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Pollen and diatom analyses of organic sediments from Three-Quarter Mile Lake, a perched lake on Cape York Peninsula, north Queensland, indicate that significant changes in vegetation and hydrology occurred during the Holocene. Early Holocene grass-dominated landscapes were replaced in mid-Holocene times by increasingly woody vegetation comprising tropical heathlands, savanna and rainforest. Early-Holocene lake levels fluctuated widely. From mid-Holocene times, lake levels stabilized and water became increasingly acidic as a mature swamp forest developed adjacent to the lake and contributed tannins to the lake water. The timing and character of changes are consistent with those described from the Atherton Tableland in wet tropical Queensland. Holocene dry phases described from the Northern Territory and the western shores of Cape York cannot be identified from Three-Quarter Mile Lake. Rainforest is currently close to its greatest Holocene extent, suggesting that the rainforest-dependent endemic fauna of northern Cape York have been isolated from rainforest blocks to the south throughout the last 10 000 years and, by inference, throughout at least the 120 000 years beyond that. [ABSTRACT FROM AUTHOR]