Literatura académica sobre el tema "Roches dures"

Les pieux forés et cimentés sont une solution envisagée comme fondations de structures marines dans les roches tendres à dures rencontrées au large des côtes françaises. Le dimensionnement des pieux au rocher est un exercice délicat. L’exécution de séries d’essais de cisaillement d’interface à rigidité constante (dits essais CNS) est considérée comme une approche réaliste pour estimer la résistance au cisaillement de l’interface roche-ciment sous chargements statiques et cycliques. Les essais CNS sont conditionnés par deux paramètres clés qui sont liés aux caractéristiques du massif rocheux : la rigidité du massif et la géométrie de l’interface roche-ciment. Cet article propose une approche méthodologique pour estimer ces paramètres.

Le principe de l'isolement des déchets radioactifs dans une formation géologique est simple. L'eau étant le principal vecteur de la migration des ions, il suffit de placer les radionucléides en profondeur au sein d'un milieu tres peu perméable, dans une région ou le gradient hydraulique est tres petit - ce qui signifie, en général, sous une plaine - pour faire en sorte que les nucléides ne puissent s'échapper et rejoindre la biosphere qu'après un temps suffisamment long pour qu'ils aient perdu l'essentiel de leur activité, ce qui peut prendre 100 000 ou 1000000 d'années. II faut ensuite que le milieu géologique garde son intégrité pendant toute cette durée; son ancienneté est évidemment garante de son avenir, mais il faut que les mouvements tectoniques, l'érosion, le climat ne viennent pas altérer son existence ni affecter ses structures. Avant ce long terme pour les déchets de haute activité, l'épisode thermique, avec les dilatations puis les contractions qu'il impose, est susceptible de bousculer les formations géologiques, et les effets thermomécaniques doivent être examinés avec soin pour chaque milieu hôte envisagé, avec une estimation de leurs propriétés rhéologiques à long terme et à tres long terme, ce qui est assez inhabituel en Mécanique des Roches. Le cas des milieux plastiques (sei, argile) et celui des milieux cassants (granite, schiste) posent des problemes différents et doivent être analysés indépendamment.

Un territoire, en surface, est déterminé par sa composition et sa structure : la Pévèle rassemble des roches tendres (argiles, sables) au cœur d’une synforme largement ouverte, esquissée par les niveaux crayeux du Crétacé supérieur, discordants sur un socle paléozoïque, structuré par l’orogenèse varisque. L’observation d’églises de plusieurs villages conduit à s’interroger sur la provenance des pierres dures qui ont été nécessaires, et sur leurs conditions d’acheminement il y a environ 1 000 ans.

Depuis les années 1970, l’étude des collections lithiques préhistoriques a vécu en France une profonde modernisation. André Leroi-Gourhan, d’abord intéressé par les techniques traditionnelles, prit pour objectif d’appréhender les activités techniques menées dans un site par un groupe préhistorique, dans une perspective ainsi dénommée « palethnologique ». Il a aussi promu la notion de chaîne opératoire introduite auparavant par Marcel Mauss. Mais ce sont les expérimentateurs de la taille des roches dures, F. Bordes et J. Tixier, qui vont permettre d’enrichir cette notion de ses applications concrètes. J. Tixier, surtout, stabilise la terminologie de la pierre taillée, et systématise la « lecture technologique » qui permet de reconstituer mentalement le déroulement du façonnage d’un outil ou du débitage d’un nucléus. Il introduit aussi une distinction fondamentale entre « méthode » (la démarche -l’agencement des enlèvements successifs- suivie pour atteindre le but de la chaîne opératoire : un type ou une classe de produits) et « technique(s) » (qui réfère aux modalités pratiques d’exécution des enlèvements). Sur cette base, dès 1980, Tixier et collègues introduisent les notions d’économie des matières premières, du débitage et de l’outillage, corollaires de la notion de règles de gestion. La notion d’intention -entre débitage, supports et (certains) outils- apparaît également, fondant le postulat selon lequel les modalités de la taille sont cohérentes avec la morphologie des produits recherchés. C’est ce postulat que suit la démarche française en technologie lithique : percevoir -comprendre- les intentions de la production lithique, avant de classer et de mesurer. Cette démarche est ensuite appliquée à la collection lithique de Yokomichi (Dept de Yamagata, NE de Honshu), à débitage laminaire mais antérieure à la production de lamelles, ainsi datable d’environ 18 000 BP. On perçoit d’abord qu’y coexistent deux débitages laminaires : l’un de lames légères et rectilignes à petit talon, tirées de nucléus étroits, et l’autre de fortes lames à talons épais débitées de nucléus plus larges. Parmi les outils retouchés, ce sont les quelques « couteaux de Sugikubo » (des pointes à dos élancées de profil rectiligne) dont les supports correspondent à l’intention première du débitage étroit, quelques autres outils étant réalisés sur des supports de second choix. Un tel couteau de Sugikubo, dans une collection similaire, présente une fracture à longue languette inverse qui suggère fortement qu’il s’agit en fait, au moins pour partie, de pointes de projectile. Le débitage large, lui, avait pour intention première l’obtention de grandes lames pointues, très difficiles à réaliser, tandis que ses nombreux produits de second choix et d’aménagement restent bruts (utilisables comme couteaux) ou se retrouvent dans les « burins de Kamiyama » (en fait, de très probables couteaux ravivés comme les couteaux de Kostienki). Une expérimentation montre que les deux débitages sont réalisés par percussion directe à la pierre tendre, mais selon des modalités distinctes : par percussion tangentielle pour les lames légères à petit talon, par percussion en retrait pour les lames plus fortes à gros talon.

Aspectos geológico-geotécnicos devem ser levados em consideração desde os estudos de exploração geológica, em empreendimentos mineiros. Alguns acidentes ocorridos em minas, nas últimas décadas, poderiam ser evitados, caso as condições geológico-geotécnicas do maciço fossem compreendidas. Ainda existe grande dificuldade em se classificar alguns tipos de rochas, sobretudo as rochas consideradas brandas, por meio dos sistemas de classificação geomecânica conhecidos. A grande maioria das classificações existentes foram desenvolvidos baseadas em características de rochas duras. Para maciços rochosos pouco resistentes, é necessário adaptar os sistemas atuais ou desenvolver novos sistemas de classificação, que sejam específicos para maciços rochosos brandos praticamente contínuos. O objetivo deste artigo é propor a utilização de técnicas de Aprendizagem de Máquina para previsão de parâmetros geotécnicos de rochas brandas, especialmente filito. Foram utilizados dados históricos de resultados de ensaios geotécnicos de laboratório de rochas de minas do Quadrilátero Ferrífero, que, por meio da interação otimizada, e com auxílio de técnica de Inteligência Artificial, como a Rede Neural Artificial e Regressão Linear, sejam capazes de gerar resultados de interesse para análises de estabilidade e modelagens geotécnicas. Das técnicas utilizadas, resultados mostraram que o método de Regressão Linear se mostrou satisfatório na determinação de parâmetros de resistência de filitos brandos e com boas perspectivas de ampliação e utilização para outros parâmetros, assim como outros tipos de rochas.

No processo de infiltração para a fabricação de ferramentas de perfuração de rocha (coroa), analisaram-se três procedimentos com utilização de três pós de matrix: dois à base de carbonetos de tungstênio e um à base de tungstênio, pelos quais se investigaram os efeitos de suas características, os da microestrutura e a dureza de um cermet. As amostras na forma de coroa foram preparadas pela técnica da infiltração, em que o pó matrix, compactado em um molde de grafita, montado com um tubo (carcaça) de aço, foi infiltrado por uma liga de cobre para consolidar o metal duro e ligá-lo à carcaça de aço. Os pós e/ou as seções dos metais duros foram caracterizados por meio de análise química, difração de Raios X, análise granulométrica, densidade, microscopia óptica e eletrônica de varredura, espectroscopia por dispersão de energia e análise térmica diferencial. Além das fases predominantes de carboneto de tungstênio e/ou tungstênio, os pós apresentaram uma pequena fração de partículas de liga metálica. Complementando o estudo iniciado em artigo já publicado, os resultados da análise microestrutural dos metais duros foram correlacionados com as características químicas, de fases, granulométricas, morfológicas e de compressibilidade dos pós investigados. Determinaram-se as micro e macrodurezas dos metais duros, e realizou-se a análise microestrutural da região da interface entre os metais duros e a carcaça de aço e também a diferença de temperatura no processo de infiltração em cada pó de matrix.

No processo de infiltração para a fabricação de ferramentas de perfuração de rocha (coroa), analisaram-se três procedimentos com utilização de três pós de matrix: dois à base de carbonetos de tungstênio e um à base de tungstênio, pelos quais se investigaram os efeitos de suas características, os da microestrutura e a dureza de um cermet. As amostras na forma de coroa foram preparadas pela técnica da infiltração, em que o pó matrix, compactado em um molde de grafita, montado com um tubo (carcaça) de aço, foi infiltrado por uma liga de cobre para consolidar o metal duro e ligá-lo à carcaça de aço. Os pós e/ou as seções dos metais duros foram caracterizados por meio de análise química, difração de Raios X, análise granulométrica, densidade, microscopia óptica e eletrônica de varredura, espectroscopia por dispersão de energia e análise térmica diferencial. Além das fases predominantes de carboneto de tungstênio e/ou tungstênio, os pós apresentaram uma pequena fração de partículas de liga metálica. Complementando o estudo iniciado em artigo já publicado, os resultados da análise microestrutural dos metais duros foram correlacionados com as características químicas, de fases, granulométricas, morfológicas e de compressibilidade dos pós investigados. Determinaram-se as micro e macrodurezas dos metais duros, e realizou-se a análise microestrutural da região da interface entre os metais duros e a carcaça de aço e também a diferença de temperatura no processo de infiltração em cada pó de matrix.

Le choix optimal des paramètres opératoires dans le découpage de blocs en roches dures avec des jets d'eau à haute pression nécessite de développer un modèle de découpage d'une saignée isolée pour ensuite l'intégrer dans un modèle de calcul du rendement de découpage d'un sillon profond tenant compte de l'interaction entre les différents jets unitaires de la tête. Un programme expérimental a été mis au point afin de valider d'une façon indépendante les hypothèses principales nécessaires pour développer les modèles. Ces bases théoriques ont rendu possible la comparaison des caractéristiques et des performances de découpage dans le granite des trois types de têtes de coupe : fixe, rotative et oscillante
The choice ot the optimal set of operational parameters for hard rock water jet cutting requires to develop a single slot cutting model and evaluate the deep-kerf cutting rate by integrating the action of the different single slots and there interactions. A special experimental program was defined to provide an independant validation of the basic hypothesis forming the single slot model and the definition of lows of the interaction between the neighbour slots. These theoretical basis allow a comparison of the performances of different types of cutting heads : fixed, rotating and oscillation in the deep-kerf cutting in granite

Le forage percussif est une technologie qui consiste à appliquer une série d’impacts dynamiques conduisant à la fragmentation de la roche par deux mécanismes principaux : l’écrasement et l’écaillage. Ces mécanismes sont fortement influencés par de nombreux facteurs qui ont fait l’objet d’investigations expérimentales et numériques pendant cette thèse. Un dispositif expérimental a été développé pour réaliser des essais d’impacts dynamiques. Un système de mesure précis a été également mis au point afin d’avoir les résultats des nombreuses séries d’essais qui ont été menées dans le cadre de cette thèse. Quant au volet numérique, un laboratoire virtuel a été construit en se basant sur un modèle rhéologique élasto-viscoplatique validé sur des essais de laboratoire pour décrire le comportement du granite et un mécanisme de contact pour simuler l’interaction insert-roche pendant un impact dynamique. Dans un premier temps, plusieurs études paramétriques ont été réalisées sur un matériau homogène. Dans un deuxième temps, une nouvelle approche de modélisation de l’hétérogénéité a été développée pour décrire la distribution des minéraux dans le granite.Ces études ont fournis des éléments primordiaux pour la compréhension des mécanisme physiques de destruction des roches dures en percussion, pour l’évaluation des effets des principaux paramètres et facteurs de forage et pour l’optimisation de l’outil de forage
Percussive drilling is a technology that consists in applying a series of dynamic impacts leading to the rock fragmentation by two main mechanisms: crushing and chipping. These mechanisms are highly influenced by many factors on which experimental and numerical investigations were carried out in this thesis. An experimental set up was developed to carry out dynamic impact tests. Several series of tests were realized and their results were measured using a precise measurement system which was also developed during the thesis. As for the numerical work, a virtual laboratory was built based on an elasto-viscoplastic constitutive model validated on laboratory tests to describe the granite behavior and a contact mechanism to simulate the insert-rock interaction during a dynamic impact. First, several parametric studies were carried out on a homogeneous material. Secondly, a new heterogeneity modeling approach was developed to describe the distribution of minerals in the granite. These studies have provided essential elements for understanding the physical mechanisms of hard rocks destruction in percussion, for evaluating the effects of the main drilling parameters and factors and for optimizing the drilling tool

L'optimisation des machines a attaque ponctuelle passe par une modelisation des tetes de creusement qui tiennent compte de leurs particularites et, notamment, du travail des pics inclines. Elle necessite une experimentation en echelle reduite specifique et s'appuie sur une modelisation analytique qui justifie le recours a un logiciel de calculs et de simulation, p. C. Map. Il permet de determiner le type de pic, la geometrie de la tete et le schema de coupe qui, dans des conditions donnees, minimisent les efforts et reduisent les vibrations. La conception de machines, equilibrees en terme de' poussees et de puissance, capables de travailler efficacement dans les roches agressives, et de machines compactes apparait alors possible

Les processus de localisation de la déformation sont la clé du comportement mécanique des roches et des sols car ils sont, par exemple, souvent précurseurs de la rupture des matériaux. Par conséquent, la compréhension des processus qui conduisent à la localisation de la déformation, et donc à la rupture, dans les géomatériaux est essentielle pour la réussite d'un grand nombre de projets d'ingénierie géotechnique. Ce travail est centré sur l’étude des sols durs, roches tendres et matériaux granulaires cimentés. Dans ce cas, la localisation de la déformation est souvent associée à des phénomènes de fracturation à différentes échelles. Les macrofractures sont généralement entourées de méso et micro fractures et leur propagation est précédée d’une zone de processus; la microfissuration, qui caractérise cette zone, peut être identifiée comme endommagement car cela affecte les propriétés mécaniques du matériau. Les bandes de cisaillement ou de compaction sont souvent associées à des microfissures et elles peuvent également être considérées comme de la localisation d’endommagement. Dans le cadre de la mécanique des roches, l’endommagement peut être causé par des phénomènes de détachement (rupture du ciment) et écrasement des grains. Pour étudier les phénomènes de localisation de la déformation et de l'endommagement, une sorte de mesure de champ non destructive doit être mis en place. Des techniques bien connues dans la géomécanique comprennent la tomographie par rayons X pour étudier la structure des matériels, et la corrélation d'image numérique (DIC) des images 2D ou 3D (volumes), pour étudier le champ de déformation. La DIC est un outil très puissant pour l’étude des phénomènes hétérogènes mais fournit uniquement des données sur la cinématique. Dans cette thèse, nous suggérons l’utilisation d’un autre outil, la tomographie ultrasonore, qui permet la mesure du champ de la vitesse ultrasonique dans un échantillon, ainsi que ses propriétés élastiques, en exploitant la théorie de la propagation des ondes. La tomographie ultrasonore, utilisée comme technique complémentaire de la DIC et d'autres mesures de champ, peut donc fournir de nouvelles informations pour comprendre les processus de déformation. Dans la mécanique des sols et des roches des méthodes acoustiques et ultrasoniques ont été largement utilisées pour mesurer les propriétés élastiques, y compris pendant les essais mécaniques. Cependant, ces mesures ont été limitées à un petit nombre limitant ainsi l'étude des hétérogénéités. La tomographie ultrasonore peut surmonter cette limitation en fournissant une carte des propriétés élastiques. La principale contribution de ce travail est le développement de la tomographie ultrasonore comme technique de mesure de champ pour tester les géomatériaux et son application dans une vaste campagne expérimentale. Des tests ont été effectués sur différents matériaux et dans différentes conditions, y compris pendant le chargement et la tomographie ultrasonore a été comparée avec les résultats obtenus par DIC ainsi que par tomographie à rayons X. Une comparaison entre DIC et tomographie ultrasonore indique que la vitesse de propagation subit des modifications importantes à un niveau de chargement pour lequel la DIC ne présente aucune déformation notable. Puisque la tomographie ultrasonore est sensible aux variations des propriétés élastiques, à savoir l’endommagement, il peut être conclu que le niveau de déformation nécessaire pour causer de l’endommagement dans ce matériau est inférieur à la résolution de la DIC. De plus, la tomographie ultrasonore semble être capable de détecter la zone de processus qui précède la fracture, et donc d’indiquer sa direction de propagation. Les différentes techniques utilisées dans ce travail fournissent des informations différentes et complémentaires. Grâce à leur combinaison, une meilleure compréhension du comportement mécanique des géomatériaux peut être acquise
The processes of strain localisation are key to the deformation behaviour of rocks and soils, because, for example, localised deformation is often precursor to material failure. Therefore the understanding of the processes leading to localised deformation, and thus to failure, in geomaterials is critical to the success of many geotechnical engineering projects. This work is focused on the analysis of localised deformation in hard soils, soft rocks and, more generally, cemented granular materials. For such materials localized deformation, in the form of localized strain, i.e., shear and compaction bands, is often associated with damage, i.e., inter and intra-granular fractures and cracks, de–bonding and breakage of particles (grain crushing). Furthermore, macrofractures are commonly surrounded by meso and micro cracks and a process zone of microfracturing precedes their propagation. To study localised phenomena such as strain and damage localisation, some kind of non-destructive, full–field measurement has to be used. Well-known techniques in geomechanics include X-ray tomography, to study material structure, and Digital Image Correlation (DIC) of 2D or 3D (volume) images, to study material kinematics and strain fields. DIC has proven to be a very powerful tool in the study of heterogeneous phenomena, but provides only data on kinematics and strain and not on associated property changes (e.g., elastic properties). In this thesis another tool, ultrasonic tomography, is suggested as a full-field measurement of the elastic property variations in test specimens through mapping of ultrasonic wave propagation velocities. Ultrasonic tomography, as complementary technique to DIC and other full-filed measures, can thus provide new insight into the deformation processes. In rock and soil mechanics, acoustic and ultrasonic methods have long been used to measure the elastic properties of test materials, including during mechanical testing. However, such measures have generally been limited to only a few measurement paths (usually just one) for a whole sample, thus restricting the study of heterogeneity. Ultrasonic tomography can overcome this limitation to provide a full-field measure. The main contributions of this work are the development of ultrasonic tomography analysis for laboratory geomechanics (both in terms of the experimental method and subsequent data analysis) and its application to analyse material deformation and, in particular, material evolution during loading (time-lapse ultrasonic tomography). The developed ultrasonic tomography approach has been applied to investigate geomaterial behaviour in laboratory tests. In this context, experimental campaigns have been carried out on different materials, where the ultrasonic tomography has been complemented by comparisons with displacement and strain fields from 2D and 3D DIC plus structural analysis by X-ray tomography. A comparison between DIC and ultrasonic tomography results reveals that the latter shows important changes inside the sample in a stage of loading where the DIC may not. As ultrasonic tomography is sensitive to damage, it can be concluded that the degree of deformation needed to cause detectable damage is below the resolution of the DIC. Moreover, the ultrasonic tomography seems to be able to detect the damaged zone surrounding fracture tips and thus can indicate where the fractures will propagate. However, when deformation becomes too high or fractures propagate, ultrasonic signals cannot be acquired, so ultrasonic tomography is not possible; in such situations DIC can still provide important information on the deformation mechanisms. The different full-field techniques employed in this work have thus been found to provide different and complementary information. Furthermore, it is shown that better understanding of the mechanical behaviour of geomaterials can be gained through the combination of more than one technique

Groundwater is considered the major portion of the world´s freshwater resources. Groundwater in Angola is utilised for several urban centres on the coast and in the arid southern provinces and is a major source for rural supply. The main objective of the present work was to process and analyse optical and radar images that cover the study area and combine them in a GIS to identify groundwater patterns in fractured hard rock aquifers and sedimentary basins in the valleys. Field observations and the geological data allowed to distinguish two main aquifer types in the study are: one detritic and other fractured that is the object of this study. The results from the study show that, integration and interpretation of different thematic layers such as lineament, drainage, vegetation index and on field data is useful to predict the recharge and discharge areas. Concerning to water quality, hydrogeochemistry analysis shows that, to the physical-chemical parameters analysed, groundwater in the study area can be evaluated as good quality water; Identificação de padrões de água subterrânea com base em detecção remota. Estudo de caso: aquíferos em rochas duras fracturadas no Wako Kungo, Angola Resumo: A água subterrânea é considerada a maior porção dos recursos de água doce do mundo. A água subterrânea é utilizada em vários centros urbanos das províncias do litoral de Angola e nas províncias áridas do Sul é uma das principais fontes de abastecimento nas zonas rurais. O presente trabalho tem como objetivo principal processar e analisar imagens ópticas e de radar que cobrem a área de estudo e combiná-las em um SIG para identificar padrões de águas subterrâneas em aquíferos fracturados e bacias sedimentares nos vales. As observações de campo e os dados geológicos permitiram distinguir dois principais tipos de aquíferos na área de estudo, um de tipo detrítico e outro fracturado, que é o objecto deste estudo. Os resultados mostram que a integração e interpretação de diferentes camadas temáticas tais como lineamentos, drenagem, índice de vegetação e dados de campo, é útil para prever áreas de recarga e descarga. No que diz respeito à qualidade da água, o estudo hidrogeoquímico mostrou que para os parâmetros físico-químicos analisados, as águas subterrâneas da área de estudo podem ser avaliadas como águas de boa qualidade.

This was an applied ethnographic study of natural and cultural resources of contemporary significance for American Ojibway' tribes and Canadian Ojibway First Nations that are or were once present within or in the immediate vicinity of four National Park Service (NPS) units in the Midwest Region: Sleeping Bear Dunes National Lakeshore (SLBE), Michigan; Pictured Rocks National Lakeshore (PIRO), Michigan; Apostle Islands National Lakeshore (APIS), Wisconsin; and Voyageurs National Park (VOYA), Minnesota. The main objective of this study, according to the Scope of Work (SOW) of 1996, was to develop a documented basis of knowledge regarding historic and current use of resources by culturally affiliated Native American tribes that should help park managers anticipate Native American resource use issues that may confront them in the future and thus be better prepared to deal with them in an informed and culturally sensitive manner. The study also was to provide recommendations regarding preservation, monitoring, mitigation, interpretation, and use access issues. The research was designed to provide a historical and ethnographic overview and assessment of Native American, Southwestern Ojibway in particular, land and resource use as it pertains to the region where the parks are located, and to each park unit. This study also provided an inventory of ethnographic resources known to have been significant for culturally affiliated Southwestern Ojibway tribes at different points in time.

L'etude des formations sableuses aux embouchures des oueds tensift, ksob et souss de l'atlas-atlantique (maroc) permet de mettre en evidence les processus de leur mise en place, ainsi que l'origine de leur materiel. Les oueds apportent jusqu'a l'ocean des elements terrigenes (quartz, feldspaths et mineraux lourds). Ces elements sont remanies et melanges aux depots marins. Le stock sedimentaire est redistribue par les actions marines, et principalement une forte derive littorale nord-sud. Ainsi, dans le systeme du tensift, le materiel dunaire evolue sous l'influence des alizes et des vents d'ouest, mais l'activite de ces derniers se revele plus efficace. Dans le systeme de ksob, le materiel dunaire evolue sous l'action principale des alizes. Dans le systeme du souss, la dynamique eolienne se fait sous l'action conjuguee des alizes et des vents d'ouest. Ces evolutions sedimentaires se traduisent par une amelioration du tri, une diminution progressive du grain moyen et des teneurs en carbonates et mineraux lourds, ainsi que par une eolisation croissante des grains quartz.

Le lithium fait partie de ces éléments fondamentaux pour la réalisation de la transition environnementale. Métal aux propriété multiples, il est exploité principalement dans les salars, bientôt peut-être dans les roches dures telles que les pegmatites. Gloaguen et al. passent en revue les systèmes et conditions géologiques susceptibles d’engendrer des concentrations lithinifères significatives.

Geomorphology is the study of form and structure of sand dunes. Dunes are found in three types of landscapes: sea coasts and lakeshores, river valleys, and arid regions. Coastal dunes are formed along coasts in areas above the high water mark of sandy beaches. They occur in both the northern and southern hemi sphere from the Arctic and Antarctic to the equator, and in arid and semi-arid regions. They are very common in temperate climates but are less frequent in tropical and subtropical coasts. Dunes are also common around river mouths where the sand carried in water is deposited (Carter et al. 1990b). During floods rivers overflow their banks and deposit sand in river valleys that is subsequently dried by wind and shaped into dunes. In dry regions with less than 200 mm of precipitation per year, the weathering of sandstone and other rocks produce sand that is subject to mass movement by wind because of sparsity of vegetation. There are many similarities in processes and patterns of dune form and structure among these three systems, however each location has its own unique features. In this chapter the emphasis will be on the geomorphology of dune systems along the coasts of oceans and lakes. Coastal geomorphologists have been attempting to classify the coastal land forms but they defy a simple classification because of tremendous variability in plant taxa, sand texture, wind velocity, climate, sand supply, coastal wave energy and biotic influences including human impact. According to Carter et al. (1990b) the great variety of coastal land forms around the world is primarily related to sediment availability, climate, wave energy, wind regime and types of vegetation. Classification based on these criteria would be more useful in distinguishing between shoreline dune forms than the use of subjective terms—for example white, grey or yellow dunes—sometimes employed by plant ecologists (Tansley 1953). Cowles (1899) said ´a dune complex is a restless maze´ because the great topographic diversity depends on changes in the dune terrain from day to day, month to month, season to season and year to year.

The chapter explores Colson’s sources of income under the Old Regime and how this was related to his position in society. Although he drew revenues from familial property he owned in Varennes and a variety of other investments, his main sources of income came from his position as legal advisor and financial administrator to the Ravary wine-making family and, above all, to the Longaunay family of nobles. The chapter focuses, in particular, on the complex relations linking him to the Marquise, Marquis, and Comte of Longaunay in his role of overseeing the exploitation of the family’s lands and seigniorial dues in Normandy and Berry and serving as point man in the many lawsuits in which the family found itself entangled. It also examines the wide variety of his other responsibilities for this family beyond finances, and his close relations with Roch Lemaigre, the local intendant living near the family’s possessions in Berry in the small town of Levroux.

The South Sumatra Basin is renowned as a prolific hydrocarbon area since the early era of oil. Resource discovery has declined since the early 21st century. The Talang Akar Formation (TAF) has been massively explored to seek new potential resources. There is an opportunity to look into more detail on the low contrast low resistivity (LCLR) part, which is included as the upper part of TAF. This study will provide an analogue model of the flow unit from outcropped TAF rocks in Air Batu regency. Field observations include outcrop modeling to capture sedimentation patterns, sampling on selected layers for petrographic purposes, facies characterization, geometry measurements from channel deposits, and flow unit modeling. We observed five facies’ associations, which are: transverse bar (Sp); overbank deposit (Fm); dunes (St); planar bed flow (Sh); ripples (Sr); and debris flow deposit (Gms). Petrographic analysis revealed that the samples have a laminar and dispersed shale distribution. The LCLR reservoir detects and controls porosity and pore size ranging from poor to excellent, as well as grain contact. The difference in the facies is any kind of porosity. The facies of transverse bar, dunes, and ripples show very good to excellent porosity with low shale content and are characterized as high-flow units. Yet, the other facies show medium percentage porosity but the interconnection between pores is poor to good, and these have medium to low-flow units.

Mojave National Preserve (MOJA) in the Mojave Desert of southern California hosts an extensive geologic record, with units ranging in age from the Paleoproterozoic (2.5 to 1.7 billion years ago) to the Quaternary (present day). MOJA topography is dominated by numerous mountain ranges hosting extensive geological exposures divided by expansive valleys, dunes, and a low elevation dry salt lake. Some geological units are fossil-bearing, both within the preserve and in adjacent lands outside the boundaries of the preserve. The fossils preserved within MOJA span from the Proterozoic Eon (uncertain maximum age of fossiliferous rocks, but at least approximately 550 million years ago) to the Holocene Epoch (beginning 11,700 years ago). Abundant and diverse marine fossils are preserved in units dated from the late Proterozoic through most of the Cambrian, as well as from the Devonian through the early Permian. More recent volcanic tuff and unconsolidated sedimentary deposits in valleys preserve Cenozoic flora and fauna. Geologic surveys documented paleontological resources within the modern (2023) boundaries of MOJA as early as 1914, but fossils were rarely the focus of detailed study, and no comprehensive inventory was compiled. John Hazzard was the first geologist to devote significant attention to the study of paleontology within MOJA. Throughout the 1930s and 1940s, Hazzard and collaborators identified Paleozoic assemblages within the Kelso and Providence Mountains. Between the 1950s to 1980s, several dissertations and theses described the geology of various areas within MOJA, in which the authors provided limited paleontological descriptions and fossil locality information. Jack Mount conducted extensive paleontological research in the Cambrian sections of the Providence Mountains in the 1970s and 1980s, focusing on olenellid trilobites in the Latham Shale. As early as the 1960s, rockhounds collecting opalite and petrified wood discovered fossilized plant material and vertebrate bones in areas now in south-central MOJA and notified paleontologists at San Bernardino County Museum (SBCM). This resulted in one of the only paleontological excavations in what is now MOJA, with collections of Miocene vertebrate fauna including camelid and early rhino material. More recently, James Hagadorn reported the late-surviving Ediacaran organism Swartpuntia in an assemblage from the Wood Canyon Formation of the Kelso Mountains in 2000. From October 2021 to January 2022, a field inventory was conducted to determine the scope and distribution (both temporal and geospatial) of paleontological resources at MOJA. An additional week of field work was conducted in December 2022. A total of thirteen localities were documented and field-checked throughout the preserve. These localities resulted from field checks of previously reported fossil sites, as well as new discoveries based on literature searches and information provided by MOJA staff. The findings of this report constitute a baseline of paleontology resource data for MOJA, and reflect the current understanding of the scope, significance, and distribution of MOJA’s fossil record. This report provides a foundation for the management and protection of paleontological resources within MOJA and supports future education, interpretation,

Mojave National Preserve (MOJA) in the Mojave Desert of southern California hosts an extensive geologic record, with units ranging in age from the Paleoproterozoic (2.5 to 1.7 billion years ago) to the Quaternary (present day). MOJA topography is dominated by numerous mountain ranges hosting extensive geological exposures divided by expansive valleys, dunes, and a low elevation dry salt lake. Some geological units are fossil-bearing, both within the preserve and in adjacent lands outside the boundaries of the preserve. The fossils preserved within MOJA span from the Proterozoic Eon (uncertain maximum age of fossiliferous rocks, but at least approximately 550 million years ago) to the Holocene Epoch (beginning 11,700 years ago). Abundant and diverse marine fossils are preserved in units dated from the late Proterozoic through most of the Cambrian, as well as from the Devonian through the early Permian. More recent volcanic tuff and unconsolidated sedimentary deposits in valleys preserve Cenozoic flora and fauna. Geologic surveys documented paleontological resources within the modern (2023) boundaries of MOJA as early as 1914, but fossils were rarely the focus of detailed study, and no comprehensive inventory was compiled. John Hazzard was the first geologist to devote significant attention to the study of paleontology within MOJA. Throughout the 1930s and 1940s, Hazzard and collaborators identified Paleozoic assemblages within the Kelso and Providence Mountains. Between the 1950s to 1980s, several dissertations and theses described the geology of various areas within MOJA, in which the authors provided limited paleontological descriptions and fossil locality information. Jack Mount conducted extensive paleontological research in the Cambrian sections of the Providence Mountains in the 1970s and 1980s, focusing on olenellid trilobites in the Latham Shale. As early as the 1960s, rockhounds collecting opalite and petrified wood at Hackberry Wash discovered fossilized plant material and vertebrate bones and notified paleontologists at San Bernardino County Museum (SBCM). This resulted in one of the only paleontological excavations in what is now MOJA, with collections of Miocene vertebrate fauna including camelid and early rhino material. More recently, James Hagadorn reported the late-surviving Ediacaran organism Swartpuntia in an assemblage from the Wood Canyon Formation of the Kelso Mountains in 2000. From October 2021 to January 2022, a field inventory was conducted to determine the scope and distribution (both temporal and geospatial) of paleontological resources at MOJA. An additional week of field work was conducted in December 2022. A total of thirteen localities were documented and field-checked throughout the preserve. These localities resulted from field checks of previously reported fossil sites, as well as new discoveries based on literature searches and information provided by MOJA staff. The findings of this report constitute a baseline of paleontology resource data for MOJA, and reflect the current understanding of the scope, significance, and distribution of MOJA’s fossil record. This report provides a foundation for the management and protection of paleontological resources within MOJA and supports future education, interpretation, and research.