River metamorphosis and environmental change in the Macdonald Valley,New South Wales,since 1949

A significant metamorphosis of channel form occurred on the lower Macdonald River between 1949 and 1955; width and width-depth ratio increased and depth, sinuosity and weighted mean per cent silt-clay in the channel perimeter decreased. The channel has remained unstable since 1955, exhibiting frequent variations in bed elevation and a recent period of minor channel contraction followed by slight enlargement. Since 1946 there has been an increase in summer and annual rainfall and an abrupt, upward shift of the annual series flood frequency curve. As a result an increased proportion of the total sediment load of the river is now being transported as bed-material load. The change in sediment load is a result of greater stream competence and the consequent reworking of sandy sediment temporarily stored within the channel as benches. The observed channel changes are a quasi-adjustment to the increased flood and bed-material load discharges.     

Fire and its roles in early hominid lifeways

Discovery of the uses and later the invention of fire-making are fundamental to humanity. Following reports over the last decade of traces of fire found on Lower Pleistocene archaeological sites in eastern Africa, the dating of the control of fire by hominids has become a controversial issue. In this paper we critically review the contexts and, in the light of a battery of archaeometric techniques, the nature of reported instances of fire from Koobi Fora and Chesowanja in Kenya, and from Gadeb and the Middle Awash in Ethiopia. We conclude with a discussion of the roles fire may have played in the lifeways of early Pleistocene savanna-living hominids.

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Résumé La découverte des usages du feu et ensuite de sa préparation est fondamentale pour l'humanité. Suite à des rapports au cours de la dernière décennie signalant des traces de feu relevées dans des sites archéologiques du Pléistocène inférieur dans l'est de l'Afrique, la datation du contrôle du feu par les hominiens est devenu une source de controverse. Dans cet article, nous révisons d'un oeil critique les contextes et la nature des cas de feu signalés à Koobi Fora et à Chesowanja au Kenya, et à Gadeb et dans l'Awash moyen en Éthiopie, à la lumière d'une suite de techniques archéometriques. Suit en conclusion une discussion sur les rôles qu'aurait pu jouer le feu dans les modes de vie des hominiens vivant dans les savannes du Pléistocène inférieur.