1,720,957 research outputs found
The Quaternary of the Jurassic Coast Region: From The Neogene to the Anthropocene
Full text linkThe Jurassic Coast World Heritage Sites (JCWHS) is not only a 95 km long coastline and remarkable Mesozoic geological section, but also a slice through a Quaternary landscape. For the majority of the last two million years this landscape lay in the periglacial zone, just south of a waxing and waning ice margin and just north of an Atlantic inlet which eventually became the English Channel. This paper reviews how the previous landscape inherited from the Cenozoic, was modified through uplift, climatically driven fluvial activity and periglaciation. Much evidence of this Quaternary history can be seen today in sections along the JCWHS coast which cuts through a number of headwater valleys the largest of which are the Exe and Axe. Recent studies, largely funded from the Aggregate Levy Tax, have produced the first independent chronologies for the Exe and Axe valleys and a model of how periglaciation interacted with the layer-cake stratigraphy of the Mesozoic bedrocks of the JCWHS. The Quaternary history of the JCWHS is also preserved in raised beaches on the Isle of Portland, coastal landforms, and in Holocene alluvial sediments associated with human activity and which may constitute part of the putative Anthropocene. An appreciation of the Quaternary history of the JCWHS is also important in understanding modern geological hazards from landslides to flooding.<br/
A stacked Late Quaternary fluvio-periglacial sequence from the Axe valley, southern England with implications for landscape evolution and Palaeolithic archaeology
Full text linkThe current model of mid-latitude late Quaternary terrace sequences, is that they are uplift-driven but climatically controlled terrace staircases, relating to both regional-scale crustal and tectonic factors, and palaeohydrological variations forced by quasi-cyclic climatic conditions in the 100 K world (post Mid Pleistocene Transition). This model appears to hold for the majority of the river valleys draining into the English Channel which exhibit 8–15 terrace levels over approximately 60–100 m of altitudinal elevation. However, one valley, the Axe, has only one major morphological terrace and has long-been regarded as anomalous. This paper uses both conventional and novel stratigraphical methods (digital granulometry and terrestrial laser scanning) to show that this terrace is a stacked sedimentary sequence of 20–30 m thickness with a quasi-continuous (i.e. with hiatuses) pulsed, record of fluvial and periglacial sedimentation over at least the last 300–400 K yrs as determined principally by OSL dating of the upper two thirds of the sequence. Since uplift has been regional, there is no evidence of anomalous neotectonics, and climatic history must be comparable to the adjacent catchments (both of which have staircase sequences) a catchment-specific mechanism is required. The Axe is the only valley in North West Europe incised entirely into the near-horizontally bedded chert (crypto-crystalline quartz) and sand-rich Lower Cretaceous rocks creating a buried valley. Mapping of the valley slopes has identified many large landslide scars associated with past and present springs. It is proposed that these are thaw-slump scars and represent large hill-slope failures caused by Vauclausian water pressures and hydraulic fracturing of the chert during rapid permafrost melting. A simple 1D model of this thermokarstic process is used to explore this mechanism, and it is proposed that the resultant anomalously high input of chert and sand into the valley during terminations caused pulsed aggradation until the last termination. It is also proposed that interglacial and interstadial incision may have been prevented by the over-sized and interlocking nature of the sub-angular chert clasts until the Lateglacial when confinement of the river overcame this immobility threshold. One result of this hydrogeologically mediated valley evolution was to provide a sequence of proximal Palaeolithic archaeology over two MIS cycles. This study demonstrates that uplift tectonics and climate alone do not fully determine Quaternary valley evolution and that lithological and hydrogeological conditions are a fundamental cause of variation in terrestrial Quaternary records and landform evolutio
Eels, beavers and horses: Human niche construction in the European Late Upper Palaeolithic.
Full text linkIn this paper we explore interactions between co-occupants of riverine niches in north-west Europe during the Late Upper Palaeolithic using both ecological and archaeological data. It is argued that consideration of both the Lateglacial record and autecology of eel, beaver and horse supports a reinterpretation of some famous but enigmatic panels of Magdalenian mobiliary art as representations of eel fishing, along with horse and beaver exploitation in disturbed riverine habitats.The key contributions are:1) A new interpretation of key Palaeolithic art objects that highlights the importance of studying Palaeolithic art in its broader ecological and archaeological context, rather than continuing to focus on the iconographic features and interpret them in isolation.2) The application of a novel theoretical approach combining archaeology, ecology and palaeoecology which allowed us to suggest that a humanly co-constructed niche in ecological, nutritional, and symbolic terms, was also advantageous for human well-being and social development during the Late Upper Palaeolithic.<br/
The Quaternary rivers of the Jurassic Coast region: From the Neogene to the Anthropocene
No full textThe Jurassic Coast World Heritage Sites (JCWHS) is not only a 95 km long coastline and remarkable Mesozoic geological section, but also a slice through a Quaternary landscape. For the majority of the last two million years this landscape lay in the periglacial zone, just south of a waxing and waning ice margin and just north of an Atlantic inlet which eventually became the English Channel. This paper reviews how the previous landscape inherited from the Cenozoic, was modified through uplift, climatically driven fluvial activity and periglaciation. Much evidence of this Quaternary history can be seen today in sections along the JCWHS coast which cuts through a number of headwater valleys the largest of which are the Exe and Axe. Recent studies, largely funded from the Aggregate Levy Tax, have produced the first independent chronologies for the Exe and Axe valleys and a model of how periglaciation interacted with the layer-cake stratigraphy of the Mesozoic bedrocks of the JCWHS. The Quaternary history of the JCWHS is also preserved in raised beaches on the Isle of Portland, coastal landforms, and in Holocene alluvial sediments associated with human activity and which may constitute part of the putative Anthropocene. An appreciation of the Quaternary history of the JCWHS is also important in understanding modern geological hazards from landslides to flooding
Eels, Beavers, and Horses: Human Niche Construction in the European Late Upper Palaeolithic
No full textThis paper examines interactions between co-occupants of riverine niches in north-west Europe during the Late Upper Palaeolithic using both ecological and archaeological data. It is argued that consideration of both the Lateglacial record and autecology of eel, beaver and horse supports a reinterpretation of some famous but enigmatic panels of Magdalenian mobiliary art as representations of eel fishing, along with horse and beaver exploitation in disturbed riverine habitats. It is further suggested that this constitutes a humanly co-constructed niche in ecological, nutritional, and symbolic terms, which was also particularly advantageous for human well-being and social development in this time and place
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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