Abstract
LONDON. Geological Society, Mar. 20.-Sir Douglas Mawson: Some South Australian algal limestones in process of formation. A record of three different types of limestone, now actually in process of formation under the influence of plant-growth, occurring in the southeastern region of South Australia. In each of the localities examined, whether inundated in winter only or permanently inundated, the formation of limestone is being determined by blue-green algae.-Arthur W. Groves: The unroofing of the Dartmoor granite, and an outline of the distribution of its detritus in the sediments of southern England. A systematic outline mineralogical survey has been made of the sediments of southern England, from the base of the Permian in Devon (Watcombe Clay) up to the Lenham Beds of the North Downs. The minor intrusions above the granite were being rapidly eroded in Permo-Triassic times, but there is no evidence of the actual granite being exposed at that period. No proof has been obtained of direct derivation of detritus from theDartmoor granite in the Jurassic rocks. The earliest evidence of the exposure of the granite is in late Wealden times. Throughout Upper Cretaceous times-particularly during the Selbornian epoch-the Dartmoor granite contributed enormous quantities of detritus to the sediments of southern England, reaching as far afield as Kent and Oxfordshire, and perhaps farther. The Cornish Pliocene was largely derived from the Cornish granites. The St. Keverne outlier is mainly derived from the Falmouth and Bodmin masses, and yields no evidence of Dartmoor detritus. A number of new occurrences of dumortierite are recorded.
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Societies and Academies. Nature 123, 625–627 (1929). https://doi.org/10.1038/123625b0
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DOI: https://doi.org/10.1038/123625b0