No description available.

No description available.

Palaeochannel development along the middle reaches of the River Irthing valley floor, Cumbria, UK, has been reconstructed via a range of palaeoenvironmental techniques. This has enabled the analysis of interactions between the geomorphological, hydrological and ecological components of the floodplain system during the mid to late Holocene. Geornorphological mapping, surveying and lithostratigraphic analysis of palaeochannel fills along a 2.5 kilometre reach of the valley floor has determined the character of Holocene channel and floodplain evolution and the physical context for palaeochannel habitat development. Chronological controls have been provided by historical map analysis and radiocarbon dating. The River Irthing valley floor experienced net fluvial incision from the Pleistocene-Holocene boundary up until the mid Holocene, while late Holocene floodplain evolution has been characterised by a series of channel avulsion and limited floodplain reworking. Periods of channel incision and planform change have been dated to 2440-1920 cal. BC, 670-970 cal. AD, 1410-1620 cal. AD and the late eighteenth to early nineteenth century AD. Five palaeochannel reaches with well-preserved organic rich channel fill sediments were selected for detailed lithostratigraphic analyses (by multiple core transects) and plant macrofossil analyses. Channel fills provide evidence of rapid biotic response to channel abandonment and subsequent changes to the physical characteristics and trophic status of the habitat. Hydroseral sequences from aquatic to wetland to floodplain woodland communities and the affects of human activity on palaeochannel development are also evident. The results indicate high magnitude flood inundation significantly affects vegetation succession and highlight the importance of physical processes and the landscape context in determining the characteristics of palaeochannel development. The research emphasises the application of plant macrofossil analysis to organic rich alluvial sediments.

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This study explores the utility of stable light isotopes in Chersina angulata (angulate or bowsprit tortoise) bone collagen as a paleoenvironmental proxy, to augment the limited range of proxies preserved in Southern Africa. δ¹³C and δ¹⁵N were measured in 76 archaeological tortoises from Elands Bay Cave and nearby Tortoise Cave. The samples range in age from the late Holocene to the terminal Pleistocene. δ¹⁵N values are not strongly correlated with δ¹³C, indicating different drivers of variation in the two isotopes. δ¹³C and δ¹⁵N values are lower between 154-487 cal. BP, which spans the Little Ice Age, compared with 744-1 042 cal. BP, which is the period of the Medieval Climate Anomaly (MCA). This implies that conditions were cool and wet during the LIA, and hot and dry during the early MCA. δ¹³C and δ¹⁵N values were higher during the early stages of the MCA (744-1 042 cal. BP), indicating drier conditions than in the late MCA (547-669 cal. BP). In the period prior to the MCA (1180-1357 cal. BP), lower δ¹³C and δ¹⁵N values indicate cooler, moister conditions. Higher δ13C values also indicate a temperature increase at the beginning of the Middle Holocene (4005-5 720 cal. BP). These findings are generally consistent with existing paleoenvironmental records from the Cederberg and Elands Bay region. The paleoenvironmental record generated from the tortoise carapace and plastron bone provides the first evidence from the terrestrial archaeological record for the LIA and MCA at Elands Bay. Hence, the tortoise record is able to provide a more detailed climate record than the charcoal and faunal record at EBC. This study shows that the analysis of stable isotopes in C. angulata from archaeological sites is a viable option for paleoenvironmental reconstruction.

No description available.

No description available.

The sites of Elandsfontein (EFT) and Duinefontein (DFT) preserve important records of mid-Pleistocene human occupation along South Africa's southwestern coast. In addition to human fossils in the case of EFT, both sites have produced extensive collections of artefacts and faunal remains. Analyses of the latter have provided the broad environmental contexts for mid-Pleistocene human occupation along this coast. Recently, research into landscape use by mid-Pleistocene human populations at EFT and DFT has highlighted the need for more precise palaeoenvironmental data for the region. In response to this need, I analysed plant phytoliths extracted from sediments sampled at EFT and DFT. The results of this analysis are reported and interpreted in this thesis. To assist with the interpretation of the EFT and DFT phytolith assemblages, I established a modern phytolith reference collection. In addition, pre-existing phytolith collections were examined and literature was consulted. Phytoliths extracted from modern and mid-Pleistocene aged sediments sampled at different localities at EFT and DFT were identified and tallied to determine vegetation composition during the middle Pleistocene. Distinctions were made between "grassier" and "more woody" samples. Analyses of modern plant samples confirmed that grass species produced abundant phytoliths, whereas the majority of dicotyledons did not produce diagnostic morphotypes. Phytoliths belonging to grass species currently growing in the region were identified in the modern sediment samples, as were non-grass phytoliths that included those from woody dicotyledonous and monocotyledon plants. The majority of the mid-Pleistocene sediment samples from EFT produced varying proportions of grass, woody dicotyledon, monocotyledon, sedge and palm type phytoliths which are characteristic of cool-season growing landscapes. In comparison to EFT, the late mid- Pleistocene sediment samples from DFT contained fewer phytoliths. These results suggest that the conditions at DFT were either not conducive to the preservation of phytoliths or that the vegetation was sparse and/or did not produce abundant phytoliths. Where sufficient phytoliths were preserved, assemblages suggested landscapes similar to that of EFT. In summary, analyses suggest that during the middle to late Pleistocene, a heterogeneous vegetation community, consisting primarily of C₃ grasses, woody dicotyledons and other monocotyledonous plants existed along South Africa's southwest coast. Furthermore, results support the longterm presence of the winter rainfall zone in the region. This study demonstrates the potential of phytolith analysis as an important proxy in determining the composition of palaeo-vegetation communities in South Africa. Although there were limitations that necessitated the broad classification of phytolith groups, the study nevertheless provided more precise information, particularly about mid-Pleistocene vegetation structure, that was not previously available.

No / In an earlier study, stress lines in primate teeth were found to occur on a recurrent basis, probably corresponding to seasonal fluctuations in environmental parameters, such as food availability (Macho et al., J. Hum. Evol. 30 (1996) 57¿70). In the present study this approach was extended to the study of teeth of extant and extinct mammals, with the specific aim to determine the pattern of seasonality at the Australopithecus anamensis-bearing site at Allia Bay, Kenya. It was found that extant and extinct species, who share similar dietary/ecological adaptations, are comparable in their patterns of stress. Typical browsers/mixed feeders were found to exhibit three recurrent disturbances per year, whereas grazers usually only exhibit two. The average spacing between lines is also comparable between extant and extinct species. Hence, while the severity and predictability of the seasons probably fluctuated during crucial periods of hominin evolution, there is little doubt that all hominins lived in a seasonal environment. At Allia Bay, the pattern of stress lines found in mammals suggests that the environmental conditions in which A. anamensis lived may have been comparable to those found in the Masai Mara today.

Bottom sediment is an archive of the historical changes in a lake and its catchment. This thesis is apalaeoenvironmental reconstruction of catchment processes in Bolgoda Lake situated in western SriLanka. We studied a sediment core retrieved from this lake. In our study, we focus on multiplephysical and chemical proxies: grain-size, loss-on-ignition, total organic carbon content, C:N ratio,and δ13C stored in the organic matter. The aim of this study is to contribute to a better understandingof the palaeoenvironmental conditions in the region and allow a comparison between this site andothers.In the deepest part of the core, we see an overall high sand content, which indicates a period ofhigher discharge into the lake compared to what the other core parts indicate. This is probably aresult of higher precipitation. This is followed by a decline in C:N and a rise in TOC in the second partwhich indicates an increase of primary production in the lake. In the third part we again see a shift inthe C:N indicating a source change back to more terrestrial runoff. The increase in TOC and LOIvalues together with decrease in C:N ratio and a steady increase in δ13C indicate an increase inlacustrine productivity in the upper part of the core.By reconstructing the palaeoenvironmental history in Bolgoda Lake we can conclude that it isprobable that some other factor than diagenetic change affects the lake. Our results indicate thatthese changes most likely are due to more wet periods and anthropogenic activity, mainly throughland use changes.