Browsing by Author "Brock, Fiona"
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Item Open Access The ballistic performance of bone when impacted by fragments(Springer, 2020-05-02) Caister, A. J.; Carr, Debra J.; Campbell, P. D.; Brock, Fiona; Breeze, JohnPhysical models are required to generate the underlying algorithms that populate computer simulations of the effects of explosive fragmenting devices. These models and simulations are used for understanding weapon performance, designing buildings and optimising personal protective equipment. Previous experimental work has investigated the performance of skin and muscle when subjected to fragmentation threats, but limited evidence exists for the performance of bone when impacted by fragments. In the current work, ballistic testing was conducted using two types of internationally recognised steel fragment simulating projectiles (FSPs): (i) 5.5 mm diameter (0.68 g) ball bearing (BBs) and (ii) 1.10 g chisel nosed (CN). These projectiles were fired at isolated swine ribs at impact velocities between 99 and 1265 m/s. Impact events were recorded using a high-speed camera. Selected specimens were analysed post-impact with plain x-radiographs and micro-CT scanning to determine damage to the bone architecture. Bones were perforated with a kinetic energy density (KED) as low as 0.14 J/mm2. Energy transfer to the bone was greater for the CN FSPs, resulting in increased bone damage and the production of secondary bone fragments. The manner in which the bones failed with faster velocity impacts (> 551 m/s; KED > 6.44 J/mm2) was analogous to the behaviour of a brittle material. Slower velocity impacts (< 323 m/s; KED < 1.49 J/mm2) showed a transition in failure mode with the bone displaying the properties of an elastic, plastic and brittle material at various points during the impact. The study gives critical insight into how bone behaves under these circumstances.Item Open Access Black pitch, carved histories: radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's Pitch Lake(Elsevier, 2017-11-06) Ostapkowicz, J.; Brock, Fiona; Widenhoeft, A. C.; Snoeck, C.; Pouncett, J.; Baksh-Comeau, Y.; Schulting, Rick J.; Claeys, P.; Mattielli, N.; Richards, M.; Boomert, A.We report on the results of a multi-disciplinary project (including wood identification, radiocarbon dating and strontium isotope analysis) focused on a collection of pre-Columbian wooden carvings and human remains from Pitch Lake, Trinidad. While the lake's unusual conditions are conducive to the survival of organic artefacts, they also present particular challenges for analysis. There is a loss of any contextual association beyond that of the lake, and specific methodologies are required to deal with pitch contamination. A surprising taxonomic range of woods was employed for the various utilitarian and ceremonial items recovered. The 14C results range from ca. 3200 BCE to ca. 700 CE, and include the earliest known wooden carvings in the entire Caribbean. The strontium isotope results - interpreted with the aid of an isoscape developed for the project, based on extensive samples of modern trees across Trinidad and Tobago - indicate that most carvings are consistent with the site's immediate environs; however, a ‘weaving tool’ came from a more radiogenic region that is unlikely to be found on Trinidad, suggesting links with the South American mainland.Item Open Access Bomb-pulse radiocarbon dating of modern paintings on canvas(Cambridge University Press, 2019-07-11) Brock, Fiona; Eastaugh, Nicholas; Ford, Thierry; Townsend, Joyce H.Radiocarbon (14C) dating has previously been applied to modern paintings on canvas from the 20th century to identify potential modern forgeries, and dates indicate a time lag of several years between the harvesting of plant fibers for making canvas, and completion of a painting. This study investigated both the length of this time lag and the potential of 14C dating to inform about an individual artist’s mode of working (for example long-term storage or reuse of canvases, or extended reworking on a single canvas) and/or to establish a chronology for a corpus of work. Two pre-bomb and 16 post-bomb artworks by 17 mid-20th-century Scandinavian artists were 14C dated. The majority of post-bomb samples indicated a time lag of 2–5 years between the harvesting of the plants and completion of a painting, but some samples recorded lags of up to 10 years, and others produced much earlier results, potentially indicating the use of much older canvases or challenges removing contamination prior to dating. The importance of thorough pre-screening of canvas samples for both synthetic fibers and contaminants prior to dating, and selection of the most suitable calibration curve, are highlighted.Item Open Access Chemical characteristics of macroscopic pyrogenic carbon following millennial-scale environmental exposure(Frontiers, 2020-01-21) Ascough, Philippa L.; Brock, Fiona; Collinson, Margaret E.; Painter, Jonathan; Lane, David W.; Bird, Michael I.Pyrogenic Carbon (PyC) is ubiquitous in global environments, and is now known to form a significant, and dynamic component of the global carbon cycle, with at least some forms of PyC persisting in their depositional environment for many millennia. Despite this, the factors that determine the turnover of PyC remain poorly understood, as do the physical and chemical changes that this material undergoes when exposed to the environment over tens of thousands of years. Here, we present the results of an investigation to address these knowledge gaps through chemical and physical analysis of a suite of wood PyC samples exposed to the environment for varying time periods, to a maximum of >90,000 years. This includes an assessment of the quantity of resistant carbon, known as Stable Polyaromatic Carbon (SPAC) versus more chemically labile carbon in the samples. We find that, although production temperature is likely to determine the initial ‘degradation potential’ of PyC, an extended exposure to environmental conditions does not necessarily mean that remaining PyC always progresses to a ‘SPAC-dominant’ state. Instead, some ancient PyC can be composed largely of chemical components typically thought of as environmentally labile, and it is likely that the depositional environment drives the trajectory of preservation versus loss of PyC over time. This has important implications for the size of global PyC stocks, which may have been underestimated, and also for the potential loss of previously stored PyC, when its depositional environment alters through environmental or climatic changes.Item Open Access Dark materials: pre-Columbian black lithic carvings from St Vincent and the wider Caribbean(Elsevier, 2020-06-07) Brock, Fiona; Ostapkowicz, Joanna; Collinson, Margaret Elizabeth; Bull, Ian D.; Dyer, Chris; Lane, David W.; Domoney, Kelly; Uden, JeremyA small number of pre-Columbian black lithic carvings have been found at archaeological sites across the Caribbean, as well as in parts of neighbouring mainland South America. The identity of the material used to create these artefacts is often unknown, but suggestions include lignite, wood, petrified wood, manja(c)k, jet (or ‘jet-like’ materials) and hardened asphalt. These identifications are often historical and lacking any scientific basis, and as such can be unreliable. However, identification of the material has the potential to inform on the source of the carving and thereby pre-Columbian trade routes within the circum-Caribbean region. Four analytical techniques (reflectance microscopy, FTIR, Py-GC/MS, x-ray fluorescence) were applied to samples taken from two carvings found on St Vincent and five comparative materials. Both artefacts were found to be most likely carved from cannel coal, indicating that they originated in South America (where cannel coal is found extensively in locations in Colombia and Venezuela), as the material is not found within the Caribbean region.Item Open Access Dating Thach Lac: cryptic CaCO3 diagenesis in archaeological food shells and implications for 14c(Cambridge University Press, 2022-09-09) Petchey, Fiona; Piper, Phillip J.; Dabell, Kathleen; Brock, Fiona; Turner, Helen; Dzung, Lam Thi MyIn many locations around the world, shell radiocarbon dates underpin archaeological research. The dating of shell brings the chronological relationship between the sample and target event (e.g., hunting and food preparation) into congruence, while shells are valuable geochemical proxies for understanding past climate dynamics and environments. However, this information can be lost as the shell, composites of biopolymers and carbonate minerals (mostly calcite and or aragonite), undergo diagenetic alteration. While studies into Pleistocene-age carbonates are common in the radiocarbon literature, there has been little research into the impact of alteration on Holocene-age shells used to interpret recent societal developments. The limits of our understanding of these diagenetic changes became evident when dating Placuna placenta (naturally calcitic) and Tegillarca granosa (naturally aragonitic) shells from the site of Thach Lac in Vietnam. These shells returned ages significantly younger than associated charcoal and terrestrial bone at the site, but standard tests for secondary recrystallization (XRD and staining techniques) did not indicate any alteration. Further investigation revealed that cryptic recrystallization (i.e., of the same crystal structure) had occurred in both the calcite and aragonite shells. This finding suggests recrystallization may have an undetected impact on some shell radiocarbon dates.Item Open Access The earliest directly dated rock paintings from southern Africa: new AMS radiocarbon dates(Cambridge Univ Press, 2017-04-04) Bonneau, Adelphine; Pearce, David; Mitchell, Peter; Staff, Richard; Arthur, Charles; Mallen, Lara; Brock, Fiona; Higham, TomRock art worldwide has proved extremely difficult to date directly. Here, the first radiocarbon dates for rock paintings in Botswana and Lesotho are presented, along with additional dates for Later Stone Age rock art in South Africa. The samples selected for dating were identified as carbon-blacks from short-lived organic materials, meaning that the sampled pigments and the paintings that they were used to produce must be of similar age. The results reveal that southern African hunter-gatherers were creating paintings on rockshelter walls as long ago as 5723–4420 cal BP in south-eastern Botswana: the oldest such evidence yet found in southern Africa.Item Open Access East-central Florida pre-Columbian wood sculpture: Radiocarbon dating, wood identification and strontium isotope studies(Elsevier, 2017-05-13) Ostapkowicz, J.; Schulting, Rick J.; Wheeler, R.; Newsome, L.; Brock, Fiona; Bull, I.; Snoeck, C.Item Open Access Etton Causewayed Enclosure Bone Diagenesis data(Cranfield University, 2023-01-03 15:42) Brock, Fiona; Loy, Charlotte; Dyer, ChrisXRF and FTIR data collected by Charlotte Loy as part of her Forensic Archaeology & Anthropology MSc thesis entitled 'Investigating the Peculiar Diagenesis of the Etton Causewayed Enclosure Bones' (2016). These Neolithic animal bones show unusual patterns of iron and manganese mineralisation.Item Open Access Forensic radiocarbon dating of human remains: the past, the present, and the future(Equinox Publishing, 2017-07-01) Brock, Fiona; Cook, G. T.Radiocarbon dating is a valuable tool for the forensic examination of human remains in answering questions as to whether the remains are of forensic or medico-legal interest or archaeological in date. The technique is also potentially capable of providing the year of birth and/or death of an individual. Atmospheric radiocarbon levels are currently enhanced relative to the natural level due to the release of large quantities of radiocarbon (14C) during the atmospheric nuclear weapons testing of the 1950s and 1960s. This spike, or “bomb-pulse,” can, in some instances, provide precision dates to within 1–2 calendar years. However, atmospheric 14C activity has been declining since the end of atmospheric weapons testing in 1963 and is likely to drop below the natural level by the mid-twenty-first century, with implications for the application of radiocarbon dating to forensic specimens.Item Open Access Identification of a new hominin bone from Denisova Cave, Siberia using collagen fingerprinting and mitochondrial DNA analysis(Springer Nature, 2016-03-29) Brown, Samantha; Higham, Thomas; Slon, Viviane; Pääbo, Svante; Meyer, Matthias; Douka, Katerina; Brock, Fiona; Comeskey, Daniel; Procopio, Noemi; Shunkov, Michael; Derevianko, Anatoly; Buckley, MichaelDNA sequencing has revolutionised our understanding of archaic humans during the Middle and Upper Palaeolithic. Unfortunately, while many Palaeolithic sites contain large numbers of bones, the majority of these lack the diagnostic features necessary for traditional morphological identification. As a result the recovery of Pleistocene-age human remains is extremely rare. To circumvent this problem we have applied a method of collagen fingerprinting to more than 2000 fragmented bones from the site of Denisova Cave, Russia, in order to facilitate the discovery of human remains. As a result of our analysis a single hominin bone (Denisova 11) was identified, supported through in-depth peptide sequencing analysis, and found to carry mitochondrial DNA of the Neandertal type. Subsequent radiocarbon dating revealed the bone to be >50,000 years old. Here we demonstrate the huge potential collagen fingerprinting has for identifying hominin remains in highly fragmentary archaeological assemblages, improving the resources available for wider studies into human evolution.Item Open Access The importance of considering both depth of penetration and crater volume in forwards-ballistic penetrative experiments(AIP, 2023-09-26) Powell, Dan; Appleby-Thomas, Gareth J.; Painter, Jonathan; Brock, Fiona; Thirulogasingam, Thiru; Sagoo, Kam; Brown, Nick; Livesey, ChrisThe most common method of analysing armour performance is the Depth of Penetration (DoP). However, this one-dimensional measurement does not provide insight into the method of penetration or energy absorbed by the target; the crater could be particularly narrow or very wide and yield the same DoP. Analysis of the crater through Crater Volume (CV) provides a more detailed metric to be used alongside DoP to visualise the crater, indicating whether energy was dispersed over a large area. CV provides a wider insight into how a material resisted penetration events, giving evidence of potential defeat mechanisms. Digital reconstruction of the craters using X-ray radiographs or Computed Tomography (CT) scanning can also provide a useful tool for computational models to be compared against. The simple calculation of CV through X-ray radiography and image processing has been demonstrated to be accurate to within ±6% of the CT scanned CV. Success in utilising this analytical tool was demonstrated through comparison of three armour configurations. A consistent difference in the ratio of DoP:CV was seen between steel targets, ceramic-steel targets and ceramic-air-steel targets, indicating variation in the defeat mechanism between the three target configurations.Item Open Access Improving chronological control for environmental sequences from the last glacial period(Elsevier, 2017-10-14) Briant, R. M.; Brock, Fiona; Demarchi, B.; Langford, H. E.; Penkman, K. E. H.; Schreve, D. C.; Schwenninger, J. L.; Taylor, S.Recognition of palaeoclimatic instability in the Greenland ice cores has spurred researchers to identify corresponding evidence in other terrestrial records from the last glacial stage. Such evidence is critical for establishing how much environmental stress precipitated Neanderthal and Late Pleistocene megafaunal extinctions, although a need for improved chronology has been consistently highlighted. In formerly glaciated and periglaciated areas of northern Europe, palaeoenvironmental sequences are frequently discontinuous. These often yield high-resolution proxy-based quantitative palaeotemperature estimates but can be hard to date, due to difficulties in removing contamination from biological samples at the limits of the radiocarbon technique (c.30-50kya). Here we demonstrate, for the first time using samples with independent age control, that different radiocarbon pretreatments can generate different age data and that gentler, less effective treatments applied to avoid sample loss may not yield reliable age-estimates. We advocate alternative harsher pretreatment using a strong acid-base-acid protocol. This provides an acceptable balance between contamination removal and excessive sample loss and generates more accurate ages, significantly enhancing our ability to detect and understand the impacts of palaeoclimatic instability in the terrestrial record of the last glacial.Item Open Access Integrating the Old World into the New: an ‘Idol from the West Indies’(Cambridge University Press, 2017-09-20) Ostapkowicz, Joanna; Brock, Fiona; Widenhoeft, Alex C.; Schulting, Rick J.; Daviola, DonatellaThe Pigorini cemí is an icon of Caribbean colonial history, reflecting early trans-Atlantic cross-cultural exchanges. Although well documented, the piece has received surprisingly little systematic study. We present the first structural analysis and radiocarbon dating of the sculpture (modelled at AD 1492–1524), and a brief discussion of the materials from which it is comprised. These include indigenous shell and European glass beads, newly identified feather and hair fibres, and the enigmatic rhinoceros-horn mask carved as a human face. We also address the sculpture's hidden internal wooden base, which is shown to be a non-indigenous display mount made of European willow (Salix sp.).Item Open Access Interpreting the chronology of the cist(Oxbow Books, 2016-09-30) Marshall, Peter; Bronk Ramsay, Christopher; Russell, Nicola; Brock, Fiona; Reimer, PaulaThe wide range of organic material preserved in the cist provided the opportunity for determining a robust chronology for the cremation and its associated grave goods. In addition, the peat mound into which the cist had been placed had the potential to provide an environmental setting and context for the burial.Item Open Access Investigating diagenesis of archaeological bones from Etton Causewayed Enclosure, UK(Elsevier, 2023-01-02) Loy, Charlotte; Brock, Fiona; Dyer, ChrisDiagenesis of archaeological bones proceeds via a complex combination of chemical, physical and/or microbial processes often over several millennia. These processes are influenced by the depositional environment, including fluctuations in pH, mineral availability and water table. This study investigates diagenetic alterations to the mineral and organic (collagen) phases of bones from a Neolithic site, Etton Causewayed Enclosure (Cambridgeshire, UK). Archaeological bones from some layers of the gravel site at Etton exhibit unusual staining patterns, including iron and manganese rich layers underneath the exterior bone surface and manganese speckling throughout the bone. A range of analytical techniques (micro-CT, FTIR, XRF and SEM-EDS) were employed to investigate the mineralisation within three bones from this site. Diagenesis appears to have occurred through a combination of bacterial degradation and mineral formation due to the changing redox conditions at the site caused by fluctuating groundwater. The reason for the positioning of the manganese layers beneath the iron layers at the surfaces of the bone remains unclear.Item Open Access Isotopic evidence for long-distance connections of the AD thirteenth century Promontory caves occupants(Cambridge University Press, 2021-03-02) Metcalfe, Jessica Z.; Ives, John W.; Shirazi, Sabrina; Gilmore, Kevin P.; Hallson, Jennifer; Brock, Fiona; Clark, Bonnie J.; Shapiro, BethThe Promontory caves (Utah) and Franktown Cave (Colorado) contain high-fidelity records of short-term occupations by groups with material culture connections to the Subarctic/Northern Plains. This research uses Promontory and Franktown bison dung, hair, hide, and bone collagen to establish local baseline carbon isotopic variability and identify leather from a distant source. The ankle wrap of one Promontory Cave 1 moccasin had a δ13C value that indicates a substantial C4 component to the animal's diet, unlike the C3 diets inferred from 171 other Promontory and northern Utah bison samples. We draw on a unique combination of multitissue isotopic analysis, carbon isoscapes, ancient DNA (species and sex identification), tissue turnover rates, archaeological contexts, and bison ecology to show that the high δ13C value was not likely a result of local plant consumption, bison mobility, or trade. Instead, the bison hide was likely acquired via long-distance travel to/from an area of abundant C4 grasses far to the south or east. Expansive landscape knowledge gained through long-distance associations would have allowed Promontory caves inhabitants to make well-informed decisions about directions and routes of movement for a territorial shift, which seems to have occurred in the late thirteenth century.Item Open Access LA-ICP-MS analysis of late bronze age blue glass beads from Gurob, Egypt(Wiley, 2019-10-25) Kemp, Victoria; McDonald, A.; Brock, Fiona; Shortland, Andrew J.LA-ICP-MS analysis was undertaken on 37 blue glass beads excavated from a tomb in Gurob, in the Southern Fayum region of Egypt. The tomb was undisturbed, contained the remains of seven females and two children, and dated between the reigns of Amenhotep I (1525-1504 BC) and Tuthmosis III (1479-1425 BC). The glass beads are coloured by copper and the trace element concentrations are compositionally consistent with glasses from Mesopotamia, rather than from Egypt. Therefore, these glass beads represent a rare example of Mesopotamian glass to be discovered in Egypt, in addition to being some of the earliest glass found. Gurob is known to have been the site of a ‘harem palace’ established in the reign of Tuthmosis III (1479-1425 BC), the implication being that these beads represent luxury items transported into Egypt by high-ranking foreign women, possibly in connection with the harem palace.Item Open Access Laboratory intercomparison of Pleistocene bone radiocarbon dating protocols(University of Arizona - Cambridge University Press, 2017-06-21) Huels, M; van der Plicht, J; Brock, Fiona; Matzerath, S; Chivall, DSince its invention in the late 1940’s, radiocarbon dating has become an important tool for absolute dating. A prerequisite for the acceptance of this method is consistency between, and compatibility of, radiocarbon dates from different laboratories. To meet these requirements, international laboratory intercomparison studies with different sample materials are frequently performed (e.g. TIRI, FIRI, VIRI and, most recently, SIRI). Intercomparison is especially relevant and difficult for samples close to the dating limit of ~50 kBP, not least for bone samples. A radiocarbon intercomparison study between the Leibniz-Laboratory in Kiel (Germany), the Centre for Isotope Research (CIO) in Groningen (The Netherlands), and the Oxford Radiocarbon Accelerator Unit (ORAU; United Kingdom) was performed on three Pleistocene (MIS3) mammal bone samples from the Brick Quarry site Coenen (BQC) in Germany. The comparison of individually prepared and measured bone collagen radiocarbon activities, results from shared collagen measurements, and respective background signatures and correction points to the latter as the main factor responsible for observed differences in final given radiocarbon estimates.Item Open Access Modernist enamels: composition, microstructure and stability(Elsevier, 2019-11-13) Beltrán, Martí; Schibille, Nadine; Brock, Fiona; Gratuze, Bernard; Vallcorba, Oriol; Pradell, TrinitatColoured enamels from the materials used in Modernist workshops from Barcelona were produced and compared to those found in the buildings to explore the reason for the reduced stability of the blue and green enamels. They were made of a lead-zinc borosilicate glass with a low softening point, reasonable stability to corrosion and matching thermal expansion coefficient with the blown base glass, mixed with colourants and pigment particles. The historical enamels show a lead, boron and zinc depleted silica rich amorphous glass, with precipitated lead and calcium sulphates or carbonates, characteristic of extensive atmospheric corrosion. The blue and green enamels show a heterogeneous layered microstructure more prone to degradation which is augmented by a greater heating and thermal stress affectation produced by the enhanced Infrared absorbance of blue tetrahedral cobalt colour centres and copper ions dissolved in the glass and, in particular, of the cobalt spinel particles.