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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Benthic habitats of the extended Faial Island shelf and their relationship to geologic, oceanographic and infralittoral biologic features

Tempera, Fernando January 2009 (has links)
This thesis presents a new template for multidisciplinary habitat mapping that combines the analyses of seafloor geomorphology, oceanographic proxies and modelling of associated biologic features. High resolution swath bathymetry of the Faial and western Pico shelves is used to present the first state-of-the-art geomorphologic assessment of submerged island shelves in the Azores. Solid seafloor structures are described in previously unreported detail together with associated volcanic, tectonic and erosion processes. The large sedimentary expanses identified in the area are also investigated and the large bedforms identified are discussed in view of new data on the local hydrodynamic conditions. Coarse-sediment zones of types hitherto unreported for volcanic island shelves are described using swath data and in situ imagery together with sub-bottom profiles and grainsize information. The hydrodynamic and geological processes producing these features are discussed. New oceanographic information extracted from satellite imagery is presented including yearly and seasonal sea surface temperature and chlorophyll-a concentration fields. These are used as proxies to understand the spatio-temporal variability of water temperature and primary productivity in the immediate island vicinity. The patterns observed are discussed, including onshore-offshore gradients and the prevalence of colder/more productive waters in the Faial-Pico passage and shelf areas in general. Furthermore, oceanographic proxies for swell exposure and tidal currents are derived from GIS analyses and shallow-water hydrographic modelling. Finally, environmental variables that potentially regulate the distribution of benthic organisms (seafloor nature, depth, slope, sea surface temperature, chlorophyll-a concentration, swell exposure and maximum tidal currents) are brought together and used to develop innovative statistical models of the distribution of six macroalgae taxa dominant in the infralittoral (articulated Corallinaceae, Codium elisabethae, Dictyota spp., Halopteris filicina, Padina pavonica and Zonaria tournefortii). Predictive distributions of these macroalgae are spatialized around Faial island using ordered logistic regression equations and raster fields of the explanatory variables found to be statistically significant. This new approach represents a potentially highly significant step forward in modelling benthic communities not only in the Azores but also in other oceanic island shelves where the management of benthic species and biotopes is critical to preserve ecosystem health.
42

Block och skärvig sten. En arkeologi av det abiotiska : Ett symmetriskt perspektiv på blockanläggningar från yngre bronsålder - äldre järnålder med utgångspunkt i Kättsta i Uppland.

Bergström, Philip January 2016 (has links)
This dissertation investigates how a symmetrical approach to archaeology can be applied to identify the properties and effects of the non-living, abiotic materials. And to reconfigure the relationship between humans and non-human objects, bridging the divide between what has been termed ‘cultural’ and ‘natural’ and thus placed in different ontological realms. This is examined by studying the practices surrounding “boulder graves”, from the Late Bronze Age - Early Iron Age (approx. 1000 – 0 BC) in Kättsta, Ärentuna parish in Uppland, Sweden. The boulders tend to be studied from an anthropocentric point of view, in which they are seen primarily as passive objects, interpreted only for what they represent. The objective of this research, however, is to gain new insights into the agency of boulders, and how they contributed to the practices carried out adjacent to them. The dissertation is based on a case study where a thematic analysis is performed, focusing on the properties and characteristics of boulders, their affordances, the distribution of finds and their interrelations, and the effects their relations generated. The results show that the boulders themselves contributed in human-stone relations and were vital in the formation of the grave-like features they became part of. It is argued that a symmetrical, non-anthropocentric approach to these features will broaden our view on materialities in the past, affording ontological as well as ecological implications.

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