Pollen profiles from two lakes, Tawny Pond (44°48’59”N, 77°10’54”W, 276m) and Stoll Lake (44°58’16”N, 77°17’22”W,303m) in Addington Highlands, eastern Ontario, Canada were analyzed to understand the effects of late-Holocene climate change and European settlement on eastern Ontario’s forests. Both lakes were analyzed at high temporal resolution and record vegetation dynamics over the last 1000 years. Throughout the past 1000 years, Pinus, Tsuga, Betula, Quercus, Acer and Fagus were the dominant taxa in the pollen record. The pollen records show vegetation response in relation to the Medieval Warm Period and the Little Ice Age. From 970-1200 AD the forest was dominated by hemlock, beech and maple trees. From 1200-1870 AD the forest composition changed as pine and boreal trees became more abundant and/or had increased relative pollen production. Most recently, since 1870 AD, herbaceous plants (weeds) increased, whereas softwoods decreased and hardwoods increased, due to landscape changes associated with European settlement. These results show that high resolution studies of unvarved lakes, with an appropriate chronology, can detect multi-decadal climate variability. This thesis was also concerned with making management suggestions to the forestry community. Future climate change will likely create a forest composition more similar to that of the Medieval Warm Period than the time of European colonization, and thus should be the basis for forest planning.

Scimitar Glacier originates below the northeast face of Mt. Waddington in the southern British Columbia Coast Mountains and flows 18 km down valley to calve into a proglacial lake. The purpose of this research was to describe the late Holocene glacier history of Scimitar Glacier using stratigraphic analysis in conjunction with dendroglaciologic and radiocarbon dating techniques. Downwasting of the glacier surface has exposed stacked till units separated by wood-bearing horizons in the proximal slopes of lateral moraines flanking the glacier at several locations. Historical moraine collapse and erosional breaching has also revealed the remains of standing trees buried in sediments from a lake originally ponded against the distal moraine slope. Radiocarbon dating of detrital wood remains revealed that Scimitar Glacier expanded down-valley at least three times in the late Holocene. The earliest period of expansion occurred 3167-2737 cal yr BP in association with the regional Tiedemann Advance. Following this the glacier receded and downwasted prior to advancing to reconstruct the lateral moraine in 1568-1412 cal yr BP during the First Millennial Advance. The most recent phase of moraine construction was initiated during late Little Ice Age glacial expansion before 1742 AD and extended until at least 1851 AD, after which Scimitar Glacier began to recede and downwaste. Field investigations at Scimitar Glacier allowed for the construction of a late Holocene history of glacier expansion and lateral moraine construction that spans the last 3000 years. This record is comparable to that recorded at other glaciers in this region, and confirms the long-term relationship between regional climate trends and glacier behaviour in this setting. / Graduate

Modern Kusawa Lake (60° 19' 55” N, 136° 4' 48” W, 142 km2) of southwestern Yukon Territory drains a 4290 km2 catchment, 4.7 % of which is glacier covered. Sediment cores show variability both down-lake and within specific sub-basins of the lake. In Regions II -V of Kusawa Lake, sediments are mainly clastic with massive to weakly laminated silts and clays interrupted by fine sand units, which reflect distinct runoff events into Region IV from glacier sources. In Region I, massive silts, silt-clay couplets are interrupted by thick sand deposits derived from the Primrose River delta. Further up-lake, the sediment record is further interrupted by modern sediment delivery from the Kusawa Campground alluvial fan. The relatively small accumulation of lake glacial and Holocene sediment input in Kusawa Lake is similar to other large lakes of the Canadian Cordillera. These patterns reflect a particular style of deglaciation and Holocene sediment inputs.

Modern Kusawa Lake (60° 19' 55” N, 136° 4' 48” W, 142 km2) of southwestern Yukon Territory drains a 4290 km2 catchment, 4.7 % of which is glacier covered. Sediment cores show variability both down-lake and within specific sub-basins of the lake. In Regions II -V of Kusawa Lake, sediments are mainly clastic with massive to weakly laminated silts and clays interrupted by fine sand units, which reflect distinct runoff events into Region IV from glacier sources. In Region I, massive silts, silt-clay couplets are interrupted by thick sand deposits derived from the Primrose River delta. Further up-lake, the sediment record is further interrupted by modern sediment delivery from the Kusawa Campground alluvial fan. The relatively small accumulation of lake glacial and Holocene sediment input in Kusawa Lake is similar to other large lakes of the Canadian Cordillera. These patterns reflect a particular style of deglaciation and Holocene sediment inputs.

This thesis documents Agate Basin archaeological remains in the provinces of Alberta and Saskatchewan. By extension, it examines the context of the rapidly changing Late Pleistocene/Early Holocene environment. A database of information on Agate Basin sites in the study area is assembled. Site analysis allowed for the examination of Agate Basin adaptations based on radiocarbon chronology, landform use, mobility, resource use, projectile point production and climate and environmental context. The results confirm that Agate Basin producing peoples within Alberta and Saskatchewan displayed variability concerning projectile point production, landscape use, resource extraction, and hunting practice. It appears that Agate Basin producing people within Alberta and Saskatchewan practiced a predominantly broad-based strategy for procuring resources. No evidence exists to support a model of large-scale communal hunting. Likely, the strongest influence on the particular adaptive behaviours of Agate Basin producing people in Alberta and Saskatchewan can be summarized as environmental.

Lake biotic responses to natural climate variability, fire disturbances, and human impacts over the Holocene were studied at two proximate sites in southwestern Québec. Sediments from Lac Noir and Lac Brûlé had annually deposited laminations (varves), enabling for the precise dating of continuous time-series and high-resolution analysis of subfossil diatom assemblages. The Lac Noir (45°46’31”N, 75°8’23”W, 176 m a.s.l.) record spanned ~11000 years of the Holocene. Stratigraphic changes in diatom assemblages of the lake could be divided into early, mid-, and late periods, broadly paralleling Milankovitch-scale climate intervals and vegetation changes inferred from regional palynological records. The early Holocene (11.1-8.0 ka) climate was cooler and dry, vegetation in the region was comprised of Picea-dominated woodlands, and the lake diatom flora included primarily benthic taxa. Warming in the mid-Holocene (8.0-3.6 ka) allowed for stabilization of soils and forests in the catchment, stronger thermal stratification in the lake, and resultant increases in oligo-mesotrophic diatom taxa such as Discostella stelligera. During the late Holocene (3.6 ka to present), an increase in the abundance of deciduous trees (e.g. Betula and Alnus) in response to cooling led to nutrient-enrichment and higher overall lake productivity. The record from Lac Brûlé (45°43’09”N, 75°26’32”W, 270 m a.s.l.) encompassed the last ~1200 years of the late Holocene. Generalized additive models (GAM) revealed a tight coupling between diatoms and catchment-mediated processes (e.g. vegetation and disturbances), which were closely aligned with climate variations. During the Medieval Warm Period (800-1300 CE), pollen-based inferences of warmer summer temperatures were associated with high abundances of Cyclotella bodanica var. intermedia and Cyclotella rossii; this signalled oligotrophic lake conditions and prolonged thermal stratification. The onset of the Little Ice Age (1450-1850 CE) marked a cooling in the region, and a decline in Tabellaria flocculosa str. IIIp indicated increased nutrient loading from the catchment area. Situated less than 300m from Lac Brûlé are remnants of the Wallingford-Back Mine, which ran from 1924-1972 CE; activities at the mine resulted in local changes to nutrient availability and primary productivity at this site. In previous studies of both Lac Noir and Lac Brûlé, pollen records had indicated overall similarities in the vegetation histories in response to climate variability during the late Holocene. Diatom assemblages were influenced by individual lake conditions and were thus unique to each site; nevertheless, they were closely linked with local and regional patterns of vegetation composition. A main point of difference in the paleo-records from both lakes was attributed to a local fire in the Lac Brûlé catchment at 1345 CE, which caused an early decline in hemlock (Tsuga). The decrease in hemlock was seen at Lac Noir only centuries later, and diatoms in each lake responded according to vegetation changes within their own respective catchments. This research shows that high-resolution sampling of lake sediments is able to detect diatom responses to both long-term and abrupt changes in the environment. Individual sites show similarly timed responses of other proxy-indicators, such as pollen and cladocera, to climate and land-use changes. However, distinct differences in the aquatic biota of well-dated proximate sites can be used to identify influences of regional climate variations, which are sometimes masked by localized, non-climatic processes.

This study used Jumbo Piston Core 126, collected from the Nathaniel B. Palmer during cruise NBP10-01, to investigate environmental variability in Barilari Bay, western Antarctic Peninsula as part of the LARsen Ice Shelf System, Antarctica (LARISSA) project. A total of 107 samples were collected every 20cm from a 21.42m sediment core. Benthic foraminiferal data from Jumbo Piston Core 126 was analyzed using Principal Component (PC), Canonical Correspondence Analysis (CCA), and cluster analyses to assist in the Holocene oceanographic and climatic interpretation of Barilari Bay. The first three principal components explain 79.5% of the variance in the foraminiferal abundance data. PC1 comprises 49.6% of the variance and represents the Bulimina aculeata assemblage. PC2 and PC3 explain 16.3% and 13.6% of the variance and characterize the Fursenkoina fusiformis and Pseudobolivina antarctica assemblages, respectively. F. fusiformis assemblage represents the presence of a less saline water mass associated with ice shelf decay. The agglutinated P. antarctica assemblage is indicative of Hyper Saline Shelf Water (HSSW). TheB. aculeata assemblage is associated with Upper Circumpolar Deep Water (UCDW) (Ishman and Domack, 1994) Sediments from ~1100-950 calibrated years Before Present (cal. yr BP) are characterized by theB. aculeata assemblage, indicating the presence of UCDW. At ~950 cal. yr BP the UCDW receded coincident with glacial conditions observed during what is interpreted as the Little Ice Age. The ~950-350 cal. yr BP interval represents glacial conditions interpreted from the high PC scores of the P. antarctica assemblage and low foraminiferal abundances due to HSSW and a high sedimentation rate from glacial runoff. Intermittent pulses of UCDW are observed in the 950-350 cal. yr BP interval, expressed by the PC peaks in the B. aculeata assemblage. Between ~300 and 100 cal. yr BP the middle of the fjord was dominated by the F. fusiformis assemblage, suggesting ice shelf decay and open marine conditions. At ~50 cal. yr BP UCDW progressed back into Barilari Bay and is currently the dominant water mass.

O presente estudo foi desenvolvido em uma turfeira localizada no baixo curso do rio Ribeira de Iguape, Litoral Sul de São Paulo com o objetivo de reconstituir os paleoambientes e as possíveis variações ambientais ocorridas na área por meio da análise de palinomorfos e das características dos sedimentos do testemunho de sondagem de 520 cm de profundidade. A análise de bio e geoindicadores permitiu reconstituir parte da história de evolução sedimentar holocênica da área. Para isso a análise foi fundamentada sob o ponto de vista da biogeografia, envolvendo a interpretação e correlação entre as variáveis: sedimentológicas, espongológica, foraminíferos, palinológicas e isótopos de 13C. Antes de 7.300 anos cal AP as características sedimentológicas evidenciam o início da sedimentação da planície de inundação onde foi depositado espículas de esponjas continentais de O. navicella, é provável que o aporte de água doce na área de estudo tenha causado o desaparecimento de espécies de foraminíferos, tecamebas e ostracodes pela dissolução das carapaças em águas com pH ácidos, o mesmo aporte que pode ter lixiviado o material polínico, pois os sedimentos são arenosos. Os elementos isotópicos com valores de -27,6 evidenciam que a matéria orgânica é de origem fluvial. Por volta de 7.300 anos AP (fácies 430 cm) o NRM cruzou o zero pela primeira vez no Holoceno. Essa interpretação é corroborada pela chegada de espículas de origem marinha nos sedimentos. Além disso, no nível de 430 cm observa-se redução da concentração de esponjas de água doce. Os valores de 13C - 25,9 indicam que a origem da matéria orgânica é mista. Entre 7.200 e 6.430 anos cal AP ocorreu novamente uma rápida regressão do NRM verificado pela presença frequente de esponjas continentais e raríssima presença de espículas marinhas. A área era colonizada por plantas típicas de ambientes sob influência marinha e fluvial como Asteraceae, Poaceae, Araceae, Begoniaceae, Ulmaceae, Arecaceae Bactris sp. (encontrada em áreas alagadas e/ou FPa). Antes de 6.430 anos cal AP ocorre o início da segunda e mais duradoura fase de transgressão marinha caracterizada pela espongofácies marinha e pela queda nas porcentagens de todos os táxons polínicos. O pico da transgressão ocorre antes de 5.124 anos cal AP nesse momento foi depositado material espicular marinho e continental evidenciando o ambiente estuarino, onde plantas herbáceas adaptadas a esse ambiente ainda colonizavam essa área com concentrações como Amaranthaceae. Posteriormente, o NRM decai lentamente chegando ao nível zero atual, aqui as porcentagens de espículas marinhas decaem paulatinamente até a profundidade de 225 cm. Por volta de 3.200 anos cal AP (médias das idades de 145 cm) o ambiente já se comportava como um pântano, há aumento na concentração de Bignoneaceae (Tabebuia), Cluseaceae (Clusia) e novamente Amaranthaceae sugerem a colonização de FPa. Plantas do gênero Tabebuia sp. destacam-se por se agruparem em áreas alagadas. Posteriormente, o aumento significativo nas concentrações polínicas de todos os táxons, principalmente dos indicadores de FPaT, indicam o desenvolvimento dessa formação vegetal. Devido à complexidade desse ambiente por causa de sua morfodinâmica há necessidade de cuidados na interpretação dos resultados, pois os registros de mega-eventos podem ser confundidos, mascarar ou levar as interpretações paleoambientais inadequadas. Por isso, o uso de multiindicadores e o conhecimento dos processos mostraram-se fundamentais e foi possível obter uma excelente resposta. / This study was developed in a peat bog located on the lower course of Ribeira river, South Coast of Sao Paulo, in order to reconstruct the paleoenvironments and possible environmental changes occurred in the area through analysis of palynomorphs and the characteristics of the sediments drill core depth of 520 cm. The analysis of bio and geoindicators allowed to reconstruct a part of the history of the Holocene sedimentary evolution of the area. The analysis was based on the point of view of Biogeography, involving the interpretation and correlation between variables: sedimentological, belong sponge, foraminifera, pollen and 13C isotopes. Before 7300 cal years BP the sediment characteristics show the beginning of sedimentation of the floodplain where it was deposited spicules of sponges continental O. navicella, it is likely that the freshwater inflow in the study area has caused the disappearance of species of foraminifera, ostracods and thecamoebian by dissolving the shells in waters with acidic pH, the same approach that may have leached the pollen material, because the sediments are sandy. The isotopic elements with values of -27.6 show that the organic matter is of fluvial origin. Around 7300 years BP (430 cm depth) NRM crossed zero for the first time in the Holocene. This interpretation is corroborated by the presence of spicules in the sediments of marine origin. Furthermore, at the level of 430 cm was observed a reduction of the concentration of freshwater sponges. 13C values of -25.9 indicate that the source of the organic matter is mixed. From 7200 until 6430 years cal AP occurred a rapid regression of NRM verified by the frequent presence of continental sponges and extremely rare presence of marine spicules. The area was colonized by plants typical of marine and fluvial environments under influence like Asteraceae, Poaceae, Araceae, Begoniaceae, Ulmaceae, Arecaceae Bactris sp. (found in flooded and / or FPa areas). Before 6430 years cal AP occurred the beginning of the second and more lasting phase of marine transgression characterized by marine espongofácies and for the decreased in percentages of all pollen taxa. The peak transgression occurs before 5124 years cal AP, when was deposited marine and continental espicular materials evidencing the estuarine environment, where herbaceous plants adapted to this environment yet colonized this area with concentrations as Amaranthaceae. Subsequently, the NRM decays slowly coming to the current zero level. Here the percentages of marine spicules decay gradually to a depth of 225 cm. Around 3200 cal years BP (mean ages of 145 cm) the environment has behaved like a swamp, there is an increase in the concentration of Bignoneaceae (Tabebuia), Cluseaceae (Clusia) and again Amaranthaceae suggest colonization of FPa. The genus Tabebuia sp. stands out for getting together in wetlands. Later, the significant increase in the pollen concentrations of all taxa, especially indicators of WPF, indicates the development of this plant formation. Due to the complexity of this environment because of their morphodynamics, caution is necessary in interpreting of the results because the records of megaevents can be confused, to mask or take inadequate paleoenvironmental interpretations. Therefore, the use of multi-indicators and the knowledge of the process were essentials and it was possible to obtain excellent response.

O delta do rio Tubarão, situado na costa centro-sul catarinense entre os municípios de Tubarão, Jaguaruna e Laguna, constitui raro exemplo de delta lagunar ativo no Brasil. Sua planície deltaica cobre área aproximada de 250km2, onde são encontradas evidências de migração de canais fluviais dadas por séries de truncamentos de antigos distributários, alguns ainda ativos. Dez testemunhos foram obtidos junto aos principais canais distributários do rio Tubarão, a partir dos quais foram realizadas análises de fácies, granulométrica, de minerais pesados, de teor de matéria orgânica e de relações químio-isotópicas, além de datações 14C. Também foram levantados acervos históricos de fotografias aéreas e de dados de prospecção mineral de subsuperfície. Cerca de 5000 anos atrás, na região de seu ápice, próximo ao rio tributário Capivari de Baixo, o delta do rio Tubarão ingressou numa antiga baía lagunar e ramificou-se em sete distributários principais que, desde seus momentos iniciais de migração, foram controlados por avulsões autogênicas rumo a antigas depressões do fundo da bacia receptora. Tais avulsões progradaram o delta inicialmente para SW, depois para ENE, e então para NNE, favorecendo a fragmentação da antiga baía lagunar em uma série de lagos e lagunas menores. Diante deste cenário dinâmico, sambaquis foram erigidos no entorno do sistema lagunar, constituindo importantes registros arqueológicos de interação entre evolução sedimentar e ocupação humana pré-histórica. O resultado das análises granulométricas indicou que a sedimentação deltaica, nas proximidades de encostas de morros, foi misturada com colúvio e/ou depósitos de fluxos gravitacionais, como evidenciado pela presença de intervalos texturalmente muito imaturos em alguns testemunhos. Em relação à análise de minerais pesados, o principal fator de controle nas variações da assembleia em depósitos de delta e de bacia é a proveniência sedimentar. Em termos mediatos, essa proveniência reflete fontes plutônicas e metamórficas (médio a alto grau) do Batólito de Florianópolis (e xenólitos associados) e do Complexo Granito-Gnáissico, e rochas arenáceas alteradas da Bacia do Paraná. Em termos imediatos, depósitos deltaicos destacam-se pela afinidade mineralógica com as areias do rio Tubarão, inferida sobretudo a partir da presença mútua de grãos alterados de cianita e estaurolita, enquanto que depósitos da bacia lagunar destacam-se por sua similaridade mineralógica com areias dos rios tributários Braço do Norte e Capivari de Baixo, neste caso principalmente pela presença de zircão. A matéria orgânica presente nos depósitos do delta e de sua bacia receptora resulta do aporte de fontes terrestres (fornecido pelos rios) e marinhas (trazido via desembocaduras lagunares), fato que é evidenciado pelos resultados de \'delta\'\'POT.13 C\', \'delta\'\'POT.15 N\' e razão \'C IND.ORG\'/\'N IND.TOTAL\'. Particularmente, nos sedimentos da bacia, variações entre diferentes tipos de matéria orgânica têm ocorrido ao longo do Holoceno, as quais são atribuídas tanto ao isolamento físico progressivo do sistema lagunar em relação ao mar aberto como por mudança climática regional (aumento destacado de precipitação). A análise isotópica de oxigênio (\'delta\'\'POT 18 O\') de conchas de moluscos em depósitos da bacia indicou enriquecimento relativo em \'ANTPOT.16 O\' durante o Holoceno. Este resultado, a exemplo daquele dos isótopos de carbono e de nitrogênio dos sedimentos, sugere isolamento gradual das águas lagunares em relação às de mar aberto. / The Tubarão river delta, located on the centre-south coast of Santa Catarina State, among the municipalities of Tubarão, Jaguaruna and Laguna, is rare example of active lagoonal delta in Brazil. Its delta plain covers an area of about 250km2, where there are evidences of migration of fluvial channels in a set of truncations of ancient distributaries, some of these still in activity. Ten cores were acquired adjacent to the main distributary channels of the Tubarão river, from which analyses of facies, grain size, heavy minerals, organic matter, chemistry-isotope ratios, and radiocarbon datings were performed. Also, aerial photographies and data of subsurface mining were surveyed from historical collections. Thereabout 5,000 years ago, in the region of its apex, near Capivari de Baixo tributary river, the Tubarão river delta entered an ancient lagoonal bay and branched seven main distributaries. Since the beginning of its migration, these distributaries were controlled by autogenic avulsions towards ancient depressions in the bottom of the basin. Initially, these avulsions prograded the delta towards SW, afterwards to ENE, and then to NNE, favoring the fragmentation of the ancient lagoonal bay in a set of smaller lakes and lagoons. Faced with this dynamical scenario, shellmounds were erected surrounding the lagoon system, composing important archaeological records of the interaction between sedimentary evolution and prehistoric human occupation. The results of the grain size analysis showed that the deltaic sedimentation, in the vicinity of slopes of hills, was mixed with colluvium and/or gravity flow deposits, that is evidenced by the presence of texturally very immature intervals in some cores. The analysis of heavy minerals, by its turn, showed that the main controlling factor in the variations of its assemblage in deposits of delta and basin is the sedimentary provenance. In terms of mediate sources, this provenance reflects plutonic and metamorphic (medium to high grade) rocks of the Florianópolis batholith (including its xenoliths) and of the Granite-Gneiss Complex, and weathered sedimentary sandstones of the Palaeozoic Paraná basin. Regarding immediate sources, deltaic deposits stand out by its mineralogical affinity with sands of the Tubarão river, mainly by the mutual presence of weathered grains of kyanite and staurolite, whereas deposits of the lagoon have mineralogical similarity with the sands of Braço do Norte and Capivari de Baixo tributary rivers, especially in relation to the presence of zircon. The origin of the organic matter found in the deposits of the delta and in its lagoonal basin is both from sedimentary input of terrestrial sources (provided by rivers) and marine (brought via inlets), fact evidenced by results of \'delta\'\'POT.13 C\', \'delta\'\' POT.15 N\', and \'C IND.ORG\'/\'N IND. TOTAL\' ratio. Particularly, in the sediments of the basin, variations between different types of organic matter have occurred during the Holocene, and are attributed both to the progressive physical isolament of the lagoon system from the open sea, and by local climate change (pronounced augment of precipitation). The isotope analyses of oxygen (\'delta\'\'POT.18 O\') of molluskan shells from the deposits of the basin present relative enrichment in \'ANTPOT.16 O\' during the Holocene. This result, as well as the one from isotope analyses of carbon and nitrogen of sediments, suggests gradual isolation of the lagoonal waters of influence of waters from the open sea.

No description available.