This paper discusses the approach used to identify the most relevant chronological information on the historic development of the abandoned site of AlUla Old Town, in the northwest of the Kingdom of Saudi Arabia (Western Asia). The approach is based on the use of the radiocarbon method to date earth mortars samples and soil layers used to create the constructive sequence of some buildings and, in turn, the chronological evolution of the site. Eleven samples of organic material (i.e., charcoal and vegetable fibers) were carefully removed from mortar samples and soil levels from six buildings and structures in the northern and southern areas of the town. Buildings and soil layers were chosen for their stratigraphic relevance and conservation conditions, based on an initial archaeological analysis of both, buildings and underground structures. Laboratory-based mortar analysis led to the characterization of the mortar’s inorganic fraction, and to the isolation of the organic material for the radiocarbon dating. Results from the accelerator mass spectrometry (AMS) laboratory provides evidence of a Late Mamluk/Early Ottoman constructive phase (i.e., 15th–17th c. AD) of the Old Town that was only partially known until very recently. Furthermore, the results allowed the identification of an Ottoman phase (i.e., 17th–19th c. AD) during which most of the buildings and structures were rebuilt, and of a Late Ottoman phase (i.e., 19th–20th c. AD) representing the most recent interventions before the end of the Ottoman occupation of the area.

The sorption of 8-hydroxyquinoline onto some clays and oxides was studied as a function of concentration, pH, and time. The sorption reaction reached equilibrium in about 5 hr, was irreversible, and reached a maximum at pH 5. The decrease in sorption on both sides of the maximum was attributed to electrostatic interactions of charged molecules with similarly charged surfaces and/or neighbors as well as solvent and proton competition. X-ray powder diffraction of dried clays showed that a one-layer complex formed in which the molecules lay flat between the clay interlayers. The sorption onto the clays included physical and exchange sorption and was accompanied by exchangeable cation hydrolysis. At high surface coverage the silicate structure deteriorated in the direction of the Z-axis due to chemical aggressiveness of the reagent.

Collaborative autoethnography can function as a means of reclaiming certain African realities that have been co-opted by colonial epistemes and language. This can be significant in very concrete ways: northern Uganda is suffering a catastrophic loss of tree cover, much of which is taking place on the collective family landholdings that academia and the development sector have categorized as “customary land.” A collaboration by ten members of such landholding families, known as the Acholi Land Lab, explores what “customary ownership” means to them and their relatives, with a view to understanding what may be involved in promoting sustainable domestic use of natural resources, including trees.

Evidence for the formation of maghemite from goethite due to a bushfire on acid sulfate soil at East Trinity, Australia, is presented. Oxidation of pyrite-bearing acid sulfate soils led to precipitation of goethite-impregnated leaf litter. During a major bushfire, goethite with a crystal size calculated from broadening of the 110 reflection of ∼9 nm was converted to microcrystalline maghemite (size 12 nm, 220 reflection) and hematite (17 nm, 104 reflection) in a matrix of partly combusted plant litter. Replication of this natural formation of maghemite from goethite was achieved in the laboratory by burning goethite-impregnated leaf litter.

Radiocarbon dates on charred plant remains are often used to define the chronology of archives such as lake cores and fluvial sequences. However, charcoal is often older than its depositional context because old-wood can be burnt and a range of transport and storage stages exist between the woodland and stream or lake bed (“inherited age”). In 1978, Blong and Gillespie dated four size fractions of charcoal found floating or saltating in the Macdonald River, Australia. They found larger fragments gave younger age estimates, raising the possibility that taphonomic modifications could help identify the youngest fragments. In 1978 each date required 1000s charcoal fragments. This study returns to a sample from the Macdonald River to date individual charcoal fragments and finds the inherited age may be more than 1700 years (mode 250 years) older than the collection date. Taphonomic factors, e.g., size, shape or fungal infestation cannot identify the youngest fragments. Only two fragments on short-lived materials correctly estimated the date of collection. In SE Australia, this study suggests that wood charcoal will overestimate the age of deposition, taphonomic modifications cannot be used to identify which are youngest, and multiple short-lived materials are required to accurately estimate the deposition age.

The Palaeocene–Eocene Thermal Maximum (PETM) was a global extreme climatic event, but it is relatively unknown from lower latitudes or equatorial regions in comparison to mid- and high latitudes. The present study provides the first clay mineralogical evidence of the PETM and subsequent hyperthermal events in a near-equatorial region represented by the Akli Formation in the Barmer Basin, India. The 32 m-thick succession of the Akli Formation shows abrupt changes in smectite and kaolin abundances preceding, during and succeeding the PETM event. Within the studied section, the kaolin content increases from 5–8% pre-PETM to 30–35% during the PETM, and then again decreases to 5–6% during the post-PETM period. The smectite, however, is marked by a corresponding decrease and its transformation into kaolin in acid weathering conditions. The transformation of the smectite is first marked by hydroxy interlayering and then transformation into kaolin during the PETM. The transformation of smectite into kaolin also resulted in extensive precipitation of iron oxide in sediments. The clay mineralogical changes in the Palaeocene–Eocene transition sediments of the Akli Formation were caused by 3–5°C warming and a 25–50% increase in rainfall during the hyperthermal events. Unusually high charcoal (~20%) fragments during the Palaeocene–Eocene transition also suggest warming and widespread biomass burning during the PETM in the lower latitudes.

The timeframes of Holocene anthropogenic dune remobilization in Central Europe remain less studied compared to those of Late Glacial climatically controlled dune formation. The present contribution aims to reinforce existing knowledge on the chronology of Late Glacial–Holocene dune activity and stability, as well as to reveal the scale of human impact on dune remobilization. Accelerator mass spectrometry radiocarbon (AMS 14C) dating and calibration of the results are reported from paleosol horizons buried in inland dune deposits that occur in Central and Eastern Poland. Twenty-three new dates are based on charcoal samples collected at 13 sites. From each of the investigated sites, at least one AD date is obtained, indicating that buried paleosols of such young age are far more widespread in Polish dunes than reflected in previous studies. The widespread preservation of these paleosols under cover of aeolian sand reflects the extent of the anthropogenic dune formation phase that peaked during the Medieval and Early Modern periods.

Pollen preserved in caves provides a little-appreciated opportunity to study past vegetation and climate changes in regions where conventional wetland sediments are either unavailable, contain little organic matter, and/or are difficult to date accurately. Most palynology in caves has focused on clastic infill sediments, but pollen preserved in growing speleothems provides important new opportunities to develop vegetation and climatic records that can be dated accurately with radiometric methods. However, when pollen is present in speleothems, concentrations can vary by orders of magnitude, highlighting how little we know about the processes that transport pollen into caves and onto speleothem surfaces, and that determine the pollen's preservation probability. To explore these aspects of speleothem pollen taphonomy, we investigated the distribution of pollen and microscopic charcoal within several stalagmites from southwest Australia. We examined spatial patterns in pollen and charcoal preservation in order to distinguish whether observed gradients result from preservation or are products of systematic transport processes working along stalagmite surfaces. We find that pollen grains and charcoal fragments are located preferentially on the flanks of most stalagmites. This suggests that pollen grain and charcoal deposition on speleothems is influenced by transport and accumulation of detrital debris on growing surfaces. These insights will assist in future sampling campaigns focusing on speleothem pollen and charcoal contents.

In this study, we assess charcoal records from eolian deposits within the Cooloola Sand Mass, a subtropical coastal dune system in eastern Australia, to determine whether they can be used as a proxy for Holocene fire history. We excavate four profiles in depositional wedges at the base of dune slipfaces (footslope deposits) and calculate charcoal concentrations for three size classes (180–250 μm, 250–355 μm, and 355 μm–2 mm) at predetermined depth intervals. Age–depth models are constructed for each profile using radiocarbon measurements (n = 46) and basal optically stimulated luminescence ages (n = 4). All records appear intact with little evidence of postdepositional mixing as demonstrated by minimal age reversals and consistent trends in charcoal concentration and accumulation rates (CHAR) among size classes. Combining all four records, we generate a ca. 7 cal ka BP terrestrial fire history that depicts distinct peaks representing periods of increased local fire activity at <0.3, 1.1–0.4, 2.2–1.6, 3.4–2.6, and 6.7–5.3 cal ka BP. Our findings parallel regional records and highlight the utility of dune footslopes as ecological and sedimentary archives. As dune fields are much more common than wetlands and lakes in semiarid and arid areas, these deposits have the potential to increase the spatial resolution of fire records globally.

Shipping radiocarbon samples from the scientist to the laboratories involves packaging and wrapping them with all sorts of bags and materials to make sure the samples arrive safely. Over the years a variety of possible and impossible package materials have arrived at our laboratory, causing problems occasionally but often being the highlight of the day cheering up the people involved. The reality of excavating important, occasionally unexpected, samples during field work sometimes includes taking samples when time is short or package materials could not be prepared. At this point, any kind of package becomes useful. Things like cigarette packets, reused office packets, tissue boxes, or medical packaging can become handy. But sometimes samples are taken, wrapped in aluminum foil, and forgotten in the desks. This article celebrates creativity, giving an overview of the many ways samples can be packed. However, using some of the less-than-ideal choices, drawbacks will be shown and possible problems explained.

Wetland sediments are valuable archives of environmental change but can be challenging to date. Terrestrial macrofossils are often sparse, resulting in radiocarbon (14C) dating of less desirable organic fractions. An alternative approach for capturing changes in atmospheric 14C is the use of terrestrial microfossils. We 14C date pollen microfossils from two Australian wetland sediment sequences and compare these to ages from other sediment fractions (n = 56). For the Holocene Lake Werri Berri record, pollen 14C ages are consistent with 14C ages on bulk sediment and humic acids (n = 14), whilst Stable Polycyclic Aromatic Carbon (SPAC) 14C ages (n = 4) are significantly younger. For Welsby Lagoon, pollen concentrate 14C ages (n = 21) provide a stratigraphically coherent sequence back to 50 ka BP. 14C ages from humic acid and >100 µm fractions (n = 13) are inconsistent, and often substantially younger than pollen ages. Our comparison of Bayesian age-depth models, developed in Oxcal, Bacon and Undatable, highlight the strengths and weaknesses of the different programs for straightforward and more complex chrono-stratigraphic records. All models display broad similarities but differences in modeled age-uncertainty, particularly when age constraints are sparse. Intensive dating of wetland sequences improves the identification of outliers and generation of robust age models, regardless of program used.

The most widely used dating techniques in quaternary research are the radiocarbon (14C) and optically stimulated luminescence (OSL) dating methods. In some environments, the investigated sediments do not contain enough material for 14C dating. In these cases, 14C dating of bulk sediment may be used as a last resort. The major aim of the present study was to determine the reliability and limitations of the different fractions of the soil organic carbon (SOC) 14C ages in the Nyírség blown-sand study area, in Hungary. Therefore, the low- and high-temperature combustions of SOC (LT-SOC and HT-SOC) 14C age of fossil soils were compared with the charcoal ages from the same fossil soil layer, and their (LT-SOC, HT-SOC, and charcoal) age reliability was verified independently by applying OSL to the quartz fraction of the sediment samples. The 14C data show variable agreement with OSL ages. Charcoal fragments were collected from some of the best material for 14C dating and their ages are in agreement with the LT and HT-SOC 14C ages and OSL data. The 14C age LT-SOC gives a reliable, credible ages, which were confirmed by independent OSL measurements. If buried soils do not contain any other macroscopic remnants for 14C dating, the LT-SOC 14C ages can be used, in the case of the Nyírség study area. The LT-SOC, which is the younger fraction of the soil organic carbon, may be considered to represent the burial time of the fossil soil layer. The HT-SOC 14C ages are sometimes unrealistically older than expected and cannot be considered to be reliable.

This study is on the absolute age dating of a multicultural site of Erenda, East Medinipur district, in coastal West Bengal, India. Charcoal samples were collected and measured using the accelerator mass spectrometry (AMS) facility at the Inter-University Accelerator Centre, New Delhi, India. These samples were collected from secured stratigraphic context of two excavated trenches. A careful collection of samples from two trenches provided us with the first calendar dates, 950 BCE and 1979 BCE, of protohistoric sites in coastal West Bengal. These calibrated calendar dates not only have wider significance in terms of archaeology but also methodological implications to understand the relevance of application of AMS from the dynamic coastal landscape in the humid tropics during the late Holocene period.

Changes in climate and fire regime have long been recognized as drivers of the postglacial vegetation history of Yellowstone National Park, but the effects of locally dramatic hydrothermal activity are poorly known. Multi-proxy records from Goose Lake have been used to describe the history of Lower Geyser Basin where modern hydrothermal activity is widespread. From 10,300 cal yr BP to 3800 cal yr BP, thermal waters discharged into the lake, as evidenced by the deposition of arsenic-rich sediment, fluorite mud, and relatively high δ13Csediment values. Partially thermal conditions affected the limnobiotic composition, but prevailing climate, fire regime, and rhyolitic substrate maintained Pinus contorta forest in the basin, as found throughout the region. At 3800 cal yr BP, thermal water discharge into Goose Lake ceased, as evidenced by a shift in sediment geochemistry and limnobiota. Pollen and charcoal data indicate concurrent grassland development with limited fuel biomass and less fire activity, despite late Holocene climate conditions that were conducive to expanded forest cover. The shift in hydrothermal activity at Goose Lake and establishment of the treeless geyser basin may have been the result of a tectonic event or change in hydroclimate. This record illustrates the complex interactions of geology and climate that govern the development of an active hydrothermal geo-ecosystem.

Analyses of macroscopic charcoal, sediment geochemistry (%C, %N, C/N, δ13C, δ15N), and fossil pollen were conducted on a sediment core recovered from Stella Lake, Nevada, establishing a 2000 year record of fire history and vegetation change for the Great Basin. Charcoal accumulation rates (CHAR) indicate that fire activity, which was minimal from the beginning of the first millennium to AD 750, increased slightly at the onset of the Medieval Climate Anomaly (MCA). Observed changes in catchment vegetation were driven by hydroclimate variability during the early MCA. Two notable increases in CHAR, which occurred during the Little Ice Age (LIA), were identified as major fire events within the catchment. Increased C/N, enriched δ15N, and depleted δ13C values correspond with these events, providing additional evidence for the occurrence of catchment-scale fire events during the late fifteenth and late sixteenth centuries. Shifts in the vegetation community composition and structure accompanied these fires, with Pinus and Picea decreasing in relative abundance and Poaceae increasing in relative abundance following the fire events. During the LIA, the vegetation change and lacustrine geochemical response was most directly influenced by the occurrence of catchment-scale fires, not regional hydroclimate.

An international consortium of radiocarbon (14C) laboratories was established to date the origin of the St. George’s Rotunda in Nitrianska Blatnica (Slovakia), because its age was not well established in previous investigations. Altogether, 20 samples of wood, charcoal, mortar and plaster were analyzed. The 14C results obtained from the different laboratories as well as between the different sample types were in good agreement, resulting in a 14C calibrated age of 783–880 AD (94.2% probability) for the Rotunda. Although the 14C results have very good precision, the specific plateau-shape of the calibration curve in this period caused the wide range of the calibrated age. The probability distribution from OxCal calibration shows, however, that about 86% of the probability distribution lies in the period before 863 AD, implying that the Rotunda could have been constructed before the arrival of Constantine (St. Cyril) and St. Methodius to Great Moravia. The Rotunda thus probably represents the oldest standing purpose-built Christian church in the eastern part of Central Europe.

This paper integrates the first rock art directly dated with radiocarbon (14C) in Southeast Asia with the archaeological activity in the area and with stylistically similar rock art in the region. Peñablanca is a hotspot of archaeological research that includes the oldest dates for human remains in the Philippines. The caves in Peñablanca with known rock art were revisited and only 37.6% of the original recorded figures were found; the others are likely lost to agents of deterioration. A sample was collected from an anthropomorph and accelerator mass spectrometry (AMS) dated to 3570–3460 cal BP. The date corresponds to archaeological activity in the area and provides a more holistic view of the people inhabiting the Peñablanca caves at that time. A systematic review was used to find similar black anthropomorph motifs in Southeast Asia to identify potential connections across the region and provide a possible chronological association.

Agricultural production on the Mahafaly Plateau in SW-Madagascar has traditionally been based on subsistence rain-fed agriculture, with yields declining as a result of low soil fertility, recurrent droughts, and erratic rainfall. Market-oriented vegetable production in this area may help households improve their nutrition and diversify their income. In field trials between the 2013 and 2016 dry cropping seasons, the feasibility of carrot (Daucus carota L.) and onion (Allium cepa L.) production was assessed by testing effects of manure and charcoal amendments, shading, and seed quality on yields. Due to damage caused by cyclones and strong winds, only data from 2013 and 2016 are reported in this paper. Additionally to the field experiments, effects of salinity on seed germination were also examined under laboratory conditions and in the field. Carrot dry matter (DM) yields were 0.24 to 2.76 t·ha−1 while those of onion were 0.15 to 0.99 t·ha−1 DM. While the combination of manure and charcoal application had only minor effects on crop growth, manure alone increased carrot yield by 26% across years. After one cropping season, manure application reduced soil pH from 9.0 to 8.6 and increased soil Corg from 0.87 to 1.76%, N from 0.08 to 0.14%, and P from 10.6 to 15.1 mg·kg−1. Shading reduced carrot yields from 0.87 to 0.58 t·ha−1 DM in 2013 and from 1.87 to 0.85 t·ha−1 DM in 2016, but increased onion yield in 2013 from 0.24 to 0.62 t·ha−1 DM. Carrot seed procured locally performed better in the field than seed imported from the capital which translated into differences in seedling emergence. Saline irrigation water (electrical conductivity = 7.03 mS·cm−1) reduced seedling emergence rate of carrot from 73 to 20% and for onion from 44 to 28% and unprimed seeds performed better than primed ones. Using shading during the dry season is not advisable for carrot and onion production, but improving seed quality and targeted use of soil amendments (time of manure application, manure quality) may enhance vegetable yields.

Sedimentary charcoal records are used for understanding fire as an earth system process; however, no standardized laboratory methodology exists. Varying sample volumes and chemical treatments (i.e., type of chemical for length of time) are used for the deflocculation and extraction of charcoal from sediment samples. Here, we present the first systematic assessment of the effect of commonly used chemicals on charcoal area and number of fragments. In modern charcoal the area of fragments was significantly different depending on the chemical treatment. We subsequently applied H2O2 (33%), NaClO (12.5%), and HNO3 (50%) to a late-glacial–early Holocene paleorecord and tested different sample volumes. The effects of the treatments were consistent between modern and fossil experiments, which demonstrates the validity of applying results from the modern experiment to the fossil records. Based on our experiments we suggest (1) H2O2 33%, especially for highly organic sediments; (2) avoidance of high concentrations of NaClO for prolonged periods of time, and of HNO3; and (3) samples of 1 cm3 provided typically consistent profiles. Our results indicate that charcoal properties can be influenced by treatment type and sample volume, thus emphasizing the need for a common protocol to enable reliable multi-study comparisons or composite fire histories.