scholarly journals New data on settlement and environment at the Pleistocene/Holocene boundary in Sudano-Sahelian West Africa: Interdisciplinary investigation at Fatandi V, Eastern Senegal

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243129
Author(s):  
Benoît Chevrier ◽  
Laurent Lespez ◽  
Brice Lebrun ◽  
Aline Garnier ◽  
Chantal Tribolo ◽  
...  
Keyword(s):  
Initial Phase ◽  
Raw Materials ◽  
Stone Age ◽  
Cultural Group ◽  
Western Africa ◽  
Late Stone Age ◽  
Depositional Processes ◽  
Cultural Pattern ◽  
History Of

The end of the Palaeolithic represents one of the least-known periods in the history of western Africa, both in terms of its chronology and the identification of cultural assemblages entities based on the typo-technical analyses of its industries. In this context, the site of Fatandi V offers new data to discuss the cultural pattern during the Late Stone Age in western Africa. Stratigraphic, taphonomical and sedimentological analyses show the succession of three sedimentary units. Several concentrations with rich lithic material were recognized. An in situ occupation, composed of bladelets, segments, and bladelet and flake cores, is confirmed while others concentrations of lithic materials have been more or less disturbed by erosion and pedogenic post-depositional processes. The sequence is well-dated from 12 convergent OSL dates. Thanks to the dating of the stratigraphic units and an OSL date from the layer (11,300–9,200 BCE [13.3–11.2 ka at 68%, 14.3–10.3 ka at 95%]), the artefacts are dated to the end of Pleistocene or Early Holocene. Palaeoenvironmental data suggest that the settlement took place within a mosaic environment and more precisely at the transition between the open landscape of savanna on the glacis and the plateau, and the increasingly densely-wooded alluvial corridor. These humid areas must have been particularly attractive during the dry season by virtue of their rich resources (raw materials, water, trees, and bushes). The Fatandi V site constitutes the first stratified site of the Pleistocene/Holocene boundary in Senegal with both precise geochronological and palaeoenvironmental data. It complements perfectly the data already obtained in Mali and in the rest of western Africa, and thus constitutes a reference point for this period. In any case, the assemblage of Fatandi V, with its bladelets and segments and in the absence of ceramics and grinding material, fits with a cultural group using exclusively geometric armatures which strongly differs from another group characterized by the production of bifacial armatures, accompanied in its initial phase by ceramics (or stoneware) and grinding material.

Engineering geology characterization of lacustrine overconsolidated clays in an alpine area of Italy

2000 ◽  
Vol 37 (6) ◽  
pp. 1241-1251
Author(s):  
R Meriggi ◽  
P Paronuzzi ◽  
L Simeoni
Keyword(s):  
Triaxial Compression ◽  
Mechanical Resistance ◽  
Compression Tests ◽  
Stress History ◽  
Depositional Processes ◽  
Geotechnical Characteristics ◽  
Lithostratigraphic Units ◽  
Overconsolidated Clays ◽  
History Of

This study reports the main geotechnical characteristics of the Steggio Clay unit, a lacustrine sequence located in a valley of the Veneto Piedmont area (northern Italy). Analyzing the variations of overconsolidation pressure with depth, and the compressibility characteristics of natural, swelled, and reconstituted samples, one can hypothesize about the existence and influence of swelling processes on the stress history of the deposit. The yield pressures, determined by oedometric tests for the various lithostratigraphic units, are compared with the preconsolidation pressures deduced from the geological analysis, and a reduction in apparent preconsolidation pressures is evident in the upper layers. Comparing the natural water content of each stratigraphic unit with that of the overconsolidated and normally consolidated states, it can be seen that the same layers are softened. These phenomena could have been caused by swelling induced by erosion of the overlying deposits, sliding of glacial masses, and unloading due to deglaciation. The results of undrained consolidated triaxial compression tests indicate that the variations between the parameters of mechanical resistance of some lithological units can be attributed to the different values of the void index, Ivo, corresponding to the lithostatic in situ stress.Key words: overconsolidated clays, stress history, swelling, intrinsic characteristics, post-depositional processes, glaciation.

scholarly journals An Early Stone Age in Western Africa? Spheroids and polyhedrons at Ounjougou, Mali

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Louis De Weyer
Keyword(s):  
Raw Materials ◽  
Middle Pleistocene ◽  
Industrial Complex ◽  
Stone Age ◽  
Stratigraphic Sequence ◽  
Western Africa ◽  
Shaping Process ◽  
The Future ◽  
Lithic Industry ◽  
Early Stone Age

Ounjougou stratigraphic sequence (Bandiagara, Dogon Country, Mali) is the most complete record in Western Africa for the Middle Pleistocene. This paper focuses on the lithic industry unearthed in the lowest levels of the sequence. Despite the impossibility to fix the dating of those layers, the assemblage clearly presents Oldowan features. A strong erosive process, combined to the absence of Acheulean industry, strengthens the idea of a probable ancient age for the lithic industry. Morphometric, Technological and techno-functional approaches were performed to study sandstone polyhedrons, spheroids and bolas, abundant in the collection, along with a flake production on quartz and quartzite pebbles. This study demonstrates that polyhedrons, spheroids and bolas were shaped from independent chaînes opératoires to realize specific tasks. The hypothesis of opportunistic knapping does not fit with these materials at Ounjougou. The evidence of shaping is highlighted by diacritic schemes showing that the flakes detached are not controlled for their usability, but for shaping the morphology of the spheroid. Apart from those polyhedrons and spheroids, flake production is also identified. While the shaping process is made on sandstone cobbles, sharp flakes are produced from quartz pebbles. This clear choice of different raw materials to produce shaped heavy tools in one hand and light flake tools in another hand strengthens the idea of a deliberate shaping of spheroid tools. The discussion compares this assemblage with other known assemblages like Ain Hanech and Olducai Gorge. Our point focus on the methodology used to study these specific artefacts, very different from one author to another. We stress out the fact that using the term ‘polyhedron’ is not accurate to define artefacts that can refer to shape tools or multifacial cores. We suggest to avoid using it and to focus on a technical identification to name the artefacts as cores or tools. The technological and techno-functional approaches are relevant to make this distinction. Then we propose some hypothesis about the use of spheroid and bolas and suggest experiments and traceological analyses in the future to confirm their functionality. Ounjougou lithic tool kit, composed of flake débitage, retouched flakes and shaped tools on pebbles, along with the spheroids and bolas component, gives an evidence of a diversified tool kit corresponding to the Oldowan Industrial Complex, and then represents the first Early Stone Age site in stratigraphy in Western Africa.

Middle and Later Stone Age Symbolism

Utafiti ◽  
2020 ◽  
Vol 15 (1) ◽  
pp. 1-27
Author(s):  
Pastory Magayane Bushozi
Keyword(s):  
Raw Materials ◽  
Behavioural Change ◽  
Middle Stone Age ◽  
Sub Saharan Africa ◽  
Historical Period ◽  
Stone Age ◽  
Later Stone Age ◽  
African Region ◽  
Late Stone Age ◽  
Sub Saharan

Abstract The archaeological remains found in the Mumba rock-shelter in northern Tanzania – where continuous deposits span from the Middle Stone Age (MSA) to the historical period – provide a unique opportunity to study trends in technology and behavioural change of early humans. Developments in symbolic thought may be evident in the production and use of ochre pigments, beads and rock art. At this site, beads and other symbolic artefacts are represented in varying quantities through the late MSA, the Later Stone Age (LSA), Neolithic, and post Stone Age cultures. Such beaded ornaments were made from various raw materials including ostrich eggshells, stone pebbles, and arthropod shells. Ancient beading technologies, discovered at Mumba and other MSA sites across the East African region, contribute to clarifying the origin and development of representational cognition in the distant past. These artefacts also reveal components of personal identity and creative expression, whose recorded remains are patchy and infrequently discussed in Sub-Saharan Africa. From a Darwinian perspective, these archaeological finds demonstrate the empirical issue of environmentally selected human responses to local stimuli. They are remnants of the synergistic adaptation that led more generally to the broader technological innovations and behavioural changes occurring through the late Middle Stone Age and later flourishing universally during the Late Stone Age culture.

scholarly journals North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. Alexis P. Rodriguez ◽  
Kenneth L. Tanaka ◽  
Ali M. Bramson ◽  
Gregory J. Leonard ◽  
Victor R. Baker ◽  
...  
Keyword(s):  
Katabatic Wind ◽  
Spiral Pattern ◽  
Near Surface ◽  
Valuable Source ◽  
History Of ◽  
North Polar ◽  
Human Exploration ◽  
Erosional Event

AbstractThe clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.

scholarly journals Development of a Field Deployable Firebrand Flux and Condition Measurement System

2020 ◽  
Author(s):  
Simone Zen ◽  
Jan C. Thomas ◽  
Eric V. Mueller ◽  
Bhisham Dhurandher ◽  
Michael Gallagher ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Time History ◽  
Infrared Camera ◽  
Thermal Conditions ◽  
Particle Characterization ◽  
Fire Dynamics ◽  
Rate Of Spread ◽  
New Instrument ◽  
History Of

AbstractA new instrument to quantify firebrand dynamics during fires with particular focus on those associated with the Wildland-Urban Interface (WUI) has been developed. During WUI fires, firebrands can ignite spot fires, which can rapidly increase the rate of spread (ROS) of the fire, provide a mechanism by which the fire can pass over firebreaks and are the leading cause of structure ignitions. Despite this key role in driving wildfire dynamics and hazards, difficulties in collecting firebrands in the field and preserving their physical condition (e.g. dimensions and temperature) have limited the development of knowledge of firebrand dynamics. In this work we present a new, field-deployable diagnostic tool, an emberometer, designed to provide measurement of firebrand fluxes and information on both the geometry and the thermal conditions of firebrands immediately before deposition by combining a visual and infrared camera. A series of laboratory experiments were conducted to calibrate and validate the developed imaging techniques. The emberometer was then deployed in the field to explore firebrand fluxes and particle conditions for a range of fire intensities in natural pine forest environments. In addition to firebrand particle characterization, field observations with the emberometer enabled detailed time history of deposition (i.e. firebrand flux) relative to concurrent in situ fire behaviour observations. We highlight that deposition was characterised by intense, short duration “showers” that can be reasonably associated to spikes in the average fire line intensity. The results presented illustrate the potential use of an emberometer in studying firebrand and spot fire dynamics.

scholarly journals Architectural ruins: geoculture of the anatomy of buildings as illustrated by Casa Ippolito, Malta

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Lino Bianco
Keyword(s):  
Material Culture ◽  
Building Materials ◽  
Raw Materials ◽  
Primary Source ◽  
Secondary Sources ◽  
Non Invasive ◽  
History Of ◽  
Aerial Vehicle ◽  
Materials Used ◽  
Building Physics

AbstractRuins are a statement on the building materials used and the construction method employed. Casa Ippolito, now in ruins, is typical of 17th-century Maltese aristocratic country residences. It represents an illustration of secondary or anthropogenic geodiversity. This paper scrutinises these ruins as a primary source in reconstructing the building’s architecture. The methodology involved on-site geographical surveying, including visual inspection and non-invasive tests, a geological survey of the local lithostratigraphy, and examination of notarial deeds and secondary sources to support findings about the building’s history as read from its ruins. An unmanned aerial vehicle was used to digitally record the parlous state of the architectural structure and karsten tubes were used to quantify the surface porosity of the limestone. The results are expressed from four perspectives. The anatomy of Casa Ippolito, as revealed in its ruins, provides a cross-section of its building history and shows two distinct phases in its construction. The tissue of Casa Ippolito—the building elements and materials—speaks of the knowledge of raw materials and their properties among the builders who worked on both phases. The architectural history of Casa Ippolito reveals how it supported its inhabitants’ wellbeing in terms of shelter, water and food. Finally, the ruins in their present state bring to the fore the site’s potential for cultural tourism. This case study aims to show that such ruins are not just geocultural remains of historical built fabric. They are open wounds in the built structure; they underpin the anatomy of the building and support insights into its former dynamics. Ruins offer an essay in material culture and building physics. Architectural ruins of masonry structures are anthropogenic discourse rendered in stone which facilitate not only the reconstruction of spaces but also places for human users; they are a statement on the wellbeing of humanity throughout history.

scholarly journals In Situ exploration of the giant planets

2021 ◽  
Author(s):  
O. Mousis ◽  
D. H. Atkinson ◽  
R. Ambrosi ◽  
S. Atreya ◽  
D. Banfield ◽  
...  
Keyword(s):  
Solar System ◽  
Giant Planets ◽  
Atmospheric Composition ◽  
Formation History ◽  
History Of ◽  
Composition Structure ◽  
Galileo Probe ◽  
Probe Measurements

AbstractRemote sensing observations suffer significant limitations when used to study the bulk atmospheric composition of the giant planets of our Solar System. This impacts our knowledge of the formation of these planets and the physics of their atmospheres. A remarkable example of the superiority of in situ probe measurements was illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases’ abundances and the precise measurement of the helium mixing ratio were only made available through in situ measurements by the Galileo probe. Here we describe the main scientific goals to be addressed by the future in situ exploration of Saturn, Uranus, and Neptune, placing the Galileo probe exploration of Jupiter in a broader context. An atmospheric entry probe targeting the 10-bar level would yield insight into two broad themes: i) the formation history of the giant planets and that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. An atmospheric probe could represent a significant ESA contribution to a future NASA New Frontiers or flagship mission to be launched toward Saturn, Uranus, and/or Neptune.

scholarly journals Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

2017 ◽  
Vol 12 (S330) ◽  
pp. 148-151 ◽  
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Sun ◽  
Thick Disc ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

scholarly journals The merger-driven evolution of massive early-type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 62-66
Author(s):  
Carlo Cannarozzo ◽  
Carlo Nipoti ◽  
Alessandro Sonnenfeld ◽  
Alexie Leauthaud ◽  
Song Huang ◽  
...  
Keyword(s):  
Mass Velocity ◽  
Selection Criteria ◽  
Velocity Dispersion ◽  
Ex Situ ◽  
Scaling Relations ◽  
Early Type ◽  
History Of ◽  
Kinematic Properties ◽  
Shed Light

AbstractThe evolution of the structural and kinematic properties of early-type galaxies (ETGs), their scaling relations, as well as their stellar metallicity and age contain precious information on the assembly history of these systems. We present results on the evolution of the stellar mass-velocity dispersion relation of ETGs, focusing in particular on the effects of some selection criteria used to define ETGs. We also try to shed light on the role that in-situ and ex-situ stellar populations have in massive ETGs, providing a possible explanation of the observed metallicity distributions.

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