Papers by Tamara J . J . Vernimmen
Schriften des Forschungszentrums Jülich, Reihe Umwelt Vol. 44, p. 139 - 146, 2003
Between AD 1500 and 1700, in The Netherlands high-quality art and furniture was produced.
The que... more Between AD 1500 and 1700, in The Netherlands high-quality art and furniture was produced.
The question of the historical meaning of these pieces is, among others, related to their exact
age. Dendrochronology can contribute to the determination of their creation dates; usong
cross-dating techniques, we can determine the calendar years during which the oak trees
used for pieces of art and furniture were felled. Such dates provide a terminus post quem for
the creation of these pieces. In addition, dendrochronology can be used to identify the
provenance of the wood.
International Biodeterioration & Biodegradation, 2008
In this study, we investigated whether dendrochronology can be used to determine the felling date... more In this study, we investigated whether dendrochronology can be used to determine the felling dates and origen of the trees that were used as wooden pile foundations under historic buildings. Dating and dendroprovenancing of the timber was possible for eight out of nine buildings. This is due mainly to the availability of newly constructed tree-ring chronologies of pine for the Netherlands and was of particular value in three of the investigated buildings where local timber had been used. Problems with the analysis of short time series from local timber are discussed. Detection of the felling date and origen of the trees used as piles allowed determination of the time lag between felling of the tree and implementation of the timber. Any possible effects of storage and/or transportation time on the susceptibility of the timber to bacterial degradation are considered.
SUPPLYING THE ROMAN EMPIRE LIMES XXV, 2024
During an excavation in the periphery of a native settlement near Houten, the Netherlands, only a... more During an excavation in the periphery of a native settlement near Houten, the Netherlands, only a few Roman (1st-2nd century AD) ditches and a well were unearthed. At the bottom of the well however, an interesting discovery was made: a layer of thin wooden planks scattered all over the bottom and clearly dumped as waste. Due to the fragile state of the planks, the complete section of soil was dug out to be uncovered indoors under more controlled circumstances, thereby revealing 29 more or less complete planks. They measured up to 1 m in length and between 12 and 18 cm in width. Most remarkable however is their slight thickness: only 1 to 8 mm. Almost all planks have a pointed end and a small hole in the middle of the other end. All planks were identified as oak and several planks were dated between 88 and 147 AD using dendrochronology.
The dimensions and the shape of the planks as well as the presence of nail holes brought us to the interpretation as roof shingles or scandulas. Roof shingles from Roman times are occasionally being found in Europe. The shingles from Houten appear to be the first ones from a native, i.e. non-urban or non-military context. An inventory of similar finds gave us insight into the production and use of roof shingles in general during Roman times as well as a clue to the long trip the shingles from Houten have made before ending up at the bottom of a well.
SUPPLYING THE ROMAN EMPIRE LIMES XXV, 2024
Among the well-preserved wood finds from Weerdkampen (124-315 A.D.), a vicus located near the Lim... more Among the well-preserved wood finds from Weerdkampen (124-315 A.D.), a vicus located near the Limes at Valkenburg North-Holland, are two finds that really stand out: turned pieces of an oak and boxwood bed. Allthough the wood may be imported, the style of this furniture does not breathe ‘Rome’.
Computer Methods in Biomechanics and Biomedical Engineering, 2011
In the light of the currently increasing drought frequency and water scarcity on oceanic islands,... more In the light of the currently increasing drought frequency and water scarcity on oceanic islands, it is crucial for the conservation of threatened insular vertebrates to assess how they will be affected. A 4000 yr old fossil assemblage in the Mare Aux Songes (MAS), southwest Mauritius, Mascarene Islands, contains bones of 100 000+ individual vertebrates, dominated by two species of giant tortoises Cylindraspis triserrata and C. inepta, the dodo Raphus cucullatus, and 20 other vertebrate species Mid-Holocene vertebrate bone Concentration-Lagerstätte on oceanic island Mauritius provides a window into the ecosystem of the dodo (Raphus cucullatus). Quaternary Science Reviews 28: 14-24). Nine radiocarbon dates of bones statistically overlap and suggest mass mortality occurred between 4235 and 4100 cal. yr BP. The mortality period coincides with a widely recognized megadrought event. Our multidisciplinary investigations combining geological, paleontological and hydrological evidence suggests the lake was located in a dry coastal setting and had desiccated during this period. Oxygen isotope data from a Uranium-series dated stalagmite from Rodrigues, an island 560 km east of Mauritius, supports this scenario by showing frequently alternating dry and wet periods lasting for decades between 4122 and 2260 cal. yr BP. An extreme drought resulted in falling water-tables at MAS and elsewhere on the island, perhaps deprived these insular vertebrates of fresh water, which led to natural mass mortalities and possibly to extirpations. In spite of these events, all insular species survived until at least the seventeenth century, confirming their resistance to climatic extremes. Despite this, the generally exponential increase of combined human impacts on islands including loss of geodiversity, habitats, and stocks of fresh water, there will be less environmental safe-haven options for insular endemic and native vertebrates during future megadrought conditions; and therefore will be more prone to extinction.
The Holocene, 2015
Analyses of pollen, diatoms, XRF geochemistry, and pigments provide a unique window into how an i... more Analyses of pollen, diatoms, XRF geochemistry, and pigments provide a unique window into how an insular ecosystem in Mauritius responded to an extreme drought event 4200 years ago. We provide a reconstruction of regional vegetation change and local wetland development under influence of sea level rise and inferred climate change between 4400 and 4100 cal. yr BP. Our multi-proxy data evidence a severe drought between 4190 and 4130 cal. yr BP, which ultimately led to mass mortality of larger vertebrates, including two species of giant tortoises and dodos in a <2-ha region. This prolonged drought around the Indian Ocean is recorded in many regions dependent on monsoon precipitation and is suggested to cause the collapse of human societies in East Africa and India. We demonstrate a direct relation between the mass mortality events in the Mare aux Songes (MAS) rock valley and the 4200 cal. yr BP drought. MAS represents a fresh water source that attracted and concentrated vertebrates. Abrupt increased aridity induced regional fires on Mauritius and caused decreased water levels, and a shrinking water surface resulting in further concentration of the animals in this coastal site. Upconing of the saline wedge underlying the fresh water source induced progressive salinization. The excrements of the animals produced hypertrophic conditions that, combined with salinization and high temperatures, created a suitable environment for potentially toxic cyanobacteria. These factors led to a deadly cocktail, resulting in the death of 100,000s of vertebrates by intoxication, dehydration, trampling, and miring, and promoted a unique conservation of fossils. The '4.2 ka megadrought' likely induced similar bottlenecks elsewhere in the SW Indian Ocean region.
Quaternary Science Reviews, 2009
Although the recent history of human colonisation and impact on Mauritius is well documented, vir... more Although the recent history of human colonisation and impact on Mauritius is well documented, virtually no records of the pre-human native ecosystem exist, making it difficult to assess the magnitude of the changes brought about by human settlement. Here, we describe a 4000-year-old fossil bed at Mare aux Songes (MAS) in south-eastern Mauritius that contains both macrofossils (vertebrate fauna, gastropods, insects and flora) and microfossils (diatoms, pollen, spores and phytoliths). With >250 bone fragments/m 2 and comprising 50% of all known extinct and extant vertebrate species (n s ¼ 44) of Mauritius, MAS may constitute the first Holocene vertebrate bone Concentration-Lagerstä tte identified on an oceanic volcanic island. Fossil remains are dominated by extinct giant tortoises Cylindraspis spp. (63%), passerines (w10%), small bats (7.8%) and dodo Raphus cucullatus (7.1%). Twelve radiocarbon ages [four of them duplicates] from bones and other material suggest that accumulation of fossils took place within several centuries. An exceptional combination of abiotic conditions led to preservation of bones, bone collagen, plant tissue and microfossils. Although bone collagen is well preserved, DNA from dodo and other Mauritian vertebrates has proved difficult. Our analysis suggests that from ca 4000 years ago (4 ka), rising sea levels created a freshwater lake at MAS, generating an oasis in an otherwise dry environment which attracted a diverse vertebrate fauna. Subsequent aridification in the south-west Indian Ocean region may have increased carcass accumulation during droughts, contributing to the exceptionally high fossil concentration. The abundance of floral and faunal remains in this Lagerstä tte offers a unique opportunity to reconstruct a pre-human ecosystem on an oceanic island, providing a key foundation for assessing the vulnerability of island ecosystems to human impact.
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Papers by Tamara J . J . Vernimmen
The question of the historical meaning of these pieces is, among others, related to their exact
age. Dendrochronology can contribute to the determination of their creation dates; usong
cross-dating techniques, we can determine the calendar years during which the oak trees
used for pieces of art and furniture were felled. Such dates provide a terminus post quem for
the creation of these pieces. In addition, dendrochronology can be used to identify the
provenance of the wood.
The dimensions and the shape of the planks as well as the presence of nail holes brought us to the interpretation as roof shingles or scandulas. Roof shingles from Roman times are occasionally being found in Europe. The shingles from Houten appear to be the first ones from a native, i.e. non-urban or non-military context. An inventory of similar finds gave us insight into the production and use of roof shingles in general during Roman times as well as a clue to the long trip the shingles from Houten have made before ending up at the bottom of a well.
The question of the historical meaning of these pieces is, among others, related to their exact
age. Dendrochronology can contribute to the determination of their creation dates; usong
cross-dating techniques, we can determine the calendar years during which the oak trees
used for pieces of art and furniture were felled. Such dates provide a terminus post quem for
the creation of these pieces. In addition, dendrochronology can be used to identify the
provenance of the wood.
The dimensions and the shape of the planks as well as the presence of nail holes brought us to the interpretation as roof shingles or scandulas. Roof shingles from Roman times are occasionally being found in Europe. The shingles from Houten appear to be the first ones from a native, i.e. non-urban or non-military context. An inventory of similar finds gave us insight into the production and use of roof shingles in general during Roman times as well as a clue to the long trip the shingles from Houten have made before ending up at the bottom of a well.