Folia dendrologica

This chapter provides researchers with a guide to some of the types of dating techniques that can be used in geomorpological investigations and issues that need to be addressed when using gechronological data, specifically issues relating to accuracy and precision. This chapter also introduces the 'types' of dating methods that are commonly used in geomorphological studies. This includes sidereal, isotopic, radiogenic, and chemical dating methods

New age estimates for the Palaeolithic assemblages and Pleistocene succession of Casablanca, Morocco

Marine and aeolian Quaternary sediments from Casablanca, Morocco were dated using the optically stimulated luminescence (OSL) signal of quartz grains. These sediments form part of an extensive succession spanning the Pleistocene, and contain a rich faunal and archaeological record, including an Acheulian lithic assemblage from before the Brunhes–Matayama boundary, and a Homo erectus jaw from younger cave deposits. Sediment samples from the sites of Reddad Ben Ali, Oulad J’mel, Sidi Abderhamane and Thomas Quarries have been dated, in order to assess the upper limits of OSL. The revision of previously measured mammalian tooth enamel electron spin resonance (ESR) dates from the Grotte des Rhinocéros, Oulad Hamida Quarry 1, incorporating updated environmental dose rate measurements and attenuation calculations, also provide chronological constraint for the archaeological material preserved at Thomas Quarries. Several OSL age estimates extend back to around 500,000 years, with a single sample providing an OSL age close to 1 Ma in magnetically reversed sediments. These luminescence dates are some of the oldest determined, and their reliability is assessed using both internal criteria based on stratigraphic consistency, and external lithostratigraphic, morphostratigraphic and independent chronological constraints. For most samples, good internal agreement is observed using single aliquot regenerative-dose OSL measurements, while multiple aliquot additive-dose measurements generally have poorer resolution and consistency. Novel slow-component and component-resolved OSL approaches applied to four samples provide significantly enhanced dating precision, and an examination of the degree of signal zeroing at deposition. A comparison of the OSL age estimates with the updated ESR dates and one U-series date demonstrate that this method has great potential for providing reliable age estimates for sediments of this antiquity. We consider the cause of some slight age inversion observed at Thomas Quarries, and provide recommendations for further luminescence dating within this succession

First discovery of Pleistocene orangutan (Pongo sp.) fossils in Peninsular Malaysia: Biogeographic and paleoenvironmental implications

Nine isolated fossil Pongo teeth from two cave sites in Peninsular Malaysia are reported. These are the first fossil Pongo specimens recorded in Peninsular Malaysia and represent significant southward extensions of the ancient Southeast Asian continental range of fossil Pongo during two key periods of the Quaternary. These new records from Peninsular Malaysia show that ancestral Pongo successfully passed the major biogeographical divide between mainland continental Southeast Asia and the Sunda subregion before 500ka (thousand years ago).If the presence of Pongo remains in fossil assemblages indicates prevailing forest habitat, then the persistence of Pongo at Batu Caves until 60ka implies that during the Last Glacial Phase sufficient forest cover persisted in the west coast plain of what is now Peninsular Malaysia at least ten millennia after a presumed corridor of desiccation had extended to central and east Java. Ultimately, environmental conditions of the peninsula during the Last Glacial Maximum evidently became inhospitable for Pongo, causing local extinction. Following post-glacial climatic amelioration and reforestation, a renewed sea barrier prevented re-colonization from the rainforest refugium in Sumatra, accounting for the present day absence of Pongo in apparently hospitable lowland evergreen rainforest of Peninsular Malaysia. The new teeth provide further evidence that Pongo did not undergo a consistent trend toward dental size reduction over time

Establishing the time of initial human occupation of Liang Bua, western Flores, Indonesia

Liang Bua, a limestone cave in western Flores, has an archaeological and faunal sequence known to span the last 95 ka and is the type-site for a small-bodied hominid species, Homo floresiensis. This paper describes the geomorphic history of this significant site, and presents numerical ages for key events as determined by thermo luminescence dating of sediments (using a dual-aliquot regenerative-dose protocol) and uranium-series dating of flowstones. Our age estimates indicate that Liang Bua existed as a subterranean chamber by 400 ka ago. It was subsequently exposed by the incision of the Wae Racang River, which invaded the cave around 190 ka and deposited an upward-fining sequence of water-rolled boulders and cobbles. The latter conglomerate was partially reworked around 130 ka ago and was capped by flowstones at 100 ka. The conglomerate also contains stone artefacts, which implies that the occupation of the surrounding area is at least as old as the time of emplacement of the conglomerate. After 190 ka, a complex sequence of erosion and deposition led to the accumulation of at least 11 m of sediment in the front chamber of the cave, which proved suitable for hominid occupation. Such geochronological and geomorphological information is extremely valuable for interpreting the archaeological record at Liang Bua and its wider significance. (c) 2006 Elsevier Ltd. All rights reserved