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1
Martin, Yvonne. "Modelling geomorphology in landscape evolution." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0030/NQ27198.pdf.
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Hurst, Martin David. "Hillslope morphology as an indicator of landscape evolution in tectonically active landscapes." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/12228.
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Hillslopes comprise the majority of unglaciated upland landscapes; they are the primary source for the production of sediment from bedrock, and the routing system by which sediment is delivered to the channel network. Yet the nature of hillslope response to changes in tectonic, climatic or base-level boundary conditions is poorly understood in terms of the spatial and temporal distribution of hillslope morphology. Here I exploit a previously published framework for exploring hillslope morphology in high relief landscapes (Roering et al., 2007), to address several critical questions: Does high resolution topography allow understanding of the processes and rates by which sediment is redistributed on hillslopes? If so, can hillslope morphology be used to map the spatial distribution of erosion rates and facilitate interpretation of the timing and magnitude of tectonic forcing, particularly in transient landscapes which are adjusting their erosion rates? And to what extent does variation in lithology influence hillslope evolution and morphology, and the ability to interpret process rates from hillslope form? In this thesis I sought to explain hillslope adjustment to changing boundary conditions through combining the predictions of analytical and numerical models with detailed analysis of real, high resolution topographic datasets (derived from LiDAR), focusing on two landscapes where the influence of tectonic forcing on base-level history is relatively well constrained, the Middle Fork Feather River in the northern Sierra Nevada, and the Dragon’s Back Pressure Ridge, on the Carrizo Plain, both in California. The Sierra Nevada of California is a west-tilted fault block composed primarily of granitoids formed during Mesozoic arc volcanism. The block underwent acceleration in uplift 5 - 3.5 Ma which is hypothesised to be caused be the drop-off of a dense root from the lower crust and replacement by hot asthenosphere, causing crustal buoyancy. A relict landscape has thus been uplifted and dissected by the major drainage routes crossing the range, which have eroded rapidly to form deep canyons. The fluvial network is characterised by breaks in slope (knickpoints) which migrate into the landscape to transmit the signal of increased erosion, setting baselevel conditions for adjacent hillslopes. Theoretical predictions for the morphology of hillslopes governed by a nonlinear sediment transport law, if the hillslopes have attained steady state (i.e. they are eroding in concert with base-level fall in adjacent valleys) reveal that the curvature of hilltops will be linearly proportional to erosion rates or rate of base-level fall. I present innovative techniques to extract hilltop networks and sample their adjacent hillslopes in order to test the utility of hilltop curvature for estimating erosion rates. This work is carried out in granitoid lithologies where the influence of bedrock heterogeneity is assumed no to be a first order control on hillslope morphology. Existing and new cosmogenic radionuclide analyses in the Feather River basin, California, suggest that erosion rates vary by over an order of magnitude from the remnant upland landscape to the incised river canyon. Hilltop curvature increases with erosion rates, allowing calibration of the hillslope sediment transport coefficient, which controls the relationship between hillslope gradient and sediment flux. This in turn allows the estimation of erosion rates throughout the landscape by mapping the spatial distribution of hilltop curvature. Additionally, despite the landscape containing gradient-limited hillslopes, hilltop curvature continues to increase with rising erosion rates, reflecting higher erosion rates than can be predicted by hillslope gradient. The distribution of hillslope morphology conforms well to predictions of a nonlinear sediment transport model, with measured values of hillslope relief varying with the product of hilltop curvature and hillslope length (proxy for erosion rate) in a manner similar to that predicted by Roering et al. (2007). Hilltop curvature can thus be used to estimate erosion rates in landscapes undergoing a transient adjustment to changing boundary conditions provided that the response timescale of hillslopes is short relative to channels. Having focused on a landscape with roughly uniform bedrock geology to isolate drivers of geomorphic change, I sought to evaluate whether these techniques could be extended across lithologic contacts and throughout the landscape. Underlying geology influences the efficacy of soil production and transport on hillslopes, and resistance to erosion by valley-forming processes. Here, quantitative analysis of LiDAR digital terrain models was performed to search for a topographic signature in two distinct lithologies in the Feather River catchment in northern California; granodiorite and deformed volcanics. The two sites, separated by <2 km and spanning similar elevations, are assumed to have similar climatic and denudation histories. Responding to increased erosion rates, transient hillslopes exhibit high gradient but low hilltop curvature in the metavolcanics relative to theoretical predictions for steady state hillslopes. However, hillslopes in the granodiorite have, for the most part, variation in hilltop curvature, hillslope length and hillslope relief similar to model predictions for steady state hillslopes. The curvature of hilltops adjacent to main stem channels implies that the coefficient of sediment transport is two times larger in the granodiorite (c. 8.8 m2 ka-1) than in the metavolcanics (c. 4.8 m2 ka-1). The data suggest that hillslopes get shorter as erosion rates increase due to the increased influence of debris flows in valley incision, suggesting that drainage density increases with erosion rate. The incision wave associated with more rapid erosion in the Feather River has propagated further into a basin developed on the metavolcanics and hence this substrate is less resistant to channel incision. I review an inventory of values for the transport coefficient for hillslope sediment transport but find that no clear patterns emerge with varying lithology. However in unconsolidated substrates, precipitation may play an important role in modulating sediment transport through variation in rain splash impact frequency and the frequency of wetting/drying, freeze/thaw, and expansion/contraction cycles. Finally I apply the same techniques to study hillslope morphology to a landscape where the tectonic history has a documented influence on landscape development. The Dragon’s Back pressure ridge, Carrizo Plain, CA, consists of a series of small catchments adjacent to the San Andreas fault, where previous detailed geologic mapping has allowed the spatial and temporal distribution of uplift to be constrained. This landscape offers a hitherto unique opportunity to study the temporal evolution of hillslope morphology via ergodic substitution. I show that the time evolution of a sensitive indicator of erosion rate, hilltop curvature, can be predicted using a nonlinear sediment flux law. Further to this, the temporal evolution of relief and hilltop curvature experiences hysteresis as the landscape grows and decays. Relative to steady-state predictions, hillslope morphologies exhibit higher than expected values for relief during active uplift or landscape growth, and lower than expected relief during landscape decay. Therefore landscapes growing due to fault activity can be distinguished from those with quiescent faults undergoing topographic decay.
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Jamieson, Stewart S. R. "Modelling landscape evolution under ice sheets." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/29818.
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This thesis details the application of numerical modelling techniques to simulate erosion under ice sheets with the aim of better understanding the interrelationships between glacial erosion, long-term landscape evolution and ice dynamics. A model is developed that predicts patterns of basal erosion in a glaciologically sensible manner and shows that ‘fluvial’ landscapes can become ‘glacial’ systems within 100 kyrs. By simulating ice sheet growth and erosion over synthetic landscapes of varying form, amplitude and wavelength the topographic characteristics that are most critical to the evolution of ice dynamics and to ongoing erosion are identified. The model is applied to the solution of two puzzles regarding the interaction of ice, erosion and landscape in Patagonia and Antarctica. In settings similar to Patagonia, glacial erosion is shown to be able to drive large-scale change in ice dynamics on 105 to 106 year timescales. This goes some way to explaining the behaviour of the Patagonian ice sheet since the ‘Greatest Patagonian Glaciation’, whereby ice extents reduce over successive glacial cycles, contradicting patterns of global ice volume. In Antarctica, the model is used to predict the pattern of long-term ice mass expansion and associated patterns of landscape evolution. For the first time, predictions tied to ice dynamics are made regarding the degree to which the Antarctica landscape has been modified by ice as it expands from local to regional ice centres and then to a continental scale ice sheet. Common themes throughout this thesis are that pre-glacial landscape geometry is a critical driver of the pattern of landscape evolution under ice, and that erosion should no longer be considered a passive component of any glacial system over timescales of 105 and greater.
4
Boardman, John. "Landscape evolution over Pleistocene and modern timescales." Thesis, Keele University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400115.
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Bosch, Rachel. "Landscape Evolution of the Central Kentucky Karst." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627665906577779.
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Odoni, Nicholas Alan. "Exploring equifinality in a landscape evolution model." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/153687/.
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Model equifinality is the property by which very similar model outputs can be generated by many different combinations of model inputs. It is known in numerical models used in other disciplines, and is thought to be likely in landscape evolution models (“LEMs”) also, as they incorporate many process parameters of uncertain value. LEM equifinality, if pervasive, would be a serious obstacle to falsifying working hypotheses and would frustrate landscape evolution research, but to date it has not been quantified. This is attempted here, by sampling a LEM’s response in its parameter space. A well known LEM (‘GOLEM’, Tucker & Slingerland, 1994), used here as an exemplar, is applied to evolution of a c. 38 km2, 4th order catchment in the Oregon Coast Range. Ten of GOLEM’s parameters are selected for variation, covering mass movement, channel formation, fluvial erosion and weathering processes, and value ranges appropriate for the catchment are established from published data and calibration. Parameter space sampling is then carried out using a response surface methodology approach which reduces by c. 3 orders of magnitude the simulation run size needed to explore the 10-D parameter space. Initial simulations are run sampling the space according to a central composite design of 149 targeted parameter value combinations, which afford estimation of all parameter main and two-way interaction effects. Model outputs at 100,000 years are summarised by four metrics (sediment yield, drainage density, sediment delivery ratio, and a topographic metric), which serve as landscape descriptors. Equations, or “metamodels”, are derived by regression to describe each metric as a function of the GOLEM parameters, and further simulations allow testing and improvement of model fits (R2 of c. 98% for the sediment yield, drainage density and sediment delivery ratio, and c. 92% for the topographic metric). The parameter space is then sampled rapidly and densely (>>106 times), using each metamodel to predict GOLEM’s output at each sample point. Results are compared with a reference value for each metric, to obtain equifinal proportions in a range of permitted tolerance bands around the reference, and using a bootstrap to aid calculation of confidence intervals. The likelihood of obtaining an equifinal result is found to depend on the tolerance band and the metric e.g. the equifinal probabilities for drainage density are estimated to be c. 26% and 58% respectively in the 2% and 5% tolerance bands, compared with c. 68% and 99% for the sediment delivery ratio in the same bands. Where combinations of metrics are used, the polymetric equifinal probability is often lower (and never higher) than it would be for any of the component metrics used singly. Also, the equifinal probability for any metric and tolerance band usually decreases as the number of parameters employed in the model increases. More generally, equifinal probabilities are seen to result from the combinations of parameter main effects and interactions driving each metric, thus allowing equifinality to be explored through the use of metamodel archetypes. Further research using other LEMs is needed, and the response surface methodology is recommended for both its computational efficiency and clarity in this respect.
7
Nicholson, Uisdean A. M. "Landscape evolution and sediment routing across a strike-slip plate boundary." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources. Restricted: no access until July 20, 2014, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59100.
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Baran, Ramona. "Quantification of landscape evolution on multiple time-scales." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-148038.
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9
CARBONO, ALONSO JOAQUIN JUVINAO. "COMPUTER SIMULATION OF LANDSCAPE EVOLUTION OF DRAINAGE BASINS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21617@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA superfície da terra é formada por processos geológicos que geram as rochas, assim como por processos naturais de degradação e de erosão. A erosão destrói as estruturas que compõem o solo e seu transporte é feito pela ação da água da chuva, do vento, da gravidade e até do gelo. A origem e evolução das bacias sedimentares, dentre outros fenômenos, é estudada pela geologia sedimentar, a qual trata do estudo dos processos físicos, químicos e biológicos atuantes na superfície da terra desde o seu início até os dias atuais. Na atualidade, o uso de modelos que permitem analisar processos de escoamento superficial, desprendimento de partículas e de transporte e deposição de sedimentos em bacias hidrográficas é cada vez mais frequente. O uso e análise desses modelos demonstra que, para escalas relativamente pequenas e áreas não muito extensas, o rebaixamento do perfil dos rios está diretamente ligado aos processos de deformação tectônica. Por outro lado, modelos de previsão de evolução do relevo associados com intemperismo, erosão e deposição de sedimentos, considerando escalas espaciais do tipo regional ou continental e escalas de tempo relativamente grandes (maior que 10(5) anos) devem ser desenvolvidos acoplando tanto efeitos tectônicos como morfológicos. Neste trabalho é apresentado um modelo computacional que permite analisar a evolução na mudança do relevo de bacias hidrográficas, em pequena e grande escala, assim como estimar a produção de sedimento resultante do processo erosivo. O algoritmo de análise é escrito na linguagem de programação Cmais mais e considera a simulação de diferentes cenários, que incluem deformação tectônica, processos de encosta (difusão e movimentos de massa) e processos de incisão fluvial, dando-se particular atenção à formação e evolução da rede fluvial de drenagem. Para a análise de resultados, o programa oferece a visualização 3D de diferentes superfícies: distribuição dos sedimentos, evolução da rede fluvial, mudanças topográficas do relevo, etc.
The surface of the earth is formed by geological processes that originate the rocks, as well as for natural processes of degradation and erosion. The erosion destroys the soil structures and the transport of sediments is made by the action of the rain water, wind, gravity and, in some cases, ice. The origin and evolution of sedimentary basins, amongst other phenomena, are studied by the sedimentary geology, which deals with the analysis of physical, chemical and biological processes that act directly on earth surface since its origin until the current days. Nowadays, the use of runoff - erosion models that analyze processes such as detachment of particles and transport and deposition of sediment in drainage basins is every time more frequent. The use of these models demonstrates that, for relatively small scales and not very extensive areas, relief changes are directly related to tectonic processes. On the other hand, landscape evolution models and associated weathering, erosion and deposition with parameterization for regional or continental spatial scales and large time scales (more than 10(5) years), must be developed to adequately couple tectonics and geomorphology. Is presented in this work a computational model to analyze the landscape evolution in hydrographic basins, considering small and large scales, as well as evaluate the production of sediment resultant of the erosive process. The algorithm is written in the programming language C++ and considers the simulation of different scenes, that include tectonics, hillslope processes (diffusion and landslides) and bedrock incision, giving particular attention to the channel network evolution. For the analysis process the program offers the visualization of different 3D surfaces: sediment distribution, drainage network, topographical relieves etc.
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Richardson, Paul William Ph D. Massachusetts Institute of Technology. "Topographic asymmetry and climate controls on landscape evolution." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101346.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 145-157).
Landscapes are expected to evolve differently under the influence of different climate conditions. However, the relationship between landscape evolution and climate is not well understood. I investigate the relationship between landscape evolution and climate by using natural experiments in which climate varies with slope aspect (geographic orientation) and causes differences in landscape form, such as steeper equator- or pole-facing slopes. In order to understand which mechanisms are responsible for the development of this topographic asymmetry, I adapted a numerical landscape evolution model to include different asymmetry-forming mechanisms such as aspect-induced variations in soil creep intensity, regolith strength, and runoff, and also lateral channel migration. Numerical experiments reveal topographic signatures associated with each of these mechanisms that can be compared with field sites that exhibit asymmetry. I used these numerical model results, along with estimates of field-saturated hydraulic conductivity, soil strength, evidence of stream capture and channel beheadings, and erosion rates determined from cosmogenic radionuclides to determine which asymmetry forming mechanisms are likely responsible for the topographic asymmetry at Gabilan Mesa, a landscape in the central California Coast Ranges. I find that aspect-dependent differences in runoff are most likely responsible for the bulk of the asymmetry at Gabilan Mesa, but lateral channel migration has contributed to the asymmetry in some locations. To further investigate climate's influence on landscape evolution, I compiled new and previously published estimates of slope-dependent soil transport efficiency across a range of climates. I find that soil transport efficiency increases with mean annual precipitation and the aridity index, a measure that describes water availability for plants. I also find that soil transport efficiency varies with lithology and that different measurement techniques can bias estimates of the soil transport coefficient.
by Paul William Richardson.
Ph. D.
11
SoÌlyom, PeÌter. "The effect of flow path geometry on landscape evolution." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422439.
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Foster, David. "Landscape Evolution in the Northern Basin and Range, USA." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503647.
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McLaughlin, Win. "Landscape and Biotic Evolution of the Kochkor Basin, Kyrgyzstan." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23810.
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Kyrgyzstan is the single most seismically active country in the world. Accessing the past, and therefore future hazard of faults, necessitates a high-resolution understanding of the timing of different geologic events. With no radiometrically datable rocks from the Neogene of Kyrgyzstan, I herein present the first work formally describing Neogene vertebrate faunas from the Kochkor Basin of Kyrgyzstan. I utilize a combination of biostratigraphy and magnetostratigraphy to constrain the timing of when the vertebrate assemblages were emplaced, and have dated the three bone beds to all fall in the latest Miocene, spanning 9-5 million years ago. All four bone beds represent mass death assemblages, inferred to be from drought-caused mortality. The timing of the deposits corresponds to uplift in the Pamirs, Himalayan, and greater Tibetan Plateau, which would have blocked the Indian monsoon from reaching Central Asia, forever altering the climate and biota of the region. This change is reflected in the shifting mammals faunas, as evidenced by the novel rhinocerotid I describe in a phylogeographic context.
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Spry, Melissa J., and n/a. "The Regolith and landscape evolution of a low relief landscape: Cobar, Central New South Wales, Australia." University of Canberra. Resource, Environmental & Heritage Management, 2003. http://erl.canberra.edu.au./public/adt-AUC20050704.162445.
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Construction of a 1:250,000 scale regolith-landform map of the Cobar area of central New
South Wales (NSW) Australia, demonstrates the presence of a wide range of previously undescribed
regolith materials, landforms and landscape features in the region. The map covers the east-west extent
of the Cobar Basin, extends to the west onto the Darling River Floodplain, and east onto rocks of the
Girilambone Group. The mapping area is centred on the Cobar township and covers -14,730 krn2
between 303113 and 446113 E and 6483184 and 6586183 N (AGO 66, MGA Zone 55). 48 regolithlandform
units have been identified, including both transported (alluvial, colluvial, aeolian, lacustrine)
and in situ materials. A range of siliceous, ferruginous and calcareous indurated materials are also
present.
Four major drainage types have been identified based on lithological, sedimentological and
topographic differences in alluvial materials. The 4 drainage types include: 1) modern drainage; 2)
maghemite and quartzose gravels elevated 1-2 m relative to the modern drainage; 3) higher
topographically inverted, and at least partly silicified, gravels; and, 4) sediments of Cretaceous origin.
Multiple phases of drainage stability and instability from the Cretaceous to the present are indicated
within the sediments. Breaching of drainage divides and increased dissection of the modern drainage,
especially to the south of Cobar, indicate possible tectonic movement across a major regolith-landform
boundary in the southern map area. Colluvial materials are more widespread to the north of Cobar
reflecting the increased landscape dissection to the south. Colluvial fans are preserved adjacent to
major rangefronts. Aeolian and lacustrine materials include longitudinal dunefields of the Darling
River floodplain, source bordering dunes, and small lunettes associated with the Barnato Lakes system.
Regolith-landform mapping at Cobar has been used to assess the applicability of previously
developed landscape evolution models of the Cobar Block and surrounding region, and to develop a
new landscape evolution model for the region. The new landscape evolution model of Cobar indicates
minimal deposition of Cretaceous sediments, succeeded by high-energy early Tertiary fluvial regimes
across the Cobar landscape. Weathering and sediment deposition continued into the Miocene, coupled
with deep valley incision on the Cobar Block associated with early Oligocene regression. By the close
of the Miocene, the Cobar Block had eroded to predominantly bedrock terrain and widespread filling of
previously incised valleys occurred. A decrease in erosion and fluvial activity led to the formation of
the modern drainage during the Pliocene-early Quaternary, followed by the formation of alluvial,
aeolian and lacustrine deposits in the later Quaternary. Regionally, Eromanga Basin sediments were not
extensive over the Cobar Block, and low rates of erosion are recorded at Cobar from the Cretaceous to
the present. Former northerly drainage did exist in this area in the Cretaceous, but was limited in
distribution. By at least the Early Tertiary the Cobar area was a structural high and drainage systems of
the region had assumed their current configuration. These findings do not support interpretations of
AFTT data of significant cover and subsequent stripping over the Cobar Block in the Early Tertiary.
Evidence of landscape evolution from the Cretaceous to the present suggests that the Cobar
landscape has been responding to changes in the primary landscape forming factors of lithology,
climate and to a lesser degree, tectonics. Variations in the these three primary landscape forming
factors have contributed to ongoing weathering, relatively continuous deposition, and periods of
relative stability and instability, particularly in response to climatic and baselevel fluctuations, within a
dynamically evolving landscape throughout the entire Tertiary. Former landscape evolution models of
peneplanation and pediplanation, based on correlation of palaeosurfaces including duricrusts, a deep
weathering profile developed during extended planation in the Early Tertiary, and tectonism during the
late Tertiary in the Cobar area, are not supported by evidence preserved in regolith-landform features at
Cobar.
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Sharma, Milap Chand. "Quaternary history and landscape evolution of NW Garhwal, central Himalaya." Thesis, Royal Holloway, University of London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242051.
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Collins, Daniel B. G. (Daniel Benjamin Gardiner) 1976. "Modeling the effects of vegetation-erosion coupling on landscape evolution." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84316.
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Baker, Katie. "The chromatin landscape of barley : gene expression, evolution and epigenetics." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/13a096cd-f45b-4e34-babd-ccb3ff3607ca.
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Barley (Hordeum vulgare) is an economically important crop species with a large diploid genome. Around a half of the barley genome and a fifth of the genes are constrained within a low-recombining pericentromeric (LR-PC) region. I explored the LR-PC gene component with a genomic investigation of gene expression, diversity and evolution. Chromatin environments were also explored in the LR and high recombining (HR) regions by surveying the genic and genomic distributions of nine histone modifications. Firstly, regions of HR and LR were identified and compared for gene evolution, expression and diversity. LR regions of the barley genome were found to be restrictive for gene evolution and diversity, but not gene expression. I employed a bioinformatics approach to identify ancient gene pairs in barley to determine the long-term effects of residency in those regions upon gene evolution. Gene pair loss in LR regions was found to be elevated relative to the HR regions. Applying the same method to rice and Brachypodium distachyon revealed the same situation, suggesting a universal process in the grasses for loss of gene pairs in LR regions. The chromosomal distributions of transposable elements (TEs) were also explored and examined for correlations with recombination rate. Secondly, I developed a chromatin immunoprecipitation followed by Next Generation Sequencing (ChIP-seq) protocol for the investigation of histone modifications in barley seedlings. A protocol was optimised for the fixation, extraction and sonication of barley chromatin. The protocol was applied using antibodies against 13 different histone modifications. Following DNA library construction and Illumina sequencing, a bioinformatics pipeline was devised to analyse the sequence data. NGS reads were mapped to a custom assembly of the barley cultivar Morex reference genome sequence before peak calling. Genomic and genic locations were determined for the covalently modified histones. Four modifications were discarded from further study on the basis of low peak numbers or unexpected chromosomal locations. The remaining nine modifications were classified into four groups based on chromosomal distributions. Groupings were closely mirrored by peak sharing relationships between the modifications except histone H3 lysine-27 tri-methylation (H3K27me3). In addition, chromatin states representing local chromatin environments were defined in the barley genome using the peak sharing data. Mapping the states onto the genome revealed a striking chromatin structure of the gene-rich chromosome arms. A telomere-proximal region bearing high levels of H3K27me3-containing states was found adjacent to an interior gene-rich region characterised by active chromatin states lacking H3K27me3. The LTR retroelement-rich interior was found to be associated with repressive chromatin states. The histone modification status of TE classes were also probed revealing unexpected differences relating to the genomic and genic distributions of these elements. Finally, a genome browser was created to host the information publicly.
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Mo, Fei. "The evolution of the urban landscape of Shanghai (1843-1949)." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11585/.
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The character of a city derives in substantial part from buildings, groups of buildings and their associated open spaces. The nature of this relationship remains poorly understood in many cities. Previous studies have shown that the process of modernisation in Asian cities was significantly influenced by European and American practices and theories, although these often interacted with local traditions. From the 1840s, China came into the modern era, and the first treaty port Shanghai has become the key to understand the evolution of Chinese cities under inextricable modernisation, westernisation and urbanisation. This city has experienced drastic changes in its city character and urban environment since it first grew to prominence in the 1840s. and foreign concessions were venues that international notions and cultures encountered with Chinese traditions. This research is intened to uncover the contributions of international ideas and the rising Chinese nationalism to the evolution of urban landscapes in Shanghai from the 1840s to the mid 20th century. This is crucial to the international history of landscape development, as duiring this period, influential notions of city planning and landscape design shaped many cities in Europe, United States and Asia, but cases in China were rarely explored in previous studies. Specifically, this research explains the landscape evolution in terms of the ideology, type and design of open space, while relating these changes to their social usages. Primary data were collected from archives and libraries in China, the UK and the United States. This research examines the development of landscape at different scales, in order to reveal various drivers of the evolution from multiple aspects, and identify links between different developments. First, it investigates how international urban planning concepts were interpreted to fit the local context, and how they contributed to the evolving open space patterns of the city. Secondly, three aspects were selected for in-depth study: public gardens, parks and recreation grounds; the residential landscape of terraced housing, and private gardens. Thirdly, this research explores evolving attitudes to urban landscapes in the context of Chinese modernisation. This research concludes that the evolution of the urban landscape of Shanghai was mainly driven by International notions of urban planning and landscape design, rising Chinese nationalism and substantive demands for varied types of open spaces and a better urban environment. The development in Shanghai cannot be understood locally, but should be read in the international context of urban development. The distinctive local character of the city was embodied in the availability, type and design of different types of open space, and the nature of the urban landscape in Shanghai is a consequence of the historical stages of its development and especially of its opening up to European and American ideas.
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Mackey, Benjamin Hunter. "The contribution of large, slow-moving landslides to landscape evolution." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10555.
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xvi, 136 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.This dissertation discusses the contribution of deep-seated landslides and earthflows to the morphology, erosion, and evolution of mountainous landscapes, focusing on the northern California Coast Ranges. In active landscapes, channel incision is necessary to create relief but also increases stresses in adjacent hillslopes, ultimately leading to slope failure. While conceptually simple, the spatial relationships between channel incision and landsliding have not been well quantified. Along the South Fork Eel River, I mapped the distribution of deep-seated landslides using light detection and ranging (LiDAR) derived maps. Landslide density increases in regions subject to late Pleistocene-Holocene channel incision and particularly in response to lateral incision at the apex of meander bends. Wavelet analysis of channel sinuosity reveals hillslopes are most sensitive to meander wavelengths of 1.5 km. Argillaceous lithology generates abundant earthflow activity along the main stem Eel River, yet spatial and temporal patterns of earthflow movement are poorly understood. I undertook a detailed study of the Kekawaka Earthflow using LiDAR, meteoric 10 Be in soil, orthorectified historical aerial photographs, and field surveys. Inventories of 10 Be in soil pits increase systematically downslope, indicate an average movement rate of 2.1 ± 1.3 m/a over the past 150 years, and establish a minimum earthflow age of 1700 years. The Kekawaka earthflow has a systematic history of movement, both spatially, with greatest movement in the narrow transport zone, and temporally, as velocities peaked in the 1960's and have slowed since 1981. I used LiDAR and aerial photographs to map earthflow movement and calculate sediment flux across 226 km 2 of the main stem Eel River. From 1944-2006, 7.3% of the study area was active, and earthflows account for an erosion rate of 0.53 ± 0.04 mm/a, over half the regional average sediment yield. Velocity time series on 17 earthflows suggest temporal earthflow behavior is influenced by decadal-scale changes in precipitation, temperature, and river discharge, although local topographic factors can overwhelm this climatic signal. When active, earthflows erode an order of magnitude faster than surrounding terrain; however, source supply limitations appear to govern long- term earthflow evolution. This dissertation includes previously published coauthored material.
Committee in charge: Joshua Roering, Chairperson, Geological Sciences; Ilya Bindeman, Member, Geological Sciences; Dean Livelybrooks, Member, Physics; Ray Weldon, Member, Geological Sciences; W. Andrew Marcus, Outside Member, Geography
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Anders, Matt D. "Quaternary Geology and Landscape Evolution of Eastern Grand Canyon, Arizona." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/6738.
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Tectonics and drainage evolution are controlling overall landscape incision in eastern Grand Canyon. Superimposed on downcutting are dynamic responses of hillslopes, tributary streams, and the Colorado River to glacial-interglacial climate cycles. Five tributary stream fill terraces have been identified, and luminescence dating indicates aggradation was occurring 50- 34 ka {S3), 12-7 ka (S2), and 5-3.5 ka (S1). Seven Colorado River fill terraces have been identified, and luminescence and U-series dating indicate deposition was occurring 343-322 ka (M5), 151-118 ka (M4), and 71-64 ka (M3). Aggradation by the Colorado River in eastern Grand Canyon begins during glacial advances and continues into the subsequent climate reversals. It appears to be driven by increases in sediment yield associated with glacial advances in headwater areas and glacial conditions elsewhere in the Colorado River drainage basin. Local catchments have buffered responses to climate change, with stream aggradation being driven by changes in sediment yield and hydrology of hillslopes. Tributary stream aggradation during full-glacial conditions (S3) is caused by a decrease in precipitation intensity and an increase in bedrock weathering. Aggradation during glacial-interglacial transitions (S2) and interglacial conditions (S1) is the result of increased erosion of older surficial deposits and decreases in vegetation cover. In the context of the current working model for the response of drylands to climate change, eastern Grand Canyon is distinct in that significant tributary stream aggradation occurs during full-glacial climate conditions and throughout the tributary drainage networks. This suggests that landscape response to climate change in semiarid environments may be slightly different than in arid settings. Bedrock incision by the Colorado River has been occurring at a rate of 0.13 mm/yr over middle-late Quaternary time. The technique used to make this calculation involves comparing snapshots of the river at analogous positions within its aggradation-incision cycles. The most accurate calculation results from tracing the elevation of the valley bottom through time. This method requires robust age control, but is advantageous because true bedrock incision is calculated and possible error associated with the use of short time intervals and thick fill deposits is eliminated.
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Fenwick, Helen. "The Lincolnshire marsh : landscape evolution, settlement development and the salt industry." Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:5669.
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The coastal wetland, known as the Lincolnshire Marsh, is investigated in order to understand the ways in which people in the past exploited coastal zones. This research into a previously neglected area has tested the validity of' Rippon's (2000) three-part model ofcoastal strategies - exploitation, modification and transformation. The Lincolnshire Marsh, as considered in this thesis, covers a region from Cleethorpes in the north to Wainfleet in the south. The study area also encompasses areas of the adjacent dry land, of the Middle Marsh and the Wolds, to the west. A wide range of data are studied to help build a picture of the methods people have used to settle this region, from earlier prehistory through to the sixteenth century. It has been shown that the strategies adopted have varied over space and time, and that the region cannot be viewed as a single developmental unit. Four separate development zones have been postulated. showing differences in the visible Bronze Age reactions to rising sea-levels; in the concentration of salt production to specific regions, in certain periods; in the place-name evidence; in the Domesday landholdings; and in the settlement pattern. Following Rippon's (2000) three-part model it has been shown that for the majority of its history, people have been happy to exploit the natural resources on offer along the Marsh, whether they be salt or the natural havens or pasture. Although salt was important in this development, it is limited in specific periods, to specific areas. On occasion the occupants of the Lincolnshire Marsh have modified the coast to aid with settlement and exploitation; however, there were no large-scale attempts at reclamation, or transformation until the sixteenth century. In this respect the region is significantly different from many other coastal wetlands in north-west Europe which see large-scale attempts at transformation by the thirteenth century at the latest. A subdivision has also been apparent at the modification stage - in some cases this strategy was intentionally adopted, in other areas the modification was accidental, a by-product of the salt industry.
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Sinclair, Kevin Michael. "Stream erosion and its relation to drainage networks and landscape evolution." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627590.
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Bäckman, Emma, and Josefin Ellmarker. "The Evolution of Scania: How the landscape grew with the industrialization." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-33357.
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It has been a constant fight for Scania between Sweden and Denmark, but in 1658 the landscape finally became Swedish. New technologies and innovations emerged with the industrial revolution and influenced Scania. The society developed and the standard of living was improved. The agriculture sector in Scania has always been strong because of the farmable land. From a geographical point of view, the landscape has a good location since it is connected to the Baltic Sea. This has contributed to good trading and communication possibilities, which is why Scania has been a desirable landscape. The industrial revolution contributed to the development of many societies, which resulted in economic growth in Scania.
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Peifer, Bezerra Daniel. "The pattern and style of landscape evolution in post-orogenic settings." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30680/.
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Chilton, Kristin Danielle. "Investigating the Effects of Lithology on Landscape Evolution Processes across Scales." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104740.
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Geomorphologists have long observed the influence of lithology on landscape form and evolution. However, the specific mechanisms by which this is accomplished are not well characterized. Here, I investigate the role of lithology in landscape evolution processes across spatial and temporal scales and geomorphic domains, to progress our understanding of the basic controls on the processes which shape Earth's surface. These investigations were carried out within the Valley and Ridge province of the Appalachian Mountains, where contrasts in strength of underlying lithologies (juxtaposed by Alleghanian deformation) exert a clear, dominant control on the fabric of the landscape, providing an excellent opportunity to study the influence of lithology on a variety of landscape evolution processes.
First, I assess the geomorphic function of boulders found on hillslopes and channels in the Valley and Ridge province of the Appalachians, which are sourced from resistant lithologies capping ridgelines. High-resolution UAV surveys and field mapping of boulder distributions and characteristics reveal that boulders are abundant on hillslopes and highly concentrated in channels, often trap sediment upslope, and appear to be long-lived. These observations suggest that boulders act as armor for hillslopes and channels, shielding weaker underlying units from erosion and inhibiting fluvial incision, and therefore play an important role in preserving topography in the Valley and Ridge landscape, highlighting a specific mechanism by which lithology exerts an influence on topography in this setting. Second, I investigate the relative importance of rock strength and discontinuity spacing in setting fluvial bedrock erodibility by comparing knickpoint and non-knickpoint bedrock, which correspond to end-member erodibility cases, and assess how lithology impacts knickpoint expression. Detailed field surveys of 21 lithologic knickpoints, surrounding non-knickpoint reaches, and corresponding bedrock properties reveal three key outcomes: 1) discontinuity spacing is a stronger predictor of knickpoint occurrence, and therefore more significant in setting bedrock erodibility in this setting, confirming quantitatively the hypothesis that discontinuities exert a dominant control on fluvial erodibility, 2) knickpoint expression is a function of the unique combination of characteristics within a given stratigraphic interval, and therefore highly complex and specific to local conditions, implying that knickpoint morphology should be interpreted with extreme caution, and 3) because all 21 study knickpoints occur within the same unit, inter-unit heterogeneity must be accounted for before lithologic influence on channel profile convexities can be ruled out, rather than comparing to geologic map contacts. These findings represent an important contribution towards a more functional understanding of the influence of lithology on fluvial bedrock incision processes.Doctor of Philosophy
It has long been observed that underlying geology has a strong impact on the shape of the surrounding landscape and influences the erosional processes that act within that landscape. However, though the importance of rock type in shaping landscapes is recognized, the specific mechanisms by which this is accomplished are not well understood. The work presented here investigates the role of rock type and rock properties in landscape evolution processes in both hillslope and river environments within the Valley and Ridge Province of the Appalachian Mountains. This setting is ideally suited for investigating the role of rock type on landscape evolution processes because of the wide variation in rock types present in this setting, which exert a strong influence on local topography (e.g., strong rocks form ridges while weak rocks underlie valleys). First, I mapped the distribution of large boulders on local Valley and Ridge slopes and mountain streams to assess the potential for these boulders to play a role in preserving local topography. Results show that boulders are sourced from resistant rock types found along ridgelines, and are abundant on hillslopes and highly concentrated in channels. Boulders also trap sediment upslope and appear to remain in place for long periods of time. These observations suggest boulders play an important role in slowing erosion of weaker rock types underlying hillslopes and channels, and therefore aid in preserving topography in this setting. Second, I conducted detailed surveys of local small-scale waterfalls and surrounding flat river reaches and compared properties of the bedrock between these locations to better understand how bedrock properties influence erodibility. In this setting, waterfalls often signify strong underlying bedrock relative to the rock beneath flat river reaches, so comparing bedrock properties between these areas should give insight into how properties like rock strength and bed thickness impact how erodible the bedrock is. Results show that bed thickness is the most important variable impacting bedrock erodibility in this setting, and that waterfall appearance is a product of the unique combination of bedrock properties within a given area. These results are important for improving our ability to model natural landscapes and erosional processes, and for developing a more complete understanding for the relationships between rock type and river morphology.
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Cerovski-Darriau, Corina. "Landslides and Landscape Evolution over Decades to Millennia—Using Tephrochronology, Air Photos, Lidar, and Geophysical Investigations to Reconstruct Past Landscapes." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20405.
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Landscapes respond to external perturbations over a variety of timescales, including million-year tectonic forcing, millennial to decadal climate fluctuations, and minutes-long high intensity storms or large magnitude earthquakes. In mountainous regions, understanding the role of landslides in driving the hillslope response to these perturbations is paramount for understanding landscape evolution over geologic timescales and hazards over human timescales. Here I analyze the landslide-driven hillslope response over millennial to decadal timescales using a variety of tools and techniques (e.g. tephrochronology, lidar and air photo analysis, field and subsurface investigations, and seismic refraction) in the Waipaoa Basin (New Zealand) and Oregon Coast Range (USA). For the Waipaoa study catchment, pervasive landslides have been sculpting >99% of the hillslopes in response to >50 m of fluvial incision following the shift to a warmer, wetter climate after the Last Glacial Maximum (LGM) (~18 ka). Then, starting in the late 1800s, European settlement resulted in deforestation and conversion of >90% of the landscape to pastureland—spurring a rapid increase in landslide-driven erosion. To quantify the landscape response, I first reconstruct LGM and younger paleosurfaces using tephrochronology and lidar-derived surface roughness to estimate the volume, timing, and distribution of hillslope destabilization. From these reconstructions, I calculate the post-LGM catchment-averaged erosion rate (1.6 mm/yr) and determine that the timing of the initial hillslope adjustment was rapid and occurred by ~10 ka. Second, I quantify the rate and volume of historic hillslope degradation using a 1956-2010 sequence of aerial photographs, lidar, and field reconnaissance to map the spatial extent of active landslides, create a ‘turf index’ based on the extent and style of pastoral ground disruption, correlate that with downslope velocity, and calculate the average annual sediment flux. From the sediment flux, I calculate an erosion rate over the past ~50 years (~20 mm/yr) that is 10x greater than post-LGM. Lastly, in Western Oregon, I confirm that seismic refraction can determine the size (e.g. depth) and failure style of landslides in western Oregon—data needed to incorporate these poorly studied landslides into future landscape evolution or hazard models.
This dissertation includes both previously published and unpublished co-authored material.
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Smith, Martin Lancaster, and martin smith@anu edu au. "Towards a Geochronology for Long-term Landscape Evolution, Northwestern New South Wales." The Australian National University. Research School of Earth Sciences, 2006. http://thesis.anu.edu.au./public/adt-ANU20061026.141414.
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The study area extends from west of the Great Divide to the Broken Hill and Tibooburra regions of far western New South Wales, encompassing several important mining districts that not only include the famous Broken Hill lodes (Pb-Zn-Ag), but also Parkes (Cu-Au), Peak Hill (Au), Cobar (Cu-Au-Zn) and White Cliffs (opal). The area is generally semi-arid to arid undulating to flat terrain covered by sparse vegetation.
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During the Cretaceous, an extensive sea retreated across vast plains, with rivers draining from the south and east. After the uplift of the Great Divide associated with opening of the Tasman Sea in the Late Cretaceous, drainage swung to the west, cutting across the Darling River Lineament. The Murray-Darling Basin depression developed as a depocentre during the Paleogene. Climates also underwent dramatic change during the Cenozoic, from warm-humid to cooler, more seasonal climates, to the arid conditions prevalent today. Up until now, there has been very little temporal constraint on the development of this landscape over this time period. This study seeks to address the timing of various weathering and landscape evolution events in northwestern New South Wales.
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The application of various regolith dating methods was undertaken. Palaeomagnetic dating, clay δ18O dating, (U+Th)/He and U-Pb dating were all investigated. Palaeomagnetic and clay dating methods have been well established in Australian regolith studies for the last 30 years. More recently, (U+Th)/He dating has been successfully trialled both overseas and in Australia. U-Pb dating of regolith materials has not been undertaken. Each method dates different regolith forming processes and materials. Palaeomagnetic and clay dating were both successfully carried out for sites across northwestern New South Wales, providing a multi-technique approach to resolving the timing of weathering events. Although (U+Th)/He dating was unsuccessful, there is scope for further refinement of the technique, and its application to regolith dating. U-Pb dating was also unsuccessfully applied to late-stage anatase, which is a cement in many Australian silcretes.
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Results from this study indicate that the landscape evolution and weathering history of northwestern New South Wales dates back at least 60 million years, probably 100 million years, and perhaps even as far back as 180 million years. The results imply that northwestern New South Wales was continuously sub-aerially exposed for the last 100 Ma, indicating that marine sedimentation in the Murray-Darling and Eromanga-Surat Basins was separated by this exposed region. The ages also provide further evidence for episodic deep chemical weathering under certain climatic conditions across the region, and add to the data from across Australia for similar events. In particular, the palaeomagnetic ages, which cluster at ~60 ± 10 Ma and 15 ± 10 Ma, are recorded in other palaeomagnetic dating studies of Australian regolith. The clay ages are more continuous across the field area, but show older clays in the Eromanga Basin sediments at White Cliffs and Lightning Ridge, Eocene clays in the Cobar region, and Oligocene Miocene clays in the Broken Hill region, indicating progressively younger clay formation from east to west across northwestern New South Wales, in broad agreement with previously published clay weathering ages from around Australia.
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These weathering ages can be reconciled with reconstructions of Australian climates from previously published work, which show a cooling trend over the last 40 Ma, following an extended period of high mean annual temperatures in the Paleocene and Eocene. In conjunction with this cooling, total precipitation decreased, and rainfall became more seasonal. The weathering ages fall within periods of wetness (clay formation), the onset of seasonal climate (clay formation and palaeomagnetic weathering ages) and the initiation of aridity in the late Miocene (palaeomagnetic weathering ages).
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This study provides initial weathering ages for northwestern New South Wales, and, a broad geochronology for the development of the landscape of the region. Building on the results of this study, there is much scope for further geochronological work in the region.
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Quigley, Mark Cameron. "Continental tectonics and landscape evolution in south-central Australia and southern Tibet /." Connect to thesis, 2006. http://eprints.unimelb.edu.au/archive/00002963.
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Schwanghart, Wolfgang [Verfasser]. "Climate and landscape evolution of the Ugii Nuur basin, Mongolia / Wolfgang Schwanghart." Berlin : Freie Universität Berlin, 2009. http://d-nb.info/1023463741/34.
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PINTO, RODRIGO WAGNER PAIXAO. "GEOMORPHOLOGICAL LANDSCAPE EVOLUTION OF THE GRANDE RIVER: DISSECTION DYNAMICS AND DRAINAGE CAPTURE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27097@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
A análise dos sistemas fluviais são de extrema importância na compreensão da evolução geomorfológica da paisagem, pois possuem características, seja no seu arranjo ou distribuição dos canais, que permitem elaborar os episódios que ocorreram ao longo do tempo. A quebra do continente Gondwana e seus múltiplos eventos até a consolidação do Rift Continental do Sudeste (RCS) implicou em uma mudança significativa no relevo sudeste e, consequentemente, nos sistemas de drenagens. Isto promoveu a reorganização dos sistemas de drenagens e uma nova dinâmica hidro-erosiva pelo rebaixado do nível de base na porção leste do continente com a consolidação do RCS. Diante do exposto, selecionou-se como estudo de caso a bacia do Rio Grande no Rio de Janeiro com o objetivo principal de entender o processo de evolução geomorfológica da bacia, a partir da organização da rede de drenagem e feições elementares da bacia frente aos eventos geológicos de formação e estruturação do substrato rochoso. A metodologia utilizada se baseia em trabalhos de gabinete, de campo e posterior análise dos dados gerados. Estes procedimentos visaram compreender a evolução do relevo na bacia do Rio Grande com base na correlação entre aspectos geológicos e geomorfológicos na organização do seu sistema fluvial. Pode-se inferir que a evolução geomorfológica da bacia do Rio Grande foi influenciada pelos múltiplos eventos tectônicos até a consolidação do RCS. Os dados demonstram forte controle do substrato rochoso na morfologia do relevo e na orientação da rede de drenagem. Os resultados das orientações dos fluxos de drenagem demonstram grande quantidade de rios nas orientações NE e NW. Acredita-se que a região correspondeu a um extenso planalto de altitude mais elevada que a atual, e sistema fluvial com direção predominante para noroeste/norte. A evolução da bacia do Rio Grande se deu através do avanço das drenagens atlânticas sobre o antigo Planalto Sudeste, através da erosão remontante e controladas pelo nível de base.
Analysis of river systems are very important in understanding the geomorphological evolution of the landscape because they have characteristics, either in your arrangement or distribution channels, which enable the development of the episodes that have occurred over time. The break of the Gondwana Continent and its many events to the consolidation of Southeast Continental Rift resulted in a significant change in Southeast relief and hence the drainage systems. This promoted the reorganization of drainage systems and a new hydro-erosive dynamic by lowered the base level in the eastern portion of the continent with the consolidation of the Cenozoic RCS. Given the above, it was selected as a case study the basin of the Grande River in Rio de Janeiro with the main objective to understand the process of geomorphological evolution of the basin, from the drainage network organization and basic features of the front basin to events geological formation and structure of the bedrock. The methodology is based on office work, field and subsequent analysis of the data generated. These procedures were aimed at understanding the evolution of relief in the Rio Grande basin based on the correlation between geological and geomorphological aspects of the organization of its river system. It can be inferred that the geomorphological evolution of the Grande River basin was influenced by multiple tectonic events to the consolidation of RCS. The data demonstrate strong control of bedrock in relief morphology and orientation of the drainage system. The results of the guidelines of drainage flows demonstrate large number of rivers in the NE and NW directions. It is believed that the region corresponded to an extensive plateau higher than the current altitude, and river system with predominant direction north-west / north. The evolution of the Rio Grande basin was through the advancement of the Atlantic drainages on the old Plateau Southeast, through remontant erosion and controlled by the basic level.
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Gasparini, Nicole M. (Nicole Marie) 1972. "Erosion and deposition of multiple grain sizes in a landscape evolution model." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/51560.
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Deal, Eric. "A Probabilistic Approach to Understanding the Influence of Rainfall on Landscape Evolution." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU012/document.
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Dans cette thèse je travaille sur la relation entre la pluviosité et l’érosion fluviatile en utilisant une approche probabiliste. Je développe une méthodologie indépendante de la moyenne pour caractériser la variabilité de la pluviosité journalière.L’indépendance vis-à-vis de la moyenne permet une comparaison simpleetobjectivedelavariabilitédelapluviosité sous différents régimes climatiques. Elle semontre également utile pour intégrer le concept de variabilité de la pluviosité dans lathéorie que je développe ensuite. J’applique cette approche à la chaine de montagnesHimalayenne en utilisant des données de pluviosité de hautes résolutions spatiale ettemporelle et trouve qu’il existe des variations significatives de la variabilité de la pluviositédans l’Himalaya. En prenant en compte la variabilité de la pluviosité en plusde la pluviosité moyenne, je trouve un lien entre pluviosité et érosion qui, d’un pointde vue géomorphologique, diffère, de façon significative, de celui déduit de la seulepluviosité moyenne.Ensuite, je développe une théorie d’érosion fluviatile du type ’puissance de flux‘ quicomprend une paramétrisation réaliste de la pluviosité et de l’hydrologie. Ceci estréalisé en intégrant un modèle hydrologique stochastique-mécaniste bien établi dansune formulation stochastique de la puissance de flux comprenant un seuil. La théoriehydrologique conduit à des expressions mathématiques pour la distribution et la variabilitédu débit journalier en fonction des conditions climatiques qui sont valablespour la majorité des régimes de débit observés à la surface de la Terre. Les nouveauxparamètres qui en découlent ont une signification bien ancrée dans des théories climatiqueet hydrologique établies et se mesurent facilement. Cette approche nous permetde prédire comment le taux d’érosion fluviatile répond à des changements du forçageclimatique. Je trouve ainsi que les processus hydrologiques peuvent avoir une influencesignificative sur l’efficacité érosive d’un forçage climatique donné. Cette approchepeut également être utilisée comme fondement de nouveaux modèles d’évolution desreliefs qui prennent en compte des conditions aux limites climatique et hydrologique.Une des principales conséquences d’intégrer l’hydrologie dans le modèle de puissancede flux est de révéler le double effet de la moyenne et de la variabilité du forçage climatiquesur la réponse écohydrologique. Une corrélation négative existe entre la moyenneet la variabilité qui restreint grandement les réponses possibles d’un bassin versant àdes changements climatiques. L’approche théorique que j’ai développée décrit égalementles relations qui relient la variabilité journalière à plusieurs paramètres écohydroclimatiques.Je trouve ainsi que l’index d’aridité, le temps de réponse du bassin versant,et l’épaisseur effective de sol sont les contrôles les plus importants sur la variabilité dudébit. Ceci a d’importantes conséquences pour le rôle que jouent l’hydrologie et lavégétation sur l’évolution des reliefs.Finalement, je démontre que l’influence de la variabilité journalière du forçage climatiquesur le taux d’érosion des rivières est principalement déterminée par l’existence et la valeur de seuils d’érosion. Je démontre que, quelques soient les détails du processus d’érosion considéré, c’est le rapport entre la valeur du seuil et la valeur moyenne du forçage climatique qui détermine si la variabilité compte ou pas, et dans quel sens.Parmi de nombreuses autres applications, ces découvertes contribuent à l’élaborationd’un nouveau cadre permettant de comprendre et prédire la réponse de la surface dela Terre à des changements de la moyenne et de la variabilité de la pluviosité et du débit des rivières. La généralité de ces découvertes a d’importantes implications pour le reste des travaux présentés dans la thèse, ainsi que pour les travaux antécédents sur le rôle de la variabilité de la pluviosité et du débit sur l’efficacité érosive des rivièresIn this thesis, we address the problem of how climate drives landscape evolution. Specifically, we work on the relationship between rainfall and fluvial erosion using a probabilistic approach. First we develop a mean-independent methodology to characterize the variability of daily rainfall. The mean-independent nature allows for simple, objective comparison of rainfall variability in climatically different regions. It also proves useful for integrating the concept of rainfall variability into theory. We apply this method over the Himalayan orogen using high spatial and temporal resolution rainfall data sets and find significant variations in rainfall variability over the Himalayan orogen. By taking into account variability of rainfall in addition to mean rainfall rate, we find a pattern of rainfall that, from a geomorphological perspective, is significantly different from mean rainfall rate alone. Next we develop of theory of stream power fluvial erosion that allows for realistically parameterized rainfall and hydrology. This is accomplished by integrating an established stochastic-mechanistic model of hydrology into a threshold-stochastic formulation of stream power. The hydrological theory provides equations for the daily streamflow distribution and variability as a function of climatic boundary conditions that are applicable across most of the observed range of streamflow regimes on Earth. The new parameters introduced are rooted firmly in established climatic and hydrological theory and are easily measured. This framework allows us to predict how fluvial erosion rates respond to changes in realistic rainfall forcing. We find that hydrological processes can have a significant influence on how erosive a particular climatic forcing will be. This framework can be used as a foundation for landscape evolution models that have realistic climatic and hydrological boundary conditions. One of the main strengths of integrating hydrology into the stream power model is to reveal the dependence of both streamflow mean and variability on the climatic forcing and ecohydrological response. This negative correlation of the mean and variability vastly restricts the likely responses of a river basin to changing climate. Our theoretical framework also describes the scaling daily variability with several other ecohydroclimatic parameters. We find that the aridity index, the basin response time, and the effective soil depth are the most important controls on discharge variability. This has important implications for the role of hydrology and vegetation in landscape evolution. Finally, we demonstrate that the way the Earth's surface responds to short-term climatic forcing variability is primarily determined by the existence and magnitude of erosional thresholds. We show that, irrespective of the nature of the erosional process, it is the ratio between the threshold magnitude and the mean magnitude of climatic forcing that determines whether variability matters or not and in which way. Among many other implications, our findings help provide a general framework to understand and predict the response of the Earth's surface to changes in mean and variability of rainfall and river discharge. The generality of this finding has important implications for the other work in this thesis, as well as previous work on role of rainfall and discharge variability on fluvial erosion
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Jackson, Eric Alan. "Towards a Prediction of Landscape Evolution from Chemical Weathering and Soil Production." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1516116071724445.
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Ebert, Karin. "Cenozoic landscape evolution in northern Sweden : geomorphological interpretation within a GIS-framework /." Stockholm : Department of Physical Geography and Quaternary Geology, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-30711.
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Diss. (sammanfattning) Stockholm : Stockholms universitet, 2009.At the time of the doctoral defence, the following papers were unpublished and had a status as follows: Paper 2: In press. Paper 3: Manuscript. Paper 4: Manuscript. Härtill 4 uppsatser.
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Marshall, Jill. "Lithologic, Climatic, and Biotic vs. Abiotic Controls on Erosion and Landscape Evolution." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/19291.
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The triumvirate of tectonics, lithology, and climate control landscape evolution. This study quantifies how lithologic variation and climate-mediated changes in ecosystems perturb steady state processes in the unglaciated, soil-mantled Oregon Coast Range (OCR). I first demonstrate that minor grain-scale differences in rock properties in a seemingly uniform sandstone control differences in rock strength, biotic bedrock-to-soil production efficacy, and erosion rates and influence relief at the watershed scale. I then build on sedimentology, paleoecology, and isotopic-derived paleoerosion data I collected from a new 50 ka sediment archive at Little Lake, OR to explore climate controls on soil production and erosion rates 21 ka across the OCR and spanning 50 ky within a single watershed. In Chapter III, I combine a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction and paleovegetation data to demonstrate that accelerated frost-driven erosion was pervasive across the OCR during the LGM. My findings provide a new framework to quantify how the late Pleistocene affects modern erosion and soil formation rates in unglaciated environments and implies that most landscapes reside in a transient state. In Chapter IV, I document climate-mediated ecosystem influence on erosion rates over 3 climatic intervals. 10Be-derived erosion rates increase 3x (from 0.6 mm/yr to 0.21 mm/yr) as the OCR transitioned from the open forest-dominated marine isotope stage (MIS) climate interval (50-26 ka) into the periglacial subalpine MIS 2 glacial interval (26-13 ka). Measured erosion rates fell by more than half as the subalpine ecosystem gave way to the modern MIS 1 closed canopy Douglas-fir forest. Coupling paleovegetation-derived climate information with core observations I model frost weathering intensity from ~ 43 ka to 21 ka and establish a correspondence with increasing frost weathering intensity and increasing 10Be-derived erosion rates. Utilizing a transient mixing depth and erosion rate model, I am able to broadly replicate measured erosion rates at Little Lake through time. My findings contradict previous work that suggests climate has only weak control on erosion rates.
This dissertation includes previously published and unpublished co-authored material.
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Mauch, James P. "Quaternary Incision, Salt Tectonism, and Landscape Evolution of Moab-Spanish Valley, Utah." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7068.
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To study the history of processes that shape the Earth’s surface, geologists look for markers in the landscape that they can date and use to measure change. Rivers leave such markers in their deposits and terrace landforms and in the overall shape of their elevation profile from head to toe. This thesis uses luminescence and cosmogenic methods to date the sediment in terraces to determine when the river deposited it. Field mapping and global positioning system (GPS) surveying are also used to measure the distance between terrace levels to quantify how much change has occurred. This study seeks to answer questions about when, how quickly, and why streams near Moab in Utah’s Canyonlands region have incised into bedrock. It seeks also to determine the history, rates, and patterns of the active and incremental sinking of Moab and Spanish valleys.
The results from this work show that the incision of canyons along Mill and Pack creeks upstream from Moab accelerated around 200,000 years ago to between 0.44 and 0.62 millimeters per year (mm/yr). The sinking of Moab and Spanish valleys also appears to have quickened around the same time and has occurred at up to 1.35 mm/yr in Moab Valley and around 0.45 mm/yr in Spanish Valley over the last 100,000 years. The Kayenta Heights fault zone (KHFZ) accommodates part of the sinking of Moab Valley and has slipped at an average rate of 0.44 mm/yr in the last 100,000 years. This study’s mapping of the length and width of individual fault strands supports prior interpretations that the KHFZ does not pose an earthquake hazard, though it can still be expected to produce active rock fall and rupture the ground surface locally.
That the sinking of Moab and Spanish valleys and the down-cutting of the upstream canyons has occurred at similar rates, and may indeed have sped up at a similar time in the past, indicates a linkage of the two processes. This is consistent with an existing hypothesis that Moab and Spanish valleys are sinking because groundwater is dissolving the buried salt deposits and transporting them out through the Colorado River. This process is able to continue because as the Colorado River and its tributaries incise lower into the landscape, groundwater follows and can reach greater depths in the salt deposits. The results of this study paint a picture of the recent and accelerated sinking of Moab and Spanish valleys, which has occurred jointly with incision of the regional drainage network. This acceleration of incision, which has been documented throughout the Canyonlands region, may relate to the Colorado River’s carving of Grand Canyon around 6 million years ago or may have come from a more recent and unknown downstream source.
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Smith, Martin Lancaster. "Towards a geochronology for long-term landscape evolution, Northwestern New South Wales /." View thesis entry in Australian Digital Theses Program, 2006. http://thesis.anu.edu.au/public/adt-ANU20061026.141414/index.html.
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Farrant, Andrew Roger. "Long-term Quaternary chronologies from cave deposits." Thesis, University of Bristol, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294897.
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Lopes, Ana Muller. "Transformações na paisagem rural do norte de Portugal." Master's thesis, ISA/UTL, 2011. http://hdl.handle.net/10400.5/4132.
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Mestrado em Arquitectura Paisagista - Instituto Superior de AgronomiaThe Landscape is a fluid and dynamic system that reflects the interaction between its ecological com-ponent and human activity. To speak about Landscape is therefore to speak about nature and human culture. The importance of the evolution of the agricultural and pastoral activities in the shaping of the Landscape, specifically in the North of Portugal, together with the structural role played by the me-thods of appropriation of agricultural territory, are the subject of this thesis. Having recognized the contribution of the political and economical history of Portugal in transforming the Landscape, and accepting that the changes effected upon the traditional landscape set-up have, not only, played an important role in the deterioration of the entire ecosystem, but also, contributed to the country’s dependence in food imports; it is intended to define the basis for obtaining a model for the organization of the Landscape that is sustainable from an environmental, socio-political and eco-nomical perspective. Through the proposal of a landscape plan for the municipality of Santo Tirso, the presented case study seeks to apply this concept of design and management of the landscape with the objective to reverse the downward trend of the heterogenic and complex layout of the landscape by applying the principles of the Landscape-System methodology (Magalhães et al, 2007).
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Pina, Carolina do Vale e. "Projectos de arquitectura paisagista no âmbito de planos de gestão de paisagens culturais. Caso de estudo: o acesso da Tapada da Ajuda ao Pólo Universitário da Ajuda." Master's thesis, ISA/UTL, 2011. http://hdl.handle.net/10400.5/4178.
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Mestrado em Arquitectura Paisagista - Instituto Superior de AgronomiaThe present work is a study about the Tapada da Ajuda and the importance of management plans on landscapes of cultural and patrimonial value like this one. There is also made a proposal of landscape intervention on the acess of the Tapada to the Pólo Universitário da Ajuda. The first chapter is an analysis of the international legal instruments that protects the patrimony, including the landscape heritage. Concerning the national legislation, there are legal means and institutions that protect the landscape heritage in Portugal. In the second and third chapters there is a synthetic description of the history of the Tapada, as well as its biophysical analysis and main elements. The fourth chapter is about the description of the factors that contributed to the landscape evolution of the Tapada and the proposal of a preliminary management plan that allows a more sustainable use of this cultural asset. The fifth and last chapter is dedicated to a proposal of landscape intervention on the acess of the Tapada to the Pólo Universitário da Ajuda.
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Prosser, Lee. "The Keynsham Hundred : a study of the evolution of a North Somerset estate, 350-1550." Thesis, University of Bristol, 1995. http://hdl.handle.net/1983/379582ef-cf43-41d6-94a8-36261070fdf9.
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Burg, Joel G. "Exploring the Role of the Artifact: An Evolution of Form, Function and Memory in the Urban Landscape." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23255.
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The urban landscape is a diverse environment that is constantly evolving. Such change does not remove and replace all of the remnants of the city\'s past, however, and the remaining artifacts become key pieces of local identity as a result of their persistence. Even so, artifacts are also complex entities and their definition and value can be drastically different given the context in which they exist. Nonetheless, artifacts can be broadly understood as interactive elements in the urban landscape that become enmeshed in their surrounding community, and serve a vital role as a result. This enquiry examines that role of artifacts in the urban landscape and seeks to uncover how such a role can inform effective design practice into the future.Master of Landscape Architecture
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Morrison, Erin Seidler, and Erin Seidler Morrison. "Exploring the Deterministic Landscape of Evolution: An Example with Carotenoid Diversification in Birds." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624290.
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Establishing metrics of diversification can calibrate the observed scope of diversity within a lineage and the potential for further phenotypic diversification. There are two potential ways to calibrate differences between phenotypes. The first metric is based on the structure of the network of direct and indirect connections between elements, such as the genes, proteins, enzymes and metabolites that underlie a phenotype. The second metric characterizes the dynamic properties that determine the strength of the interactions among elements, and influence which elements are the most likely to interact. Determining how the connectivity and strength of interactions between elements lead to specific phenotypic variations provides insight into the tempo and mode of observed evolutionary changes. In this dissertation, I proposed and tested hypotheses for how the structure and metabolic flux of a biochemical network delineate patterns of phenotypic variation.
I first examined the role of structural properties in shaping observed patterns of carotenoid diversification in avian plumage. I found that the diversification of species-specific carotenoid networks was predictable from the connectivity of the underlying metabolic network. The compounds with the most enzymatic reactions, that were part of the greatest number of distinct pathways, were more conserved across species’ networks than compounds associated with the fewest enzymatic reactions. These results established that compounds with the greatest connectivity act as hotspots for the diversification of pathways between species.
Next, I investigated how dynamic properties of biochemical networks influence patterns of phenotypic variation in the concentration and occurrence of compounds. Specifically, I examined if the rate of compound production, known as metabolic flux, is coordinated among compounds in relation to their structural properties. I developed predictions for how different distributions of flux could cause distinct diversification patterns in the concentrations and presence of compounds in a biochemical network.
I then tested the effect of metabolic network structure on the concentrations of carotenoids in the plumage of male house finches (Haemorhous mexicanus) from the same population. I assessed whether the structure of a network corresponds to a specific distribution of flux among compounds, or if flux is independent of network structure. I found that flux coevolves with network structure; concentrations of metabolically derived compounds depended on the number of reactions per compound. There were strong correlations between compound concentrations within a network structure, and the strengths of these correlations varied among structures. These findings suggest that changes in network structure, and not independent changes in flux, influence local adaptations in the concentrations of compounds.
Lastly, the influence of carotenoid network structure in the evolutionary diversification of compounds across species of birds depends on how the structure of the network itself evolves. To test whether the carotenoid metabolic network structure evolves in birds, I examined the patterns of carotenoid co-occurrence across ancestral and extant species. I found that the same groups of compounds are always gained or lost together even as lineages diverge further from each other. These findings establish that the diversification of carotenoids in birds is constrained by the structure of an ancestral network, and does not evolve independently within a lineage. Taken together, the results of this dissertation establish that local adaptations and the evolutionary diversification of carotenoid metabolism are qualitatively predictable from the structure of an ancestral enzymatic network, and this suggests there is significant structural determinism in phenotypic evolution.
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Jansson, Anna. "Stratigraphy, Landscape Evolution, and Past Environments at the Billy Big Spring Site, Montana." Thesis, The University of Arizona, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10643050.
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This thesis reconstructs the landscape evolution of the Billy Big Spring site (24GL304, Glacier County, north-central Montana) from the last glacial maximum to present through the analysis of sediment and soil samples collected from a transect of auger tests that bisected the site and surrounding landforms. Interpretations were drawn from stratigraphy, pedologic data, sedimentologic analysis and radiocarbon dating. The site landscape came into being in the late-Pleistocene, after Wisconsin-age glaciers retreated. Glacial retreat left a meltdown depression on the land that filled with water to form a pond, which persisted through the early-Holocene. The onset of the mid-Holocene (Altithermal) occurred before ~8,415 cal. yrs. BP, when increasingly arid conditions caused the water level to drop. The first radiocarbon dated human occupation of this site occurred during the Altithermal, ~7,030 cal. yrs. BP, after the eruption of Mount Mazama (~7,633 cal. yrs. BP). Arid conditions continued until ~7,000 cal. yrs. BP, when pond water re-expanded across the basin, marking the transition to the cooler late-Holocene. Sometime before 2,100 cal. yrs. BP, dry conditions returned, and the extent of the pond water decreased again. Since this time, overland alluvial processes have deposited sediments in the basin. Many hypotheses on how the Altithermal impacted the people of the Northwestern Plains have been proposed since the 1950s, but little agreement has been reached. This is due to the fact that there was great variation in how the Altithermal expressed itself throughout the Northwestern Plains. The human reactions to this phenomena cannot be explained simplistically for the region as a whole. This study shows that the Billy Big Spring site experienced drying during the Altithermal, but despite this, people continued to occupy this site. This evidence adds to the argument that the Altithermal climate of the Northwestern Plains did not have severe enough impacts to impose much hardship on its occupants.
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Jansson, Anna Maria, and Anna Maria Jansson. "Stratigraphy, Landscape Evolution, and Past Environments at the Billy Big Spring Site, Montana." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/626384.
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This thesis reconstructs the landscape evolution of the Billy Big Spring site (24GL304, Glacier County, north-central Montana) from the last glacial maximum to present through the analysis of sediment and soil samples collected from a transect of auger tests that bisected the site and surrounding landforms. Interpretations were drawn from stratigraphy, pedologic data, sedimentologic analysis and radiocarbon dating. The site landscape came into being in the late-Pleistocene, after Wisconsin-age glaciers retreated. Glacial retreat left a meltdown depression on the land that filled with water to form a pond, which persisted through the early-Holocene. The onset of the mid-Holocene (Altithermal) occurred before ~8,415 cal. yrs. BP, when increasingly arid conditions caused the water level to drop. The first radiocarbon dated human occupation of this site occurred during the Altithermal, ~7,030 cal. yrs. BP, after the eruption of Mount Mazama (~7,633 cal. yrs. BP). Arid conditions continued until ~7,000 cal. yrs. BP, when pond water re-expanded across the basin, marking the transition to the cooler late-Holocene. Sometime before 2,100 cal. yrs. BP, dry conditions returned, and the extent of the pond water decreased again. Since this time, overland alluvial processes have deposited sediments in the basin. Many hypotheses on how the Altithermal impacted the people of the Northwestern Plains have been proposed since the 1950s, but little agreement has been reached. This is due to the fact that there was great variation in how the Altithermal expressed itself throughout the Northwestern Plains. The human reactions to this phenomena cannot be explained simplistically for the region as a whole. This study shows that the Billy Big Spring site experienced drying during the Altithermal, but despite this, people continued to occupy this site. This evidence adds to the argument that the Altithermal climate of the Northwestern Plains did not have severe enough impacts to impose much hardship on its occupants.
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Falade, J. B. "Nigeria's urban open spaces : an inquiry into their evolution, planning and landscape qualities." Thesis, University of Edinburgh, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304191.
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Schaefer, Carlos Ernesto Reynaud. "Soils and paleosols from northeastern Roraima, north Amazonia : geomorphology, genesis and landscape evolution." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239746.
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Flores, Cervantes Javier Homero 1977. "Headcut retreat resulting from plunge pool erosion in a 3D landscape evolution model." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28361.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (p. 139-143).
Headcut retreat produced by plunge pools is represented using existing concepts about this type of erosion. The model estimates retreat rates, given flow, height of the headcut, upstream slope and Manning's roughness, and the relevant soil parameters (erodibility and critical shear stress). The model was analyzed to study its behavior as its input parameters changed, and its output was compared to experimental observations. Next, the plunge pool mechanism was implemented in an existing 3D landscape evolution model (CHILD) that includes other mechanisms of erosion like fluvial erosion and diffusion. The effects of headcut retreat on the landscape and of the landscape on the headcut retreat mechanism were investigated to learn what factors promote gully erosion and the extent of the impact of this type of erosion on the landscape. The results indicate that headcut retreat is most significant in zones comprising either gentle slopes or large headcut heights. Additional hydraulic conditions promoting to headcut retreat due to plunge pool erosion were found.
by Javier Homero Flores Cervantes.
S.M.
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Bradley, J. G. "Thermochronology, landscape evolution and hydrogeology of the Katonga Valley in south west Uganda." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1343834/.
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The reversed river systems of south west Uganda attracted geoscientists to study the geomorphology of the region in the mid 20th century. During the succeeding fifty years the population and GDP per capita have both risen between five and six fold with a consequent increase in water demand. This thesis aims to apply modern quantitative techniques and theoretical developments to improve our understanding of the landscape evolution of the Katonga Valley and contribute to the groundwater resource assessment of associated alluvial deposits. Karoo-age glaciogenic strata were discovered filling the western valley. Subsequent apatite fission track analyses reveal that the currently exposed rocks were reheated to a temperature consistent with over 2 km of burial during the Mesozoic. Therefore, it is inferred that the western River Katonga has preferentially eroded a Gondwanan paleovalley exhumed from beneath the former sedimentary cover. Electrical resistivity tomography of the valley fill has identified three broad cycles of erosion and deposition, including: 1) The Gondwanan palaeovalley with indurated glaciogenic strata; 2) The Neogene relict valley with fluviolacustrine sediments; and, 3) The late Quaternary channel and with recent wetland deposits. Downwarping of the Victoria Basin in the east produced the first drainage divide on the originally westward flowing River Katonga during the middle Pleistocene. Downthrow of the George Basin in the west led to rejuvenation of the western landscape prior to the formation of a second drainage divide due to rift flank uplift. Sand and gravel associated with an old denuded landscape survives in terraces above the water table in the central valley. Variable climate and fluctuating lake levels led to the deposition of fluviolacustrine deposits in the eastern valley. Pumping tests in this silty sand indicate that the transmissivity is almost always adequate for village water use and is sometimes commensurate with town water supplies.
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Lancaster, Stephen Thomas 1967. "A nonlinear river meandering model and its incorporation in a landscape evolution model." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/47672.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (p. 267-277).
A topographic steering river meandering (TSRM) model based on continuity of a simplified flow field through bends is developed. The equilibrium coupling between helical flow and sediment transport, as in Ikeda [1989] determines downstream variation of transverse bed slope. The model tests the hypothesis that meander development patterns can be captured under the assumptions: (a) bank shear stress arises from forces associated with topographically induced convective accelerations; (b) turbulent boundary layer dissipation of these forces at the banks is sufficiently represented by gaussian smoothing at a parameterized scale; and (c) lateral migration of the channel is proportional to bank shear stress. The resulting TSRM model produces realistic complex meander patterns and scroll bar-like topography. Model compound bend formation is compared to a field case and found to arise from the nonlinear interaction of bank roughness and channel hydraulics scales. When the latter is short relative to the former, maximum bank shear stress occurs early in the bend and leads to compound bend formation. New statistical stream sinuosity and spatial coordinate variation measures are applied to both natural and model streams and reveal secondary sinuosities arising from compound bend formation in both cases. Scroll bar topography and channel bank roughness are studied in the field to compare natural and model mechanisms. A channel-hillslope integrated landscape development (CHILD) model incorporates the TSRM model. The CHILD model represents the landscape as an irregular, Delaunay triangulated mesh of landscape nodes that may be moved, deleted, or added to accommodate meandering channels that are in general discretized at different spatial resolution than the surrounding landscape. The interactions among meandering, bank erodibility's bank height dependence, and uplift rate in a detachment-limited river valley are examined. An equilibrium landscape adjusts to the onset of meandering and approaches a new dynamic equilibrium. For the detachment-limited case, the hypothesis that meandering is more active when uplift is quiescent is rejected. When bank erodibility's bank height dependence is greater, bend scale sinuosity is smaller, but the tendency toward multi-bend loop formation is reinforced.
by Stephen Thomas Lancaster.
Ph.D.