Microscopic Charcoal Signal in Archaeological Contexts

Author(s):  
Laurent Marquer ◽  
Thierry Otto
Keyword(s):  
2000 ◽  
Vol 54 (1) ◽  
pp. 81-89 ◽  
Author(s):  
Patricio I. Moreno

A pollen record from Lago Condorito (41°45′S, 73°07′W) shows that North Patagonian Rain Forest taxa predominated between about 13,000 and 12,200 14C yr B.P. in the lowlands of southern Chile, near the city of Puerto Montt. This was followed by the expansion and persistence of the conifer Podocarpus nubigena between 12,200 and 9900 14C yr B.P. Trees favored by disturbance expanded between 11,200 and 9900 14C yr B.P., concurrent with sharp and sustained increases of microscopic charcoal particles. Taxa of low-elevation rain forests expanded and became more diverse in pulses centered at 9900 and 9000 14C yr B.P., following the disappearance of P. nubigena. These data suggest conditions approaching modern climate between about 13,000 and 12,200 14C yr B.P. The climate cooled between 12,200 and 9900 14C yr B.P., then quickly warmed to interglacial conditions. Stand-replacing fires occurred near Lago Condorito between 11,200 and 9900 14C yr B.P., under cool-temperate, humid conditions. The proximity and reported antiquity of the Monte Verde archeological site raise the possibility that these fires were set by human activities.


2021 ◽  
Author(s):  
◽  
Pamela I Chester

<p>Palynological investigations aimed at reconstructing the vegetation history of the Grevena Province, northwestern Greece were conducted in association with an archaeological research project. Fossil pollen, spores, microscopic charcoal particles, and sediment stratigraphies of radiocarbon-dated sediment cores from three sites in pine, beech, and oak woodland zones provide evidence of climatic changes, land use, and erosion during the last 3500 years. Identification of pollen and spores was aided by an extensive reference collection of local species and construction of a pollen key modelled on that of Faegri & Iversen (1989). Extant vegetation units are characterized by their contemporary pollen assemblages. Surface samples collected along an elevational transect show that a fairly direct relationship exists between the major vegetation zones and pollen deposition: pine, beech, and oak pollen predominate in their respective zones. Over-representation of pine pollen is notable. The sequence from Gomara site in the pine wood-pasture zone at 1750 m asl covers the time span c. 1340 BC to 700 AD. A local open pine wood was gradually replaced by beech after c. 890 BC, perhaps through reduced disturbance and/or increased precipitation. A herbaceous pollen spike at c. 80 BC resulted from deposition of volcanic ash. Pine wood replaced beech at c. 330 AD. Two periods of accelerated erosion coincide with the pine wood phases and with anthropogenic burning and grazing. These periods are separated by a period of abandonment when the climate was probably wetter. The sequence from Anelia site in the beech wood zone at 1440 m asl spans c. 1560-1989 AD. The site was surrounded by beech wood for the duration of the sequence. Regional and local burning of vegetation is indicated by an abundance of microscopic charcoal particles from c. 1560 until c. 1730 AD, when it ceased. Periods of erosion occurred during this period. After c. 1730 AD a homogeneous peat formed on the wetland, suggesting a period of greater landscape stability. From pollen evidence, a variety of land-use practices such as cereal cultivation, grazing, coppicing, and lumbering were carried out in the vicinity of the site especially before c. 1730 AD, but these diminished after 1920 AD. The lower part of the sequence from Kellia site in the oak wood-steppe zone at 580 m asl is insecurely dated, but the upper part spans c. 1230-1989 AD. The lowlands were covered with deciduous/semi-evergreen oak woods for the duration of the sequence. Since c. 1230 AD land close to the site was intensively cultivated with a variety of cereals. Burning occurred frequently throughout the period. The ratio of deciduous to semi-evergreen oak pollen is correlated with temperature and indicates a decline from c. 1230-1680 AD, after which temperature increased, a pattern similar to that of the Little Ice Age. Frontispiece The cultural landscape of Grevena Province looking NE towards the Vourinos Mountains on the eastern border of Grevena, from a prominent hill about 1 1/4 km NW of the modern village of Itea. In the foreground is the stubble of a wheat field. Beyond is an 18th century church dedicated to Aghia Panaghia. The middle ground is the steppe oak wood pasture of Grevena plains. Recent erosion on the sides of gullies can be seen here, even though they appear to be well vegetated. Frescoes in the church are shown in the enlargement. It stands on a registered archaeological site, Grevena Project 108 (21 degrees 36.18' E, 40 degrees 04.29' N, 640 m asl) that covers more than 10,000 m2. Archaeological evidence dating to Early Iron Age, Archaic, Classical, Hellenistic, Roman, Early Medieval and Ottoman periods has been recorded.</p>


2021 ◽  
Author(s):  
◽  
Pamela I Chester

<p>Palynological investigations aimed at reconstructing the vegetation history of the Grevena Province, northwestern Greece were conducted in association with an archaeological research project. Fossil pollen, spores, microscopic charcoal particles, and sediment stratigraphies of radiocarbon-dated sediment cores from three sites in pine, beech, and oak woodland zones provide evidence of climatic changes, land use, and erosion during the last 3500 years. Identification of pollen and spores was aided by an extensive reference collection of local species and construction of a pollen key modelled on that of Faegri & Iversen (1989). Extant vegetation units are characterized by their contemporary pollen assemblages. Surface samples collected along an elevational transect show that a fairly direct relationship exists between the major vegetation zones and pollen deposition: pine, beech, and oak pollen predominate in their respective zones. Over-representation of pine pollen is notable. The sequence from Gomara site in the pine wood-pasture zone at 1750 m asl covers the time span c. 1340 BC to 700 AD. A local open pine wood was gradually replaced by beech after c. 890 BC, perhaps through reduced disturbance and/or increased precipitation. A herbaceous pollen spike at c. 80 BC resulted from deposition of volcanic ash. Pine wood replaced beech at c. 330 AD. Two periods of accelerated erosion coincide with the pine wood phases and with anthropogenic burning and grazing. These periods are separated by a period of abandonment when the climate was probably wetter. The sequence from Anelia site in the beech wood zone at 1440 m asl spans c. 1560-1989 AD. The site was surrounded by beech wood for the duration of the sequence. Regional and local burning of vegetation is indicated by an abundance of microscopic charcoal particles from c. 1560 until c. 1730 AD, when it ceased. Periods of erosion occurred during this period. After c. 1730 AD a homogeneous peat formed on the wetland, suggesting a period of greater landscape stability. From pollen evidence, a variety of land-use practices such as cereal cultivation, grazing, coppicing, and lumbering were carried out in the vicinity of the site especially before c. 1730 AD, but these diminished after 1920 AD. The lower part of the sequence from Kellia site in the oak wood-steppe zone at 580 m asl is insecurely dated, but the upper part spans c. 1230-1989 AD. The lowlands were covered with deciduous/semi-evergreen oak woods for the duration of the sequence. Since c. 1230 AD land close to the site was intensively cultivated with a variety of cereals. Burning occurred frequently throughout the period. The ratio of deciduous to semi-evergreen oak pollen is correlated with temperature and indicates a decline from c. 1230-1680 AD, after which temperature increased, a pattern similar to that of the Little Ice Age. Frontispiece The cultural landscape of Grevena Province looking NE towards the Vourinos Mountains on the eastern border of Grevena, from a prominent hill about 1 1/4 km NW of the modern village of Itea. In the foreground is the stubble of a wheat field. Beyond is an 18th century church dedicated to Aghia Panaghia. The middle ground is the steppe oak wood pasture of Grevena plains. Recent erosion on the sides of gullies can be seen here, even though they appear to be well vegetated. Frescoes in the church are shown in the enlargement. It stands on a registered archaeological site, Grevena Project 108 (21 degrees 36.18' E, 40 degrees 04.29' N, 640 m asl) that covers more than 10,000 m2. Archaeological evidence dating to Early Iron Age, Archaic, Classical, Hellenistic, Roman, Early Medieval and Ottoman periods has been recorded.</p>


2020 ◽  
Author(s):  
Dimitri Osmont ◽  
Sandra Brugger ◽  
Anina Gilgen ◽  
Helga Weber ◽  
Michael Sigl ◽  
...  

Abstract. Recent large wildfires, such as those in Portugal in 2017, have devastating impacts on societies, economy, ecosystems and environments. However, wildfires are a natural phenomenon, which has been exacerbated by land use during the past millennia. Ice cores are one of the archives preserving information on fire occurrences over these timescales. A difficulty is that emission sensitivity of ice cores is often unknown, which constitutes a source of uncertainty in the interpretation of such archives. Information from specific and well-documented case studies is therefore useful to better understand the spatial representation of ice-core burning records. The wildfires near Pedrógão Grande in Central Portugal in 2017 provided a test bed to link a fire event to its footprint left in a high-alpine snowpack considered a surrogate for high-alpine ice-core sites. Here, we (1) analyzed black carbon (BC) and microscopic charcoal particles deposited in the snowpack close to the high-alpine research station Jungfraujoch in the Swiss Alps, (2) calculated backward trajectories based on ERA-Interim reanalysis data and simulated the transport of these carbonaceous particles using a global aerosol-climate model, and (3) analyzed the fire spread, its spatial and temporal extent, as well as its intensity, with remote sensing (e.g. MODIS) active fire and burned area products. A peak of atmospheric equivalent BC (eBC) observed at the Jungfraujoch research station on 22nd June, with elevated eBC levels until the 25th June, is in correspondence with a peak in refractory BC (rBC) and microscopic charcoal observed in the snow layer. rBC was mainly scavenged by wet deposition and we obtained scavenging ratios ranging from 81 to 91. Unlike for microscopic charcoal, the model did not well reproduce the observed rBC signal. Our study reveals that microscopic charcoal can be transported over long distances (1500 km), and that snow and ice archives are much more sensitive to distant events than sedimentary archives, for which the signal is dominated by local fires. Microscopic charcoal concentrations were exceptionally high since this single outstanding event deposited as many charcoal particles per day as during an average year in ice cores. This study unambiguously links the fire tracers in the snow with the highly intensive fires in Portugal, where a total burned area of 501 km2 was observed on the basis of satellite fire products. According to our simulations, this fire event emitted at least 203.5 tons of BC.


2000 ◽  
Vol 164 (1-4) ◽  
pp. 247-262 ◽  
Author(s):  
Kevin J. Edwards ◽  
Graeme Whittington ◽  
Richard Tipping

Sign in / Sign up

Export Citation Format

Share Document