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Three continuous terrestrial high-resolution palaeoenvironmental records for the Late-glacial and the Holocene have been reconstructed for different ecosystems in Fuego-Patagonia on a longitudinal transect at latitude 53°S. The records describe the nature and extent of environmental and climatic changes inferred from palynological evidence supported by lithostratigraphy, tephrochronology and radiocarbon dating. The environmental changes recorded at the three sites displays a significant degree of synchrony in response to similar large-scale climatic changes. Clear stratigraphical evidence alongside the pollen record indicates a shift to warmer interstadial conditions between c. 14,800 Cal yr BP and 14,400 Cal yrs BP. During the period coeval with ACR the vegetation was dominated by cold resistant dry land herbs such as Poaceae, Asteraceae (Suf. Asteroideae) and Acaena, by c. 13,200 Cal yr BP the vegetation changed from the dominance of cold resistant dry land herbs towards more mesic conditions and the expansion of steppe dominated by Poaceae with patches of Nothofagus forest. The establishment of the forest and an eastward shift of the forest-steppe ecotone by c. 12,500 Cal yr BP from which a gradual shift from colder to warmer conditions and the relatively stronger influences of the SSWs is inferred. The sequence of Late-glacial environmental changes places Fuego-Patagonia within the new palaeoecological data provided by this study includes “the earliest” evidence for the establishment of subantarctic Nothofagus forest during the LGIT in Fuego-Patagonia. During the Early-Holocene two major phases of Nothofagus forest expansion were registered between c. 11,700 - 10,500 Cal yr BP and c. 9,500 - 8,200 Cal yr BP. These intervals of expansion of Nothofagus forest are separated by an interval of forest contraction in response to lower effective moisture between c. 10,500 - 9,500 Cal yr BP. An intense arid phase is inferred between c. 8,250 Cal yr BP and 6,800 Cal yr BP and probably leading to an increase in the amount of dry fuel available during the mid-Holocene in Fuego-Patagonia leading to the highest fire activity promoted by very weak SSWs at this time. The later Holocene was characterised by an increase in humidity and an inferred intensification of the SSWs.

The study of Holocene climate change is vital to understanding present and future climate conditions in the Upper Midwest region of the United States. Varved sediments from Elk Lake, Clearwater County, Minnesota provide an archive of multiple climate sensitive proxies and past climate conditions, particularly related to the balance of precipitation and evaporation (available moisture) for the North Central United States. Studies conducted in the past using Elk Lake sediments have established large scale and long term changes in the climate history of the region, but were done at a resolution that only allowed for a discussion of events on time scales of hundreds to thousands of years. Scanning XRF is a new analytical technique that allows for much higher resolution, geochemical data to be gathered from sediment cores for the characterization of climate variability with resolution on the order of decades to inter-annual changes. This study seeks to repeat, using new analytical and higher resolution methods, the work done by previous researchers. One centimeter resolution XRF scans were used to describe changes that occurred during the Holocene, and 200 micron scans were used to identify the nature of varve deposition during major periods in the Holocene and to characterize the timing and relationships between the laminations that make up individual varves. With higher resolution data with which to work, time series analysis provides insight into high frequency cycles during the Holocene record including El Nino Southern Oscillation (ENSO) and solar activity cycles. With the addition of the first known geophysical data set from Elk Lake, this study also illustrates the usefulness of obtaining multiple records from an individual lake. Through the use of both geochemical and geophysical data, it is shown that events seen separately in each data set can be correlated to one another and an accurate estimate for the timing of major climate events can be obtained.