• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 9
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 24
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
11

Palynological analysis from a bush karoo rat (Otomys unisulcatus) lodge near Prince Albert, South Africa

Patrickson, Shela 09 March 2017 (has links)
The "desertification" debate surrounding the Karoo Biome of South Africa has recently inspired much research in this region. The preservation of pollen in middens in arid environments from different parts of the world has great potential for the reconstruction of past vegetation. A lodge of the bush karoo rat (Otomys unisulcatus) was excavated near Prince Albert, South Africa, and the high numbers of well-preserved pollen grains was analysed. The vegetation reconstruction suggested that there was a decline in grasses over the whole sequence, while the vegetation experienced several short-term fluctuations throughout the time period. The ages within the lodge were uncertain, although the material is likely to be modern. The palynological analysis appear to be reliable and corresponds relatively well with other studies. The lodges of these species could therefore provide an exciting new source of historical pollen in the arid regions of southern Africa.
12

Statistical aspects of automatic pollen identification

Karaman, Ali Emre January 2000 (has links)
No description available.
13

Tertiary fossil wood in South Eastern Australia

O'Brien, Jane, n/a January 1999 (has links)
Palaeobotany illuminates past environments by relating the fossilised species to the existing geological conditions. This has previously been done with fossilised leaves and spores but not with fossilised wood. The recovery of a significant quantity of wood from an area of Tertiary sediments in New South Wales, enabled the used of fossilised wood as a palaeoenvironmental tool. Tertiary sedimentary deposits of south eastern Australia are diverse lithologically, occupy distinct areas and are limited in vertical and horizontal extent. However, samples in museum collections together with samples from field work and descriptions of fossil wood from previous researchers enabled an analysis of the fossil wood. The geological and palaeontological aspects of the fossil wood were considered for each specimen. Only specimens with precise information concerning location and description of the sedimentary deposits in which the specimens were found were investigated. Lithology, sedimentary structures and the relationship with surrounding geological units were also considered. The samples were then classified and identified. It was possible to identify fossil wood to Family level by comparison with existing taxa. In the majority of cases, identification to species level was not possible due to the lack of detail in the specimen and because features such as colour cannot be used with fossilised specimens. With Australian fossilised wood, a systematic nomenclature based on structure observed within the palaeotaxa, would be more relevant. Comparisons of cell structures with previous work on palaeoenvironmental indicators was found to be possible. Fossil wood has two uses. Firstly, as a local environmental indicator, usually in conjunction with sedimentological data, assessing the rate and direction of water flow, types of depositional environments and localised floral assemblages. Secondly, as an indicator of regional climate. Within any one particular time period, comparisons between the cellular structures of wood found in different parts of south eastern Australia show gross changes in cell size, mean growth ring size and vessel size, which enabled generalisations about climate for each epoch in the Tertiary. Palaeoclimatic indicators from the wood concurred with previous climatic interpretations based on palynology and sedimentology. Cool conditions during the Palaeocene were clearly indicated by small cells and small growth rings which gradually increased throughout the remainder of the Tertiary. Several areas e.g., Dargo High Plains, where cold conditions existed in isolation could be clearly distinguished. This corresponds with the gradual northward movement of the Australian plate with consequent increasing temperatures on the mainland.
14

Flora of the Ravenscrag Formation of the Big Muddy Valley, Willow Bunch Lake map area (72H), Saskatchewan

Postnikoff, Andrew Corbin Lindsay 03 February 2009
Paleocene aged beds of the Ravenscrag Formation exposed in the Big Muddy Valley of Southern Saskatchewan produce numerous plant fossils. Studies into these fossils last occurred in the 1930s. Studies into the contemporaneous Ravenscrag Butte flora of southwestern Saskatchewan have shown that the flora of these beds needed updating. Collections of specimens and stratigraphic sections were taken from the area.<p> Forty species, including two new species and seven unknowns were identified. <i>Elatocladus megasequoiae</i> n.sp. and <i>Corvirupestrobus adrielensis</i> n.sp. are both Conifers, and <i>Corvirupestrobus</i> is also a new genus. Many species were previously unknown in Ravenscrag Formation floras, including cf.<i>Lygodium</i> sp., <i>Thelypteris</i> sp., <i>Sparganium</i> sp.,<i> Paloreodoxites plicata </i> (Lesquereux) Knowlton, <i>Carya antiquorum</i> Newberry and <i>Nordenskioldia borealis</i> Heer. Two new combinations are proposed, transferring <i>Quercus praegroenlandica</i> Berry to <i>Fagopsiphyllum praegroenlandicum</i> (Berry) n. comb. and <i>Harmsia hydrocotoloidea</i> McIver and Basinger to <i>Harmsvernia hydrocotoloidea</i> (McIver and Basinger) n. comb., with <i>Harmsvernia</i> a new genus.<p> Three sub-floras are recognized for this flora. Sub-flora 1 is a conifer dominated swamp sub-flora, common to many Paleocene localities. Sub-flora 2 is a conifer dominated sub-flora suspected of being from a drier environment than florule 1. Elements of sub-flora 1 appear in sub-flora 2 and vice versa, but relative abundances differ. There is little taxonomic overlap between sub-floras 1 and 2 with sub-flora 3. Sub-flora 3 is more typical of contemporaneous localities to the south such as those of the Bear Den Member of the Golden Valley Formation (Hickey 1977), whereas sub-floras 1 and 2 are more typical of northern localities, like the Genesee locality (Chandrasekharam 1974) and Koryak Formation (Golovneva 1994). The Big Muddy Valley occurs at the ecotone between the Arctic floras and the floras of the South.<p> The taxonomy of Glyptostrobus from the Paleocene is revised as an appendix, written as a separate report. This revision is more extensive than for the other taxa of this study, utilizing materials from numerous other localities, including the Joffre Bridge Roadcut localities (Hoffman and Stockey 1999), the Smokey Tower localities (Christophel 1976) and the Buchanan Lake Formation (Basinger 1991).
15

Flora of the Ravenscrag Formation of the Big Muddy Valley, Willow Bunch Lake map area (72H), Saskatchewan

Postnikoff, Andrew Corbin Lindsay 03 February 2009 (has links)
Paleocene aged beds of the Ravenscrag Formation exposed in the Big Muddy Valley of Southern Saskatchewan produce numerous plant fossils. Studies into these fossils last occurred in the 1930s. Studies into the contemporaneous Ravenscrag Butte flora of southwestern Saskatchewan have shown that the flora of these beds needed updating. Collections of specimens and stratigraphic sections were taken from the area.<p> Forty species, including two new species and seven unknowns were identified. <i>Elatocladus megasequoiae</i> n.sp. and <i>Corvirupestrobus adrielensis</i> n.sp. are both Conifers, and <i>Corvirupestrobus</i> is also a new genus. Many species were previously unknown in Ravenscrag Formation floras, including cf.<i>Lygodium</i> sp., <i>Thelypteris</i> sp., <i>Sparganium</i> sp.,<i> Paloreodoxites plicata </i> (Lesquereux) Knowlton, <i>Carya antiquorum</i> Newberry and <i>Nordenskioldia borealis</i> Heer. Two new combinations are proposed, transferring <i>Quercus praegroenlandica</i> Berry to <i>Fagopsiphyllum praegroenlandicum</i> (Berry) n. comb. and <i>Harmsia hydrocotoloidea</i> McIver and Basinger to <i>Harmsvernia hydrocotoloidea</i> (McIver and Basinger) n. comb., with <i>Harmsvernia</i> a new genus.<p> Three sub-floras are recognized for this flora. Sub-flora 1 is a conifer dominated swamp sub-flora, common to many Paleocene localities. Sub-flora 2 is a conifer dominated sub-flora suspected of being from a drier environment than florule 1. Elements of sub-flora 1 appear in sub-flora 2 and vice versa, but relative abundances differ. There is little taxonomic overlap between sub-floras 1 and 2 with sub-flora 3. Sub-flora 3 is more typical of contemporaneous localities to the south such as those of the Bear Den Member of the Golden Valley Formation (Hickey 1977), whereas sub-floras 1 and 2 are more typical of northern localities, like the Genesee locality (Chandrasekharam 1974) and Koryak Formation (Golovneva 1994). The Big Muddy Valley occurs at the ecotone between the Arctic floras and the floras of the South.<p> The taxonomy of Glyptostrobus from the Paleocene is revised as an appendix, written as a separate report. This revision is more extensive than for the other taxa of this study, utilizing materials from numerous other localities, including the Joffre Bridge Roadcut localities (Hoffman and Stockey 1999), the Smokey Tower localities (Christophel 1976) and the Buchanan Lake Formation (Basinger 1991).
16

The eocene megafossil flora of Nerriga, New South Wales / by Robert S. Hill

Hill, Robert Stephen January 1980 (has links)
Typescript (photocopy) / 2 v. (524 leaves) : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1981
17

The Coexistence Approach-Theoretical Background and Practical Considerations of Using Plant Fossils for Climate Quantification

Utescher, T., Bruch, A. A., Erdei, B., Franҫois, L., Ivanov, D., Jacques, F. M.B., Kern, A. K., Liu, Y. S.C., Mosbrugger, V., Spicer, R. A. 05 September 2014 (has links)
The Coexistence Approach was established by Mosbrugger and Utescher (1997) as a plant-based method to reconstruct palaeoclimate by considering recent climatic distribution ranges of the nearest living relatives of each fossil taxon. During its existence for over more than 15. years, its basics have been tested and reviewed in comparison with other terrestrial and marine climate reconstruction techniques and climate modelling data. However, some controversies remain about its underlying data or its applicability in general.In view of these controversies this paper discusses the power and limitations of the Coexistence Approach by summarising past results and new developments. We give insights into the details and problems of each step of the application from the assignment of the fossil plant to the most suitable nearest living relative, the crucial consideration of the usefulness of specific taxa towards their climatic values and the correct interpretation of the software-based suggested palaeoclimatic intervals. Furthermore, we reflect on the fundamental data integrated in the Coexistence Approach by explaining different concepts and usages of plant distribution information and the advantages and disadvantages of modern climatic maps. Additionally, we elaborate on the importance of continually updating the information incorporated in the database due to new findings in e.g., (palaeo-)botany, meteorology and computer technology.Finally, for a transparent and appropriate use, we give certain guidelines for future applications and emphasize to users how to carefully consider and discuss their results. We show the Coexistence Approach to be an adaptive method capable of yielding palaeoclimatic and palaeoenvironmental information through time and space.
18

Les paléoflores du Jurassique moyen et supérieur (Bathonien - Oxfordien) du bassin parisien et de ses marges / Middle and upper Jurassic Paleoflora (Bathonian - Oxfordian) of Paris basin and its margins

Le Couls, Matthieu 13 December 2017 (has links)
La paléoflore du Jurassique moyen et supérieur du bassin parisien est documentée par un ensemble de gisements assez importants et relativement peu connus, contenant des fossiles de tous types, généralement sous forme d’empreintes avec ou sans cuticule, ou encore sous forme de silicification dans des chailles. Huit gisements historiques ou nouveaux ont été étudiés, plus quatre fossiles isolés, tous datant de l’intervalle Bathonien-Oxfordien, et répartis sur l’ensemble du bassin parisien et de ses marges. Trois gisements ont étés étudiés dans la partie Est du bassin, Il s’agit d’Arc-en-Barrois (Bathonien supérieur), d’Étrochey (Callovien inférieur et moyen) et de Laignes (Callovien moyen). Ils appartiennent tous à l’archipel de la plate-forme bourguignonne, dont les îles étaient alors couvertes d’une forêt mixte xérophytes à Brachyphyllum. Le gisement d’Auxey, situé plus au sud, près de Beaune, daté de l’Oxfordien supérieur, montre au contraire une flore de milieu humide, riche en fougères. Deux autres gisements ont été étudiés au niveau du seuil du Poitou, les flores du Callovien moyen de Sauzé-Vaussais et des environs de Poitiers, riches en bennettitales, correspondant probablement à des milieux xéromorphes assez ouverts. Enfin, deux derniers gisements ont étés étudiés dans l’ouest du bassin, sur la marge orientale du massif armoricain alors émergé, les flores du Bathonien supérieur de Mamers et de Nonant-le-Pin. Ces deux gisements correspondent à des forêts mixtes côtières à Brachyphyllum, dans un milieu également xéromorphe. Ainsi, le bassin parisien présente au Bathonien et au Callovien exclusivement des flores côtières xérophytes, correspondant à des paléoenvironnements plutôt fermés, comme sur la plate-forme bourguignonne, jusqu’à des milieux au contraire assez ouverts, comme dans le Poitou. Les flores de milieu interne, loin des côtes, ne sont pas connues pour cette période. À l’Oxfordien supérieur en revanche, la flore d’Auxey indiquerait plutôt une certaine humidification du climat, bien que de plus amples données soient nécessaires pour confirmer cette interprétation. / The palaeoflora of Late and Middle Jurassic of the Paris basin is documented by a set of rather important outcrops, relatively little know, containing fossils of every type, mainly imprints often without cuticle, sometime with, or otherwise silicification in flint nodules. Eight historic or new outcrops were studied, plus four isolated fossils, all dating from the Bathonian-Oxfordian interval and distributed on the whole Paris basin and its margins. Three deposits were studied in the eastern part of the basin, its Arc-en-Barrois (late Bathonian), Étrochey (early and middle Callovian), and Laignes (middle Callovian). They all belong to the archipelago of the Burgundian platform, whose islands are covered by a mixed xerophytes Brachyphyllum forest. The deposit of Auxey, situated to the south, close to the city of Beaune, dated of late Oxfordian shows on the contrary a flora of wet environments, rich in ferns. Two others outcrops were studied close to the seuil du Poitou, the late Callovian flora of Sauzé-Vaussais and Poitiers surroundings, rich in bennettitales, presumably corresponding to relatively open xeromorphic environments. Finally, two last deposits were studied in the west of the basin, on the oriental margin of the emerged Armorican massif, the flora of the late Bathonian of Mamers and Nonant-le-Pin. These two outcrops correspond to a coastal mixed Brachyphyllum forest, also in a xeromorphic environment. Thereby, the Paris basin presents from Bathonian to Callovian exclusively xerophytes floras, corresponding to rather closed paleoenvironments, as on the Burgundian platform, to on the contrary opened enough environments, as in Poitou. The flora of internal environments, far from coasts, are not known for this period. In late Oxfordian on the other hand, the flora of Auxey would indicate rather a certain moistering of the climate, although more ample data are necessary to confirm this interpretation.
19

Recursos forestales en un medio semiárido. Nuevos datos antracológicos para la Región de Murcia desde la Edad del Bronce hasta época medieval

García Martínez, María Soledad 23 July 2009 (has links)
Esta tesis doctoral recoge el estudio antracológico de los materiales leñosos carbonizados de cinco yacimientos arqueológicos de la Región de Murcia cuya secuencia cronológica cubre los últimos 3800 años, desde la Edad del Bronce hasta la época medieval. Los yacimientos estudiados son concretamente La Punta de los Gavilanes (Mazarrón), con ocupación desde la Edad del Bronce hasta mediados del siglo I a.C.; Barranco de la Viuda (Lorca), con un único momento de ocupación asociado al Bronce Argárico; el Balneario Romano de Archena, cuya cronología se sitúa en torno al siglo I d.C.; los materiales constructivos carbonizados del Teatro Romano de Cartagena y, finalmente, el enclave de los siglos XII y XIII localizado en la Calle Santa María nº 19 de Jumilla.Los resultados obtenidos se insertan en el contexto del Sureste de la Península Ibérica a partir de su discusión con las secuencias polínicas y antracológicas publicadas para esta zona. / This doctoral thesis contains the charcoal analysis of the charred materials from five archaeological sites of the Región de Murcia, whose chronological sequence covers the last 3800 years, from the Bronze Age to the medieval period. The studied sites are concretely Punta de los Gavilanes (Mazarrón), occupied from the Bronze Age to the I century BC; Barranco de la Viuda (Lorca), with one moment of occupation associated to the Argaric Bronze; Balneario Romano de Archena, whose chronology is around the I century AD; the charred building materials of the Teatro Romano de Cartagena and, finally, the medieval site (XII and XIII centuries) located in the Calle Santa Maria nº 19 of Jumilla.The results are inserted in the context of the Southeastern Iberian Peninsula by means of their discussion with published pollen and charcoal sequences from this zone.
20

The late quaternary palaeoenvironments of a subalpine wetland in Cathedral Peak, KwaZulu-Natal Drakensberg.

Lodder, Jared. January 2011 (has links)
In contrast to the wealth of palaeoenvironmental research stemming from the eastern Afromontane archipelago, the southern Afromontane component, which comprises largely of the Drakensberg, remains understudied. The Drakensberg constitute an area of significant biodiversity, cultural and economic importance. Suitable sites for palaeoenvironmental research are rare in South Africa due to general arid climatic conditions over much of the country. The KwaZulu-Natal Drakensberg offers a unique opportunity for palaeoenvironmental research through its increased rainfall and higher altitudes, which enable the development of wetlands that have the potential for polliniferous accumulation to occur. Catchment Six in Cathedral Peak is one such wetland that has provided an opportunity to research palaeoenvironmental conditions of the southern Afromontane archipelago component. A 371 cm sediment core was extracted from a subalpine wetland in Catchment Six and analysed using multiple proxies including; pollen, charcoal and geochemistry (carbon and nitrogen stable isotopes). A chronological framework for the core was established based on accelerated mass spectrometry radiocarbon dating of eight bulk sediment samples. A basal date of 15,100 ± 445 cal yr BP was determined at a depth of 298 cm. Poor pollen preservation of the basal portion of the core limited palaeoenvironmental inference for the late Pleistocene section of the record. The multiproxy record provides high chronological resolution for the early to late Holocene. Multi-proxy data indicate that the Holocene period in the Drakensberg was characterised by variable climatic conditions. Charcoal data indicate periods of increased regional fires in the last ca. 400 cal yr BP. Palaeoenvironmental inferences from the Catchment Six record are broadly in agreement with regional climatic indications based on existing literature. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Page generated in 1.4399 seconds