicates either a much longer interval of anthropoid evolution in Africa than is currently documented in the fossil record or the nearly synchronous colonization of Africa by multiple anthropoid clades at some time during the middle Eocene epoch.

Annalepis zeilleri Fliche 1910 emend., un organe reproducteur de Lycophyte de la Lettenkohle de l'Est de la France. Morphologie, spores in situ et paléoécologie

ZusammenfassungZahlreiche gut erhaltene Sporophylle von Lycophyten wurden bei Wasselonne (Bas-Rhin, Frankreich) in der mittleren Lettenkohle gefunden. Schon 1910 beschriebFliche solche Sporophylle unter dem NamenAnnalepis zeilleri. Dennoch wurden sie bis jetzt übersehen, wegen einer fehlerhaften Interpretation ihrer Struktur und Affinitäten. Diese Sporophylle sind 2,5–4,5 cm lang und 1–2 cm breit. Sie bestehen aus einer dreieckigen Spreite mit langem geflügeltem Blattstiel, der einen großen, zungenförmigen Sporangium adaxial trägt. Je nachdem es sich um Mikrooder Makrosporophylle handelt, enthält das Sporangium kleine monolete Mikrosporen oder große trilete Makrosporen. Diese Sporen kennt man als verstreute Formen unter den entsprechenden Namen vonAratrisporitesLeschik undTenellisporitesPotonie.Die Sporophyllähren müssen sehr groß gewesen sein, da ihr Durchmesser auf mindestens 14 cm abgeschätzt werden kann. Von allen bekannten Ähren mesozoischer Lycophyten sind es die größten, die bis jetzt gefunden worden sind. Ihrer allgemeinen Struktur und ihrer Größe nach ähneln diese Sporophylle der Lettenkohle denen derLepidodendraceae des Karbon, deren Nachkommen sie sein könnten. Dementsprechend stellen wir die Gattung AnnalepisFliche 1910 in die Ordnung derLepidodendrales, ohne jedoch die genaue Familie schon bezeichnen zu können. Diese Sporophylle stehen denen anderer triadischen Lycophyten (Lycostrobus, Cylostrobus, Skilliostrobus) nahe, die auch Mikrosporen desAratrisporites Typus bilden. Die große Verbreitung dieser Sporen deutet auf eine weltweite triadische Verbreitung der Lycophyten und insbesondere eines Lepidodendren Stammes.Diese Lycophyten der Basis der „Marnes bariolées“ der elsässischen Lettenkohle sind die ersten Zeugen einer Moorflora in unmittelbarer Nähe einer Meeresküste. Sie folgt einer Küstenphase mit breiten intertidalen, karbonatablagernden Prielen, mit umgelagerten Trockenrissen, mit Stromatoliten und „birds eyes“, was ein Auftauchbereich charakterisiert.AbstractNumerous dispersed and well preserved lycopsidean reproductive organs have been discovered at Wasselonne (Bas-Rhin, France) in the middle part of the Lettenkohle. They were known under the nameAnnalepis zeilleriFliche 1910 but they passed unnoticed because of a misappreciation of their structure and of their affinities. These sporophylls, which are 2,5–4,5 cm long and 1–2 cm wide, consist of a distal triangular short limb and a proximal long winged petiole which bears adaxially a single, large and tongue-shaped sporangium. According as it is a microsporophyll or a megasporophyll, the sporangium contains small monolete microspores or large trilete megaspores which agree respectively with the dispersed microspore and megaspore generaAratrisporitesLeschik andTenellisporitesPotonie.The cones composed of these sporophylls must have been very large as they had a diameter of at least 14 cm. Among all the known Mesozoic lycopsidean cones they are by far the largest found as yet. From their general organization and their size, these sporophylls are quite similar to those of the CarboniferousLepidodendraceae of which they perhaps are one of the descendants. We therefore place the genusAnnalepisFliche 1910 in the orderLepidodendrales, without being able to state the family as yet. These sporophylls also look like those of some other Triassic Lycophytes (Lycostrobus, Cylostrobus, Skilliostrobus) which also produce microspores similar to the microspore genusAratrisporites. The large distribution of these spores shows that the Lycophytes and more precisely a lepidodendralean issue had an important world-wide development during the Triassic.This lycopsid flora found in the lower part of the “Marnes bariolées” of the Alsacian Lettenkohle is the first true wittness of the permanent settlement of a swampy terrestrial flora at the border of a marine environment. It follows a coastal episode with wide carbonaceous intertidal channels, reworked mud-cracks, stromatolithes and birds eyes, typical of the intertidal space.RésuméDe nombreuses sporophylles, bien conservées, de Lycophytes ont été trouvées à Wasselonne (Bas-Rhin, France) dans la partie moyenne de la Lettenkohle. Elles étaient connues sous le nom de genre et despèceAnnalepis zeilleriFliche 1910, mais sont passées inaperçues en raison de la méconnaissance de leur structure et, par là, de leurs affinités. Ces sporophylles, qui mesurent 2,5–4,5 cm de long et 1–2 cm de large, sont formées dun limbe triangulaire et dun large pétiole ailé sur lequel est inséré un seul grand sporange linguiforme. Selon quil sagit dune microsporophylle ou dune mégasporophylle, le sporange contient de petites microspores monolètes ou des grandes mégaspores trilètes qui correspondent aux formes dispersées connues respectivement sous les noms de genreAratrisporitesLeschik etTenellisporitesPotonié.Les cônes constitués par ces sporophylles devaient être très grands puisquils mesuraient au moins 14 cm de diamètre. De tous les cônes de Lycophytes mésozoïques connus ce sont de loin le plus grands trouvés à ce jour. Par leur structure générale et leur grande taille, les sporophylles de la Lettenkohle ressemblent à celles des Lépidodendracées carbonifères dont elles représentent peut-être un des descendants. Cest pourquoi nous classons le genreAnnalepisFliche 1910 dans lordre des Lépidodendrales, sans préciser pour le moment la famille. Ces sporophylles ressemblent aussi à celles dautres Lycophytes triasiques (Lycostrobus, Cylostrobus, Skilliostrobus) contenant également des microspores de typeAratrisporites. La connaissance de ces Lycophytes comparée à la vaste distribution, au Trias, des spores de typeAratrisporites montre limportance du développement dans le monde, à cette période, des Lycophytes et plus précisément dune lignée lépidodendralienne.Cette flore à Lycophytes récoltée à la base du niveau des «Marnes bariolées» de la Lettenkhole alsacienne est le premier témoin véritable de linstallation permanente dune flore marécageuse terrestre en bordure du milieu marin. Elle fait suite à un épisode littoral à larges chenaux carbonatés intertidaux, à fentes de dessiccation remaniées, à stromatolithes et à «birds eyes», typiques de lespace intertidal.Краткое содержаниеВ средних слоях нижне го яруса триса (уголь с большим содержанием глины) района Wasselonne (Ba-Rhin, Фран ция) установили многочисленные хорошо сохранившиес я спорофиллы Ликофит ов. Еще FLICHE в 1910 г. описал их под именем Annalepsis zeilleri, но до сих пор им he предавали большого значения из-за ошибоч ной интерпретации их структуры и родства. Эти спорофил лы (2,5–4,5 cm длины и 1–2 cm ширины) со стоят из треугольног о листка с оперенным черенком, к которому прикреплен большой языкоподобный спора нгий.В зависимости от того, идет-ли речь о микроил и макроспорофиллах, в спорангиях находят м аленькие изолирован ные микроспоры, или больш ие тройные макроспоры. Э ти споры известны под названиемКисти спорофиллов до лжны были быть значит ельной величины, т. к. их диаметр принимают за 14 см. Из всех известных д о сих пор кистей мезозойских ликофитов они являют ся наиболее большими. По их общему строению и величине эти спорофи ллы, найденные в нижни х ярусах триасе, напоминают таковые Lepidodendraceae карбона, по томками которых они м огут являться. Соответственно авто ры отнесли род Annalepis FLICHE 1910 в по рядок Lepidodendrales, не указывая при этом с емейства. Эти спорофи ллы близки другим ликофитам, обр азующим триады (Lycostrobus, Cylostrobus, Skilliostrobus), а также микроспоы тип а Aratrisporites. Широкое распрост ранение этих спор указывает н а широкое распростра нение ликофитов, образующи х триады, и в особенност и типа лепидодондров.Эти ликофиты, установ ленны у базиса „Marnes bariolés“ „эльзасского нижнего яруса триаса являются первыми ука заниями на наличие флоры торфянников в нпосре дственной близости м орского побережья. Они следую т очертаниям берегово й линии и имеют „прили “ п которых отлагаются карбонат ы, перемещенные разрыв ы усыхания, строматол иты и „птичьи глаза“ характерные для реги онов, поднявшися из во ды.

Laterally and vertically accreted tidal deposits in the Upper Proterozoic Madina-Kouta Basin, southeastern Senegal, West Africa

Abstract The association of laterally and vertically accreted tidal deposits characterizes part of the Upper Proterozoic epicontinental deposits of the West African Platform. These deposits consist of symmetric thickening-up thinning-up, decimetre- to metre-thick, units bounded by centimetre-thick argillaceous layers containing mud cracks. Each unit comprises neap—spring tidal bundles in progradational cross-bedded sandstones bounded above and below by aggradational flat-bedded sand—silt alternations. The units are interpreted as deposits resulting from migration of subaqueous dunes (lateral accretion) over mud flats (vertical accretion) in an intertidal zone. The cyclic organization of the units, although imperfect because of preservation potential of strata, cannot be explained by the dune field migration alone. A periodic variation in the tidal environment, of unknown origin but of longer duration than neap—spring cycles, is suggested.

L'événement intraviséen dans la zone moldanubienne de la chaîne varisque d'Europe: les données des formations volcano-sédimentaires dévono-dinantiennes du Massif Central Français, des Vosges du Sud (France) et de la Forêt Noire (R.F.A.)

ZusammenfassungVerschiedene Autoren vertreten die Meinung, daß das mitteleuropäische Variszikum innerhalb des Visé von einer tektonischen Phase betroffen wurde. Die gegenwärtige Arbeit soll eine genauere Vorstellung von den Ereignissen geben, welche sich um diese Zeit im nördlichen Zentralmassiv, den Vogesen und dem Schwarzwald abspielten. Innerhalb des angeführten Bereiches läßt sich nirgends eine Faltung beobachten. Es handelt sich vielmehr um ein geodynarmsches Ereignis, welches sich im obereren Visé als eine Periode der Instabilität mit sehr beachtlichen Erosionen einerseits und ebenso bedeutenden Resedimentationen andererseits äußert. Diese Zeit der Instabilität mündet noch im Laufe des obersten Visé in einer allgemeinen Heraushebung des Moldanubikums. Das Intra-Visé Ereignis ist zeitgleich mit der nordwärtigen Wanderung der synmetamorphen Deformation in den externen Zonen. Im armorikanischen Massiv fällt es anscheinend mit bedeutenden Blattverschiebungen zusammen. Offensichtlich steht hinter den Vorgängen als Ursache eine relativ plötzliche Krustenverdickung im Zusammenhang mit der variszischen Kollision. Die Heraushebung geht der paroxysmalen Deformation im späten Visé bzw. frühen Oberkarbon voraus.AbstractThe existence of an Intravisean tectonic phase in the variscan belt of Europe is admitted by some authors. The present work specifies the characteristics of such an event in the northern part of the French Massif Central, in the Vosges mountains and in the Black Forest, i.e. in the internal variscan zone. New data are given for the Vosges and the Black Forest. In the considered domain the geodynamic event does not have a folding effect. It leads to a period of instability during Late Visean, inducing important resedimentation processes as a result of erosion of the paleoreliefs. A generalized emersion of the Moldanubian Zone occurs at the same time. This event coincides with the migration toward the North of the syn-metamorphic deformation in the extern parts of the belt. In the Armorican Massif (external zone) strike slip faults are active during the same period. That event can be explained by the crustal thickening resulting from the variscan collision. The uplift preceds the paroxysmal Late Visean and Upper Carboniferous tectonic phase.ResuméLexistence dune phase tectonique intraviséenne dans la chaîne varisque dEurope a été admise par divers auteurs. Le présent travail apporte des précisions sur la nature de cet événement dans le Nord du Massif Central, les Vosges et la Forêt Noire, cest à dire dans la zone interne varisque. Des données nouvelles concernent les Vosges et la Forêt Noire. Dans le domaine étudié, cet événement géodynamique nest pas phcatif et se caractérise par une période dinstabilité au cours du Viséen supérieur qui conduit à dimportants phénomènes de resédimentation, résultats de lérosion de paléoreliefs. Cette période dinstabilité se prolonge au cours du Viséen supérieur où une emersion généralisée se produit dans la zone moldanubienne. Dans les zones externes septentrionales, la déformation synmétamorphique qui se déplace vers lextérieur de la chaîne est contemporaine de cet événement. Dans le massif armoricain (zone externe), il se traduit par des mouvements décrochants. Cet événement sexplique par un épaississement crustal, conséquence directe de la collision varisque et se traduit par un soulèvement qui précède la phase de déformation paroxysmale dâge tardi-viséen et carbonifère supérieur.Краткое содержаниеМногие авторы считаю т, что среднеевропейс кий Варисцикум подверга лся воздействию тект онических сил в визейском веке. Н астоящая работа имее т целью проверить подробно с праведливость этого утверждения и рассмотреть событи я, происходившие в наз ванный отрезок времени в сев ерном Центральном ма ссива, в Вогезах и в Шварцвал ьде. В описанном регио не никаких складкообра зований не обнаружив ают. Здесь имело место геодинам ическое событие, проя вившееся в верхнем визейском в еке, как период нестаб ильности, при котором, с одной ст ороны, протекала знач ительная эрозия, а с другой — зна чительное повторное отложение осадков. В течение вер хнего визейского век а период нестабильнос ти влился в общее подн ятие Молданубия. События в визейском п ериоде связаны с перемещением синмет аморфной деформации внешних зон к северу. В Арморик анском массиве это яв ление совпадает, по-видимом у, со значительными ст руктурными сдвигами. Сравнитель но неожиданное уплотнение пород, явн о связанное с герцинс кими коллизиями, бессомненно являетс я причиной названных событий. Поднятие пре дшевствовало парокс измальной деформации, происход ившей, вероятно, в позд них отделах визейского я руса, или раннего верх него карбона.

Une mégaséquence d'émersion: la Lettenkohle (Trias Est de la France). Mise en évidence de marées par l'imbrication bipolaire de plaques de dessiccation

ZusammenfassungSchon im mittleren Oberen Muschelkalk zeigen die vollmarinen Fazies eine allmähliche Verringerung der Meerestiefe. Mit dem Auftreten der Lettenkohle scheint die im Oberen Muschelkalk optimale Transgression langsam abzuklingen. Ein progressiver übergang von einer marinen Riffbildung zu einem Küstenlandmoor veranschaulicht eine Regression. Dieser Vorgang bildet die Megasequenz einer progressiven totalen Emersion.Gezeiteneinflüsse werden an eingeregelten Trockenriklasten und Rinnen beobachtet. Wattgefüge werden mit denen des heutigen Wattablagerungsmilieu des Mont Saint Michel in der Normandie verglichen.AbstractFrom the Middle Upper Muschelkalk the marine facies are becoming less deep. At the beginning of the Lettenkohle the marine transgression which had reached a maximum in the Upper Muschelkalk now seems to decline. Regression is evidenced by progressive replacement of reef facies by coastal deposits and supratidal marshes. The process results in the erection of the coarsening upward cycle of a progressive complete emergence.The trace of tides, i.e. bipolar desiccation clast fabric as well as tidal channels have been observed. Some tidal structures are compared with those of the depositional environment of Mont Saint Michel (Normandie).RésuméDès la partie moyenne du Muschelkalk supérieur, les faciès marins francs deviennent de moins en moins profonds. Avec lavènement de la Lettenkohle, la transgression marine à son maximum dans le Muschelkalk supérieur, semble sépuiser. Le caractère régressif est attesté par le relais de faciès récifaux, par des dépÔts littoraux et des marais cÔtiers. Cette évolution est marquée par lédification dune mégaséquence démersion complète. Des indices de marées sous forme dimbrications bipolaires de plaques de dessiccation ainsi que des chenaux tidaux ont été observés. Certaines structures tidales ont été comparées avec celles de lestran du Mont-Saint-Michel en Normandie (France).кРАткОЕ сОДЕРжАНИЕНА ОсНОВАНИИ ИсслЕДО ВАНИь ОтлОжЕНИИ сРЕД НЕгО ВЕРхНЕгО РАкУшЕЧНОг О ИжВЕстНькА УстАНОВ ИлИ пОстЕпЕННОЕ ОМЕлЕНИЕ ЁтОгО МОРск ОгО БАссЕИНА. В НИжНИх ьРУсАх тРИАсА тРАНсг РЕссИь ВЕРхНЕгО РАкУ шЕЧНОгО ИжВЕстНькА пРЕкРАЩА Етсь И НАЧИНАЕтсь ЕгО ОтстУплЕНИЕ.РЕгРЕссИУ ЁтУ МОжНО ж АМЕтИть пО УсИлИВАУЩ ИМсь пЕРЕхОДЕ От МОРскИх Р ИФОВ ДО НАДлИтОРАльН ОгО БОлОтА. пРИ ЁтОМ ОБРАж ОВАлАсь МОЩНАь сВИтА сО ВсЕ ВОжРАстА УЩИМ пОьсОМ пЕсЧАНОг АлЕЧНИкОВых МОРскИх ОтлОжЕНИИ, пО кРыВАУЩИх РАНЕЕ ОБРАжОВАВшИЕсь ОсАД ОЧНыЕ пОРОДы. ВлИьНИЕ пРИлИВОВ-Отл ИВОВ жАМЕтНО пО БОРОж ДАМ И РЕгУльРНыМ тРЕЩИНАМ УсыхАНИь. стРУктУРы, п ОьВИВшИЕсь жДЕсь, схОДНы с тАкОВы МИ сЕгОДНьшНЕгО РАИОНА В Mont Saint Michel В НОРМАНДИ И.

The prehistoric peopling of Southeast Asia

Ancient migrations in Southeast Asia The past movements and peopling of Southeast Asia have been poorly represented in ancient DNA studies (see the Perspective by Bellwood). Lipson et al. generated sequences from people inhabiting Southeast Asia from about 1700 to 4100 years ago. Screening of more than a hundred individuals from five sites yielded ancient DNA from 18 individuals. Comparisons with present-day populations suggest two waves of mixing between resident populations. The first mix was between local hunter-gatherers and incoming farmers associated with the Neolithic spreading from South China. A second event resulted in an additional pulse of genetic material from China to Southeast Asia associated with a Bronze Age migration. McColl et al. sequenced 26 ancient genomes from Southeast Asia and Japan spanning from the late Neolithic to the Iron Age. They found that present-day populations are the result of mixing among four ancient populations, including multiple waves of genetic material from more northern East Asian populations. Science, this issue p. 92, p. 88; see also p. 31 Ancient genomes reveal four layers of human migration into Southeast Asia. The human occupation history of Southeast Asia (SEA) remains heavily debated. Current evidence suggests that SEA was occupied by Hòabìnhian hunter-gatherers until ~4000 years ago, when farming economies developed and expanded, restricting foraging groups to remote habitats. Some argue that agricultural development was indigenous; others favor the “two-layer” hypothesis that posits a southward expansion of farmers giving rise to present-day Southeast Asian genetic diversity. By sequencing 26 ancient human genomes (25 from SEA, 1 Japanese Jōmon), we show that neither interpretation fits the complexity of Southeast Asian history: Both Hòabìnhian hunter-gatherers and East Asian farmers contributed to current Southeast Asian diversity, with further migrations affecting island SEA and Vietnam. Our results help resolve one of the long-standing controversies in Southeast Asian prehistory.

Modern human fossils from Tam Pa Ling, Laos

Supplement: Program of the 81st Annual Meeting of the American Association of Physical Anthropologists (2012)The catacomb of Saints Peter and Marcellinus located in the south-east of Rome approximately contains 25 000 graves dated from the 3rd to the 5th century AD. Seven newly discovered rooms having an unusual organization in the heart of the catacomb were investigated in 2003. Excavations of these rooms revealed a mass grave, where 3000 corpses were laid together. These individuals were stacked in rows apparently following a common fatal incident. Presumably, this epidemic crisis occurred between the 1st and the 3rd century AD. The specific funerary treatment (textile wrapping and plaster) recalls mummification and might be related to exogenous practices, possibly connected to Early Christians. Moreover, the presence of rare and expensive materials (e.g., Baltic amber, resins and gold threads) may indicate a high social status. Stable isotope analyses (carbon, nitrogen and oxygen) of bone collagen, bone apatite and tooth hydroxyapatite were carried out on 111 individuals to obtain further information on their diet and residential mobility. Additionally, a study of dental nonmetric traits was conducted on 200 individuals to define the biological distance between the deceased and to assess their phenetic similarity. The combination of these two approaches will bring new insight into the homogeneity of the Early population of the catacomb of Saints Peter and Marcellinus and the relationship between funerary practices and geographical origin of buried individuals.

Les écosystèmes microbiens marqueurs des variations des niveaux lacustres en contexte de fan-deltas. Exemple du rift rhénan méridional (Europe occidentale)

The Rhine Graben begins to develop in the Upper Eocene. During the first paroxysmal stage a belt of sandstones and conglomerates, the so-called “Conglomé-rats cotiers”, is deposited on the rift border. In the graben an euryhaline lacustrine basin regulates the extension of fan-deltas which are developing along the boundary faults of the rift.Stromatolites preferentially colonize the littoral fringe of the lake where they find indurated substratums. So they appear to be excellent markers of the transgressive movements of the lake and its palaeomargins. The stromatolites also allow an excellent sequential subdivision to reconstruct the history of the basin.

Characterizing the physical properties of rocks from the Paleozoic to Permo-Triassic transition in the Upper Rhine Graben

Geothermal energy exploitation in the Upper Rhine Graben currently targets high-temperature anomalies in the crystalline Paleozoic basement at depths up to 5xa0km. However, at certain locations (e.g. Rittershoffen, France), geothermal installations are actively targeting resources at shallower depths where the Paleozoic granite transitions into the overlying Permo-Triassic sandstones. We here investigate the variation in physical properties—including porosity, P-wave velocity, permeability, uniaxial compressive strength, and thermal properties—in rocks that locally extend across the Paleozoic–Permo-Triassic boundary in four locations to the west of the Upper Rhine Graben. The lithologies investigated include sandstones, breccia, granites, metagranites, dolomite, and altered and unaltered volcanic rocks and represent the variety of lithologies at this transition. We note that while the porosity, permeability, thermal conductivity, and P-wave velocity of the Permo-Triassic sedimentary cover and Paleozoic crystalline basement rocks are consistent with values determined for rocks from exploratory and production boreholes at Soultz-sous-Forêts (France), the other lithologies (belonging to neither the sedimentary nor basement sequences) are conspicuously lower in porosity and permeability. Further, the attendant strength of these other lithologies could make them relatively unamenable to fracturing, reducing the possibility of fracture-controlled permeability in these units. Indeed, we conclude that in areas where these low-permeability and high-strength rocks act to cap the crystalline basement, hydrothermal convection may be curtailed and geothermal exploitation may be rendered untenable.