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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Quaternary marine terraces on Cyprus : constraints on uplift and pedogenesis, and the geoarchaeology of Palaipafos

Zomeni, Zomenia 12 June 2012 (has links)
Numerous flights of Quaternary marine terraces are present around the island of Cyprus, in the Eastern Mediterranean. These terraces are a result of the global eustatic sea-level curve and local tectonism. Marine Isotope Stage (MIS) 5 through MIS 13 terraces are identified, mapped and dated. Palaeoshoreline elevation, an excellent indicator for a past sea–level, and new numerical geochronology are used to calculate an Upper Pleistocene uplift rate for various coastal sectors. Southwestern Cyprus presents the highest uplift rates of 0.35-0.65 mm/year with other sections suggesting uplift of 0.07-0.15 mm/year. This Upper Pleistocene tectonic signal is attributed to an active offshore subduction/collision system to the southwest of Cyprus, evidenced from the seismic activity offshore and the surface expression of a blind thrust fault in the Pafos region. Soil chronosequences and geology in southwestern Cyprus are studied in order to understand the Quaternary development on this uplifting landscape. Soil profile properties are used to calculate a profile development index (PDI), a method often applied to geomorphic surfaces as a relative dating method. Well-developed red and clayey soils occur in the coastal sector, on broad and low-angle surfaces, specifically on marine terraces and alluvial fans. Higher elevations of steep slopes consisting of carbonate and ophiolite lithologies host poorly developed soils. Results show variable PDI's on uplifted terraces, obscured by transported materials, active alluvial fan buildup and hillslope erosion. Calcium carbonate build-up in soil profiles in the form of nodular and laminar accumulations are used as another relative dating method. Geochronology of marine terraces is used as an age range approximation for carbonate stages. Geomorphologic mapping focuses on the southeastern part of the Pafos thrust fault, the only point on the landscape where this otherwise blind fault is exposed on the surface. This is the location of Palaipafos, an important Ancient polity, today the site of the village of Kouklia. Geoarchaeological study suggests little landscape change over the last 4000 years in the vicinity of the urban core of Palaipafos, this being attributed to bedrock and landscape resistance of its location, a plateau at 80 m amsl. Copper deposits in the Palaipafos hinterland had provided a valuable resource at one time. Soil and water resources continue to sustain agriculture.Tectonic uplift in this part of the Pafos thrust fault is estimated to be 2.1mm/year, considered, together with Late Holocene sea-level change responsible for the shifting locations and eventual abandonment of the Palaipafos harbor in the coastal lowlands. / Graduation date: 2013
22

The archaeology of the lower Sundays River Valley, Eastern Cape province, South Africa: an assessment of Earlier Stone Age alluvial terrace sites

Lotter, Matt Geoffrey 19 September 2016 (has links)
A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy Johannesburg, 2016 / The lower Sundays River Valley, within the Eastern Cape Province of South Africa, has featured in a range of papers over the last century. A large portion of these focuses on improving our understanding of a series of river terraces that border the present channel. Earlier Stone Age (ESA) artefacts were first noted to occur in these deposits in the 1950s, but since this initial research there has been no attempt to investigate these further. Our understanding of the Eastern Cape’s early archaeology is poor and this can be attributed to a lack of research. Only a single ESA site, Amanzi Springs, has been fully excavated for the entire province, and although the artefacts here provide some indication as to what characterises this region’s early archaeology, the significance of this site is limited by our inability to date it. Well-dated ESA sites are thus completely absent in the Eastern Cape. More recently, a study has provided a series of dates for the Sundays River terraces. Most importantly, this research confirmed the presence of these ESA – more specifically Acheulean – artefacts within three of these dated deposits, namely: Atmar Farm dated to 0.65 ± 0.12 Ma (millions of years ago), Bernol Farm dated to 1.14 ± 0.2 Ma, and Penhill Farm date to <1.37 ± 0.16 Ma and more recently constrained by this research to >0.485 ± 0.051 Ma. Accordingly, it has been the purpose of this research to investigate these deposits through both survey and excavation, and to provide details on this archaeology. This research thus provides the first ever comprehensively described and dated ESA sites for this region, and from this we can now begin to construct our understanding of the local Acheulean Tradition. This research also provides a contextual assessment for the formation of these deposits and what processes have influenced their formation and modification. Furthermore, from the detailed analysis of the artefacts, we can begin to understand the strategies employed in their production. Our investigations have shown that largely different contextual conditions are present at each of the three sites. This has had significant impacts on the integrity of these assemblages, and the preservation and retention of assemblage components are highly variable between them. All of the artefact assemblages show the following characteristics: simple strategies in core reduction, low levels of reduction in both cores and formal tools, simple and expedient production of retouched artefacts with little emphasis on careful edge modification, and large cutting tools (LCTs) that are flaked bifacially but have limited shaping overall. For the first time in half a century our research now provides comparative material from three dated sites that can be used to help understand variability in the local Acheulean Tradition. This has important implications for not only the Eastern Cape, but also to sites elsewhere in the interior. / MT2016
23

Percepção, recomendação e adoção do terraceamento agrícola comparadas ao seu funcionamento / Perception, recommendation and adoption of agricultural terracing compared to its operation

Franco, Alexandre Puglisi Barbosa 05 October 2018 (has links)
O desenvolvimento científico na área de conservação do solo teve pouco progresso nos últimos trinta anos. A utilização de modelos para prever a erosão do solo cujos resultados foram derivados de análises de dados de parcelas em países de climas temperados, não produziram os prometidos modelos que resolveriam as questões centrais da conservação do solo, e as questões ambiciosas foram trocadas pelas limitadas e fáceis de responder. Em virtude das mudanças tecnológicas na mecanização agrícola e o aumento do tráfego de máquinas nas áreas de produção, um novo cenário de conservação do solo aparece como base de uma reestruturação das recomendações de práticas conservacionistas. A ciência produz resultados com desasagem de tempo em relação à demanda do setor agrícola e as inovações e mudanças de manejo acabam sendo implantadas sem embasamento científico. Para entender a relação e a distância que existe entre as recomendações científicas e as práticas aplicadas no manejo agrícola na cana-de-açúcar no Estado de São Paulo um questionário foi aplicado em profissionais da área de conservação de três setores de atuação, setor de produção, setor público e comunidade científica. Os resultados mostraram que a aplicações de manejo e práticas de conservação do solo no Brasil estão fundamentadas em conhecimento popular oriundas de recomendações empíricas, simplificadas e generalizadas como uma receita única para uso em todas as condições edafoclimáticas. Há predominânica de práticas de infiltração implantadas de forma isolada sem dimensionamento adequado e adoção de práticas complementares e com negligência das práticas de drenagem. Devido ao grande número de casos de voçorocas causadas por falhas hidráulicas de terraços de infiltração nos últimos anos um experimento de campo foi implantado com objetivo de medir a variação da lâmina de água represada em canais de terraços de infiltração para determinar a taxa de infiltração de água. Foram determinadas as taxas de infiltração em doze terraços de infiltração. Os resultados do terraço 01, instalado em Latossolo Vermelho Amarelo Típico de textura média, mostraram ocupação do canal do terraço durante todo o período de avaliação e uma taxa de infiltração média de 0,79 mm h-1, com máxima de 1,83 mm h-1 e mínima de 0,17 mm h-1. O terraço 01 apresentou duas falhas hidráulicas com chuvas acumuladas de 6 dias acima de 90 mm. O terraço 02 instalado em Neossolo Quatzarênico Órtico, a taxa de infiltração foi de 0,87 mm h-1 em média, com valor máximo de 1,73 mm h-1 e mínimo de 0,26 mm h-1 e não apresentou falhas, entretanto outros terraços na mesma área apresentaram falhas com chuva acumulada de 5 dias que ultrapassaram os 90 mm. O terraço 03, em Latossolo Vermelho Típico de textura argilosa, apresentou taxa de infiltração média de 1,32 mm h-1, máxima de 2,66 mm h-1, e mínima de 0,21 mm h-1 e apresentou uma falha. Não foi possível determinar a taxa de infiltração de água no canal do terraço 04 em Nitossolo Típico, devido a inexistência de represamento de água durante todo o período. O terraço 05 instalado em Cambissolo Háplico textura argilosa imperfeitamente drenado apresentou três falhas e a maior taxa de ocupação da seção pelo maior tempo. Os terraços 06 e 07 em Latossolos de textura argilosa não foram ocupados com água proveniente de enxurrada por períodos que permitissem a leitura das réguas de medição, provavelmente pelas altas taxas de infiltração que não puderam ser determinadas. As réguas 08, 09 e 10, instaladas em Argissolo Vermelho Amarelo Típico de textura arenosa/média, foram monitorados no mesmo terraço, porém apresentaram resultados distintos apesar da proximidade. A taxa de infiltração da régua 08 foi em média de 0,65 mm h-1, máximo de 1,35 mm h-1 e mínimo de 0,21 mm h-1. A régua 09 apresentou média de 0,80 mm h-1, máximo de 1,67 mm h-1 e mínimo de 0,11 mm h-1, e apresentou um a falha hidráulica. O terraço 11, instalado em Argissolo Vermelho Amarelo Típico de textura média/argilosa apresentou taxa média de infiltração de 0,72 mm h-1, máximo de 1,82 mm h-1 e mínimo de 0,06 mm h-1, enquanto que o terraço 12, implantado no mesmo solo da régua 11, apresentou taxa média de 0,85 mm h-1, 2,14 mm h-1 de valor máximo e mínimo de 0,12 mm h-1. Os resultados evidenciaram que as taxas de infiltração de água no canal dos terraços na maioria dos casos são insuficientes para armazenar a quantidade de enxurrada produzida na área entre terraços e nas estradas próximas aos terraços. / The scientific development in soil conservation has made little progress in the last thirty years. The use of models to predict soil erosion based on results derived from plot data analyzes in temperate countries did not produce the promised models that would solve the central issues of soil conservation, and the ambitious issues were exchanged for the limited and easy to respond. Due to the technological changes in agricultural mechanization and the increase of machine traffic in production areas, a new soil conservation scenario appears as the basis for a restructuring of the recommendations of conservation practices. Science produces results with a time lag in relation to the demand of the agricultural sector and the innovations and changes of management end up being implanted without scientific base. In order to understand the relationship and the distance between the scientific recommendations and the practices applied in the agricultural management of sugarcane in the State of São Paulo, a questionnaire was applied to professionals in the conservation area of three sectors of activity, production sector , public sector and scientific community. The results showed that the management applications and soil conservation practices in Brazil are based on popular knowledge derived from empirical, simplified and generalized recommendations as a unique recipe for use in all soil and climatic conditions. There is a predominance of infiltration practices implanted in isolation without adequate sizing and adoption of complementary practices and with neglect of drainage practices. Due to the large number of gully cases caused by hydraulic failures of infiltration terraces in the last years a field experiment was deployed with the objective of measuring the variation of the retained water slide in channels of infiltration terraces to determine the rate of infiltration of water . Infiltration rates were determined on twelve infiltration terraces. The results of the terrace 01, installed in Typical Yellow Red Oxisol of medium texture, showed occupation of the terrace channel throughout the evaluation period and a mean infiltration rate of 0.79 mm h-1, with a maximum of 1.83 mm h-1 and minimum of 0.17 mm h-1. The terrace 01 had two hydraulic failures with accumulated rains of 6 days above 90 mm. The terrace 02 in Entisol Quartzipsamments, had an average infiltration rate of 0.87 mm h-1, with a maximum value of 1.73 mm h-1 and a minimum of 0.26 mm h-1, and showed no failures, although other terraces in the same had failures with cumulative rain of 5 days that exceeded 90 mm. In the typical Oxisol with clay texture, the terrace 03 had a mean infiltration rate of 1.32 mm h-1, maximum of 2.66 mm h-1, and a minimum of 0.21 mm h-1, and presented one failure. It was not possible to determine the infiltration rate of water in the channel of the terrace 04 in a typical Ultisol, due to the lack of impoundment of water during the whole period. The terrace 05 installed in Inceptisol imperfectly drained clayey texture had three failures and the highest occupancy rate of the section for the longest time. Terraces 06 and 07 in Oxisols of clayey texture were not occupied with water from the runoff for periods that allowed the reading of the measuring rules, probably due to the high rates of infiltration that could not be determined. Rulers 08, 09 and 10, installed in typical Ultisol of sandy / medium texture, were monitored on the same terrace and presented distinct results despite the proximity. The infiltration rate of slide 08 was on average 0.65 mm h-1, maximum 1.35 mm h-1 and minimum 0.21 mm h-1. Ruler 09 presented a mean of 0.80 mm h-1, a maximum of 1.67 mm h-1 and a minimum of 0.11 mm h-1, and presented a hydraulic failure. Terrain 11, installed in Ultisol of medium / clayey texture presented average infiltration rate of 0.72 mm h-1, maximum of 1.82 mm h-1 and minimum of 0.06 mm h-1, while that the terrace 12, implanted in the same soil of rule 11, presented an average rate of 0.85 mm h-1, 2.14 mm h-1 of maximum value and a minimum of 0.12 mm h-1. The results showed that the infiltration rates of water in the channel of the terraces are in most cases insufficient to store the amount of runoff produced in the area between terraces and on the roads near the terraces.
24

Percepção, recomendação e adoção do terraceamento agrícola comparadas ao seu funcionamento / Perception, recommendation and adoption of agricultural terracing compared to its operation

Alexandre Puglisi Barbosa Franco 05 October 2018 (has links)
O desenvolvimento científico na área de conservação do solo teve pouco progresso nos últimos trinta anos. A utilização de modelos para prever a erosão do solo cujos resultados foram derivados de análises de dados de parcelas em países de climas temperados, não produziram os prometidos modelos que resolveriam as questões centrais da conservação do solo, e as questões ambiciosas foram trocadas pelas limitadas e fáceis de responder. Em virtude das mudanças tecnológicas na mecanização agrícola e o aumento do tráfego de máquinas nas áreas de produção, um novo cenário de conservação do solo aparece como base de uma reestruturação das recomendações de práticas conservacionistas. A ciência produz resultados com desasagem de tempo em relação à demanda do setor agrícola e as inovações e mudanças de manejo acabam sendo implantadas sem embasamento científico. Para entender a relação e a distância que existe entre as recomendações científicas e as práticas aplicadas no manejo agrícola na cana-de-açúcar no Estado de São Paulo um questionário foi aplicado em profissionais da área de conservação de três setores de atuação, setor de produção, setor público e comunidade científica. Os resultados mostraram que a aplicações de manejo e práticas de conservação do solo no Brasil estão fundamentadas em conhecimento popular oriundas de recomendações empíricas, simplificadas e generalizadas como uma receita única para uso em todas as condições edafoclimáticas. Há predominânica de práticas de infiltração implantadas de forma isolada sem dimensionamento adequado e adoção de práticas complementares e com negligência das práticas de drenagem. Devido ao grande número de casos de voçorocas causadas por falhas hidráulicas de terraços de infiltração nos últimos anos um experimento de campo foi implantado com objetivo de medir a variação da lâmina de água represada em canais de terraços de infiltração para determinar a taxa de infiltração de água. Foram determinadas as taxas de infiltração em doze terraços de infiltração. Os resultados do terraço 01, instalado em Latossolo Vermelho Amarelo Típico de textura média, mostraram ocupação do canal do terraço durante todo o período de avaliação e uma taxa de infiltração média de 0,79 mm h-1, com máxima de 1,83 mm h-1 e mínima de 0,17 mm h-1. O terraço 01 apresentou duas falhas hidráulicas com chuvas acumuladas de 6 dias acima de 90 mm. O terraço 02 instalado em Neossolo Quatzarênico Órtico, a taxa de infiltração foi de 0,87 mm h-1 em média, com valor máximo de 1,73 mm h-1 e mínimo de 0,26 mm h-1 e não apresentou falhas, entretanto outros terraços na mesma área apresentaram falhas com chuva acumulada de 5 dias que ultrapassaram os 90 mm. O terraço 03, em Latossolo Vermelho Típico de textura argilosa, apresentou taxa de infiltração média de 1,32 mm h-1, máxima de 2,66 mm h-1, e mínima de 0,21 mm h-1 e apresentou uma falha. Não foi possível determinar a taxa de infiltração de água no canal do terraço 04 em Nitossolo Típico, devido a inexistência de represamento de água durante todo o período. O terraço 05 instalado em Cambissolo Háplico textura argilosa imperfeitamente drenado apresentou três falhas e a maior taxa de ocupação da seção pelo maior tempo. Os terraços 06 e 07 em Latossolos de textura argilosa não foram ocupados com água proveniente de enxurrada por períodos que permitissem a leitura das réguas de medição, provavelmente pelas altas taxas de infiltração que não puderam ser determinadas. As réguas 08, 09 e 10, instaladas em Argissolo Vermelho Amarelo Típico de textura arenosa/média, foram monitorados no mesmo terraço, porém apresentaram resultados distintos apesar da proximidade. A taxa de infiltração da régua 08 foi em média de 0,65 mm h-1, máximo de 1,35 mm h-1 e mínimo de 0,21 mm h-1. A régua 09 apresentou média de 0,80 mm h-1, máximo de 1,67 mm h-1 e mínimo de 0,11 mm h-1, e apresentou um a falha hidráulica. O terraço 11, instalado em Argissolo Vermelho Amarelo Típico de textura média/argilosa apresentou taxa média de infiltração de 0,72 mm h-1, máximo de 1,82 mm h-1 e mínimo de 0,06 mm h-1, enquanto que o terraço 12, implantado no mesmo solo da régua 11, apresentou taxa média de 0,85 mm h-1, 2,14 mm h-1 de valor máximo e mínimo de 0,12 mm h-1. Os resultados evidenciaram que as taxas de infiltração de água no canal dos terraços na maioria dos casos são insuficientes para armazenar a quantidade de enxurrada produzida na área entre terraços e nas estradas próximas aos terraços. / The scientific development in soil conservation has made little progress in the last thirty years. The use of models to predict soil erosion based on results derived from plot data analyzes in temperate countries did not produce the promised models that would solve the central issues of soil conservation, and the ambitious issues were exchanged for the limited and easy to respond. Due to the technological changes in agricultural mechanization and the increase of machine traffic in production areas, a new soil conservation scenario appears as the basis for a restructuring of the recommendations of conservation practices. Science produces results with a time lag in relation to the demand of the agricultural sector and the innovations and changes of management end up being implanted without scientific base. In order to understand the relationship and the distance between the scientific recommendations and the practices applied in the agricultural management of sugarcane in the State of São Paulo, a questionnaire was applied to professionals in the conservation area of three sectors of activity, production sector , public sector and scientific community. The results showed that the management applications and soil conservation practices in Brazil are based on popular knowledge derived from empirical, simplified and generalized recommendations as a unique recipe for use in all soil and climatic conditions. There is a predominance of infiltration practices implanted in isolation without adequate sizing and adoption of complementary practices and with neglect of drainage practices. Due to the large number of gully cases caused by hydraulic failures of infiltration terraces in the last years a field experiment was deployed with the objective of measuring the variation of the retained water slide in channels of infiltration terraces to determine the rate of infiltration of water . Infiltration rates were determined on twelve infiltration terraces. The results of the terrace 01, installed in Typical Yellow Red Oxisol of medium texture, showed occupation of the terrace channel throughout the evaluation period and a mean infiltration rate of 0.79 mm h-1, with a maximum of 1.83 mm h-1 and minimum of 0.17 mm h-1. The terrace 01 had two hydraulic failures with accumulated rains of 6 days above 90 mm. The terrace 02 in Entisol Quartzipsamments, had an average infiltration rate of 0.87 mm h-1, with a maximum value of 1.73 mm h-1 and a minimum of 0.26 mm h-1, and showed no failures, although other terraces in the same had failures with cumulative rain of 5 days that exceeded 90 mm. In the typical Oxisol with clay texture, the terrace 03 had a mean infiltration rate of 1.32 mm h-1, maximum of 2.66 mm h-1, and a minimum of 0.21 mm h-1, and presented one failure. It was not possible to determine the infiltration rate of water in the channel of the terrace 04 in a typical Ultisol, due to the lack of impoundment of water during the whole period. The terrace 05 installed in Inceptisol imperfectly drained clayey texture had three failures and the highest occupancy rate of the section for the longest time. Terraces 06 and 07 in Oxisols of clayey texture were not occupied with water from the runoff for periods that allowed the reading of the measuring rules, probably due to the high rates of infiltration that could not be determined. Rulers 08, 09 and 10, installed in typical Ultisol of sandy / medium texture, were monitored on the same terrace and presented distinct results despite the proximity. The infiltration rate of slide 08 was on average 0.65 mm h-1, maximum 1.35 mm h-1 and minimum 0.21 mm h-1. Ruler 09 presented a mean of 0.80 mm h-1, a maximum of 1.67 mm h-1 and a minimum of 0.11 mm h-1, and presented a hydraulic failure. Terrain 11, installed in Ultisol of medium / clayey texture presented average infiltration rate of 0.72 mm h-1, maximum of 1.82 mm h-1 and minimum of 0.06 mm h-1, while that the terrace 12, implanted in the same soil of rule 11, presented an average rate of 0.85 mm h-1, 2.14 mm h-1 of maximum value and a minimum of 0.12 mm h-1. The results showed that the infiltration rates of water in the channel of the terraces are in most cases insufficient to store the amount of runoff produced in the area between terraces and on the roads near the terraces.
25

Formation, Deformation, and Incision of Colorado River Terraces Upstream of Moab, Utah

Jochems, Andrew P. 01 August 2013 (has links)
Fluvial terraces contain information about incision, deformation, and climate change. In this study, a chronostratigraphic record of Colorado River terraces is constructed from optically stimulated luminescence (OSL) dating of Pleistocene alluvium and real-time kinematic (RTK) GPS surveys of terrace form. This record is analyzed to relate terrace formation to late Pleistocene climate fluctuations, and terrain analyses and longitudinal profile patterns reveal recent salt-related activity in the northern Paradox Basin as well as patterns in Colorado Plateau incision. A well-preserved, correlative suite of mainstem (M) fluvial deposits exists along the Colorado River upstream of Moab, Utah. Absolute dates indicate sedimentation >70 ka (M7, M6/M5), 70-50 ka (M4), 50-40 ka (M3), and 35-25 ka (M2). The M4 and M2 formed during the crescendo to glacial maxima, but the M7, M6/M5, and M3 were deposited during variable climate of marine isotope stages (MIS) 5 and 3. Deposits include thin (<7 m) strath terraces and thick (10-20 m) fill terraces. Our results suggest that terrace sedimentation is linked to enhanced sediment flux during glaciations in Rocky Mountain headwaters (M4 and M2), but major deposits also formed during dryland tributary sediment loading with markedly different timing (M6/M5 and M3). Conversely, incision may be driven by higher deglacial flows. Clast provenance data demonstrate greater percentages of locally-sourced sediment in M6/M5 and M3 deposits. Valley-bottom geometry and neotectonics control terrace form, with strath terraces found in bedrock-restricted reaches and fill terraces in wider valleys. Previously speculated salt deformation in this area is confirmed by localized collapse preserved in M4 stratigraphy in the Cache Valley graben and ~15 m of broader subsidence upstream. Concavity and knickzone distributions in tributary profiles are discordant and represent subtle expressions of salt-tectonic activity. Finally, a surprisingly rapid incision rate of ~900 m/Ma over the past ~70 ka suggests that the Colorado River may be responding to flexural rebound in the central plateau, but is faster than that predicted by the debated bull's-eye pattern of regional incision. This locally high rate may also reflect a transient wave of incision, as suggested by increased Pleistocene rates interpreted by studies in Glen and Grand canyons.
26

Quaternary Incision, Salt Tectonism, and Landscape Evolution of Moab-Spanish Valley, Utah

Mauch, James P. 01 May 2018 (has links)
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.
27

Vilniaus miesto želdynų sistemos formavimas / Formation of the green terraces system in Vilnius city

Dlugauskaitė, Asta 14 January 2009 (has links)
Miestuose kuriama vientisa želdynų sistema. Naudojami esami gamtiniai ištekliai – želdiniai, miškai, upės ir upelių slėniai, šlaitai, pakrantės bei kitos vertingos gamtos teritorijos. Išlaikomi užstatytųjų ir atvirųjų, skirtų gyventojų poilsiui ir sveikatai, optimalūs ploto santykiai taip pat ekologiniai, funkciniai ir estetiniai ryšiai. Išsaugomi esami vertingi želdiniai, prielaidos plėsti želdinius, tinkamai panaudoti jų rūšinę sudėtį, tinkamai eksploatuoti, saugoti nuo sunykimo. Želdynų sistemos formavimas yra sudėtingas daug laiko reikalaujantis procesas. Norint sistemingai formuoti želdinius turime gerai ištirti projektuojamų želdynų paskirtį, jų funkcijas, nustatyti kokį vaidmenį želdiniai turės atlikti ne tik bendroje želdynų kūrimo sistemoje, bet ir atskirose jų dalyse. Taip pat įvertinti ekologines sąlygas: vietovės klimatą, dirvožemius, aplinkos užterštumą ir gyventojų poilsį. Vilniaus istorinis centras, Senamiestis, yra vienas didžiausių Rytų Europoje (360 ha). Dėl savo unikalumo 1994 m. jis buvo įtrauktas į UNESCO svarbiausių pasaulio saugotinų objektų sąrašą. Vilniaus mieste želdynai užima 2865,7 ha bendro miesto ploto. Želdinių reikšmė miesto žmonėms yra didžiulė ir įvairiapusiška. Želdiniai gerina mikroklimatą, apsaugo nuo įvairių neigiamų faktorių, psichologiškai teigiamai veikia žmones. Želdiniai sukuria estetišką miesto aplinką, jungia pastatus ir įrenginius su urbanizuotu arba gamtiniu kraštovaizdžiu. / The purpose of the research – to analyze the green terraces of Vilnius basing on the general plan of Vilnius city municipality. The local government council of Vilnius confirmed the general plan of the territory of Vilnius municipality by the decision No. T – 242, 29 th may, 2003. Territory planning is one of the best integrated measures, the realization of the results of which is balanced city expansion. In the cities integral system of green terraces is under development. For this purpose current natural resources are being used – green terraces, forests, rivers and streams’ valleys, sides of hills, strands and other valuable territories of the nature; optimal ratios are maintained among built-up and open (green) areas that are meant for recreational and health purposes of the city’s system of green terraces. There must be preconditions created in the system for expansion of green terraces, for proper use of their trivial composition, proper exploitation and protection from extinction and etc. Development of green terraces’ system improves quality of the living environment, expands recreational areas in nature, increases city’s capacity to be more attractive for living, and ensures conditions for maintenance of ecosystems’ balance ant biological variety in the territory of the whole city. It is planned to invest larger amounts of money that are necessary for development of green terraces’ system.
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Natural and Cultural Landscape Evolution during the Late Holocene in North Central Guatemalan Lowlands and Highlands

Avendano, Carlos Enrique 20 August 2012 (has links)
Paleoecology has been only in recent decades applied to Mesoamerica; this thesis provides new records of paleoenvironmental changes in Guatemala. Paleoecological reconstructions are developed based mainly on pollen in the Lachuá lowlands and Purulhá highlands of the Las Verapaces Region. For the first time, quantitative vegetation and climate analyses are developed, and plant indicator taxa from vegetation belts are identified. Changes in vegetation are explained partially by elevation and climatic parameters, topography, drainage divides, and biogeography. Pollen rain and indicator plant taxa from vegetation belts were linked through a first modern pollen rain analysis based on bryophyte polsters and surface sediments. The latter contain fewer forest-interior plant taxa in both locations, and in the highlands, they contain higher local pollen content than in the lowlands. These calibrations aided vegetation reconstructions based on fossil pollen in sediment records from the Lachuá and Purulhá regions. Reconstructions for the last ~2000 years before present (BP) were developed based on fossil pollen from cores P-4 on a floodplain in Purulhá, and L-3, a wetland in Lachuá. Core P-4 suggests that Mayan populations developed a system of agricultural terraces in a former paleolake-swamp environment, which was abandoned at the time of the Spanish Conquest (~400 BP). Core L-3 indicates the abandonment of Mayan “Forest Gardens” at the time of the early Postclassic. These gardens likely prevailed during the Classic period (~300-1100 yrs BP) at the outskirts of the ancient city of Salinas de los Nueve Cerros. Following abandonment, forest recovery took place for about 800 yrs. Cultural factors are found to be more important in determining vegetation dynamics in this region, since no clear evidence of climate forcing was found. The P-4 and L-3 cores provide likely evidence that Mayan populations were, contrary to other evidence, innovative landscape managers. Scenarios in the Las Verapaces Region have been drastically modified in recent times (e.g. after the European Conquest), as suggested by pollen evidence in the top of both P-4 and L-3 cores, possibly due mostly to modern large scale natural resources exploitation, which represent environmental threats greater than any seen in the last ca. 2000 years.
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Natural and Cultural Landscape Evolution during the Late Holocene in North Central Guatemalan Lowlands and Highlands

Avendano, Carlos Enrique 20 August 2012 (has links)
Paleoecology has been only in recent decades applied to Mesoamerica; this thesis provides new records of paleoenvironmental changes in Guatemala. Paleoecological reconstructions are developed based mainly on pollen in the Lachuá lowlands and Purulhá highlands of the Las Verapaces Region. For the first time, quantitative vegetation and climate analyses are developed, and plant indicator taxa from vegetation belts are identified. Changes in vegetation are explained partially by elevation and climatic parameters, topography, drainage divides, and biogeography. Pollen rain and indicator plant taxa from vegetation belts were linked through a first modern pollen rain analysis based on bryophyte polsters and surface sediments. The latter contain fewer forest-interior plant taxa in both locations, and in the highlands, they contain higher local pollen content than in the lowlands. These calibrations aided vegetation reconstructions based on fossil pollen in sediment records from the Lachuá and Purulhá regions. Reconstructions for the last ~2000 years before present (BP) were developed based on fossil pollen from cores P-4 on a floodplain in Purulhá, and L-3, a wetland in Lachuá. Core P-4 suggests that Mayan populations developed a system of agricultural terraces in a former paleolake-swamp environment, which was abandoned at the time of the Spanish Conquest (~400 BP). Core L-3 indicates the abandonment of Mayan “Forest Gardens” at the time of the early Postclassic. These gardens likely prevailed during the Classic period (~300-1100 yrs BP) at the outskirts of the ancient city of Salinas de los Nueve Cerros. Following abandonment, forest recovery took place for about 800 yrs. Cultural factors are found to be more important in determining vegetation dynamics in this region, since no clear evidence of climate forcing was found. The P-4 and L-3 cores provide likely evidence that Mayan populations were, contrary to other evidence, innovative landscape managers. Scenarios in the Las Verapaces Region have been drastically modified in recent times (e.g. after the European Conquest), as suggested by pollen evidence in the top of both P-4 and L-3 cores, possibly due mostly to modern large scale natural resources exploitation, which represent environmental threats greater than any seen in the last ca. 2000 years.
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Vėlyvojo Nemuno apledėjimo keiminių terasų morfogenezė ir jų erdvinė sklaida / The morphogenesis and spatial spread of the kame terraces of the Late Nemunas Glaciation

Karmazienė, Danguolė 19 May 2014 (has links)
Keiminės terasos Lietuvos teritorijoje yra aptinkamos Vėlyvojo Nemuno apledėjimo Baltijos stadijos ledyno paliktame reljefe. Pagrindinis šio darbo tikslas – Vėlyvojo Nemuno apledėjimo srityje esančių keiminių terasų paplitimo, jų morfologijos, sandaros, kilmės ir padėties ištyrimas. Ankstesnėse publikacijose buvo tik konstatuojama keiminių terasų geomorfologinė padėtis ir aprašomi morfologiniai terasų požymiai. Pagrindiniu tyrimo metodu pasirinktas kartografinis. Keiminės terasos yra savarankiški ledyno pakraštiniai dariniai, susidarę tarp reljefo formų, susiformavusių supraglacialinėje ir terminoglacialinėje subaplinkose. Ledyno ledo dangos šlaitas buvo tik viena iš jas sudarančių nuogulų sedimentacinės erdvės ribų. Terasų vidinė sandara tiesiogiai priklauso nuo ją formavusių veiksnių. Pagal tai skiriamos fliuvioglacialinės, limnoglacialinės ir mišrios akvaglacialinės keiminės terasos. Darbe pateikta klasifikacija paremta keiminių terasų Lietuvos teritorijoje morfologijos, morfometrijos ir sandaros tyrimais. Atlikti tyrimai svarbūs fundamentiniu aspektu, nes nustatyta skirtingų keiminių terasų tipų morfogenezė, sandara ir susidarymo paleogeografinės sąlygos, degraduojant Vėlyvojo Nemuno apledėjimo ledynui, gali būti panaudota kituose regionuose sprendžiant analogiškų formų susidarymo klausimus. Darbą sudaro 167 psl., 88 paveikslai, 1 lentelė. Literatūros sąraše 173 bibliografiniai pavadinimai. / Kame terraces in the territory of Lithuania are found in the Late Nemunas glaciation Baltija stage relief. Investigation of the distribution, morphology, composition, origin and position of kame terraces in the Late Nemunas glaciation area is the main objective of the present study. The previous publications merely contained statements about the geomorphological position of kame terraces and descriptions of morphological features of terraces. The research was carried out by cartographic method. Kame terraces are isolated glacier marginal formations deposited between the landforms that formed in supraglacial and terminoglacial environments. The ice slope of a decaying glacier only represented one of the boundaries of sedimentation space. The structure of terraces was directly affected by the forming factors. According to the forming factors, kame terraces are classified as glaciofluvial, glaciolacustrine and mixed aquaglacial. The presented classification is based on the studies of morphology, morphometry and structure of kame terraces in the territory of Lithuania. The conducted study has a fundamental value since the established morphogenesis, structure and palaeogeographical conditions of formation of different types of kame terraces, created by the decaying Late Nemunas glacier, can be used for solution of the formation issues of similar forms in other regions. The dissertation is comprised of 167 pages, 88 illustrations and one table. The list of references has 173... [to full text]

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