Lightweight, high-strength, reinforced plastic tube-franging die

Dies of a phenolic molding compound with chopped glass fibers as fill material possess a flexural strength of 20,000 psi and a compressive strength of 28,500 psi

A chironomid-based reconstruction of summer temperatures in NW Iceland since AD 1650

Few studies currently exist that aim to validate a proxy chironomid-temperature reconstruction with instrumental temperature measurements. We used a reconstruction from a chironomid percentage abundance data set to produce quantitative summer temperature estimates since AD 1650 for NW Iceland through a transfer function approach, and validated the record against instrumental temperature measurements from Stykkishólmur in western Iceland. The core was dated through Pb-210, Cs-137 and tephra analyses (Hekla 1693) which produced a well-constrained dating model across the whole study period. Little catchment disturbance, as shown through geochemical (Itrax) and loss-on-ignition data, throughout the period further reinforce the premise that the chironomids were responding to temperature and not other catchment or within-lake variables. Particularly cold phases were identified between AD 1683–1710, AD 1765–1780 and AD 1890–1917, with relative drops in summer temperatures in the order of 1.5–2°C. The timing of these cold phases agree well with other evidence of cooler temperatures, notably increased extent of Little Ice Age (LIA) glaciers. Our evidence suggests that the magnitude of summer temperature cooling (1.5–2°C) was enough to force LIA Icelandic glaciers into their maximum Holocene extent, which is in accordance with previous modelling experiments for an Icelandic ice cap (Langjökull)

Was there a '4.2ka event' in Great Britain and Ireland? Evidence from the peatland record

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Palaeoenvironmental and archaeological data from several regions around the world show evidence of a multi-centennial climatic event occurring approximately 4200cal yr BP (4.2ka). Whilst the climatic change and/or impact of the 4.2ka event is clear in certain regions, such as western Asia, evidence for the event has yet to be fully evaluated in northwest Europe. This study presents high-resolution, multi-proxy palaeoclimate records from sites in Northern Ireland, ideally located for an objective examination of the nature of the event in Great Britain and Ireland within the broader context of mid-Holocene climate change c. 6.5-2.5ka. The peatlands of northwest Europe possess considerable potential for the examination of climatic change in the North Atlantic region, demonstrated by the range of palaeohydrological proxy data generated during this study (peat humification, plant macrofossil and testate amoebae analyses) supported by a high-resolution chronology (including comprehensive AMS 14 C and tephrochronology). The inter-site testate amoebae reconstructions appear coherent and were combined to produce a regional climatic record, in marked contrast to the plant macrofossil and peat humification records that appear climatically complacent. The testate amoebae reconstruction, however, provides no compelling evidence for a 4.2ka event signal and is consistent with previously reported studies from across northwest Europe, suggesting the origin and impact of this event is spatially complex. © 2013 Elsevier Ltd.This research was carried out while T.P.R. held a UK Natural Environment Research Council studentship (NE/G524328/1) at the University of Exeter.

The 5.2 ka climate event: Evidence from stable isotope and multi-proxy palaeoecological peatland records in Ireland

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Evidence for a major climate event at 5.2 ka has been reported globally and is associated with considerable societal disruption, but is poorly characterised in northwest Europe. This event forms part of a broader period of re-organisation in the Earth's ocean-atmosphere circulation system between 6 and 5 ka. This study tests the nature and timing of the event in northwest Europe, a region highly sensitive to change in meridional overturning circulation and mid-latitude westerly airflow. Here we report three high-resolution Irish multi-proxy records obtained from ombrotrophic peatlands that have robust chronological frameworks. We identify the 5.2 ka event by a sustained decrease in δ 18 O cellulose at all three sites, with additional and parallel changes in δ 13 C cellulose and palaeoecological (testate amoebae, plant macrofossil and humification) data from two sites in northern Ireland. Data from Sluggan Moss demonstrate a particularly coherent shift towards wetter conditions. These data support the hypothesis that the event was caused by a prolonged period of positive North Atlantic Oscillation conditions, resulting in pervasive cyclonic weather patterns across northwest Europe, increasing precipitation over Ireland.This research was carried out while T.P.R. held UK Natural Environment Research Council studentship at the University of Exeter (NE/G524328/1) and T.J.D held a studentship at the University of Southampton tied to the NERC RAPID Programme (NER/T/S/2002/00460). Radiocarbon support was provided by the NERC 14C Steering Committee (Allocation No.: 1523.0910), the NERC RAPID Programme and the Irish Quaternary Association via the IQUA Bill Watts 14Chrono award

The 5.2 ka climate event: Evidence from stable isotope and multi-proxy palaeoecological peatland records in Ireland

AbstractEvidence for a major climate event at 5.2 ka has been reported globally and is associated with considerable societal disruption, but is poorly characterised in northwest Europe. This event forms part of a broader period of re-organisation in the Earth's ocean-atmosphere circulation system between 6 and 5 ka. This study tests the nature and timing of the event in northwest Europe, a region highly sensitive to change in meridional overturning circulation and mid-latitude westerly airflow. Here we report three high-resolution Irish multi-proxy records obtained from ombrotrophic peatlands that have robust chronological frameworks. We identify the 5.2 ka event by a sustained decrease in δ18Ocellulose at all three sites, with additional and parallel changes in δ13Ccellulose and palaeoecological (testate amoebae, plant macrofossil and humification) data from two sites in northern Ireland. Data from Sluggan Moss demonstrate a particularly coherent shift towards wetter conditions. These data support the hypothesis that the event was caused by a prolonged period of positive North Atlantic Oscillation conditions, resulting in pervasive cyclonic weather patterns across northwest Europe, increasing precipitation over Ireland

Spatial Analysis of Cirques from Three Regions of Iceland: Implications for Cirque Formation and Palaeoclimate

This study is a quantitative analysis of cirques in three regions of Iceland: Tröllaskagi, the East Fjords and Vestfirðir. Using Google Earth and the National Land Survey of Iceland Map Viewer, we identified 347 new cirques on Tröllaskagi and the East Fjords region, and combined these data with 100 cirques previously identified on Vestfirðir. We used ArcGIS to measure length, width, aspect, latitude and distance to coastline of each cirque. Palaeo‐equilibrium‐line altitudes (palaeo‐ELAs) of palaeo‐cirque glaciers were calculated using the altitude‐ratio method, cirque‐floor method and minimum‐point method. The mean palaeo‐ELA values in Tröllaskagi, the East Fjords and Vestfirðir are 788, 643 and 408 m a.s.l, respectively. Interpolation maps of palaeo‐ELAs demonstrate a positive relationship between palaeo‐ELA and distance to coastline. A positive relationship between palaeo‐ELA and latitude is observed on Vestfirðir, a negative relationship is observed on Tröllaskagi and no statistically significant relationship is present on the East Fjords. The modal orientation of cirques on Tröllaskagi and Vestfirðir is northeast, while orientation of cirques in the East Fjords is north. Palaeo‐wind reconstructions for the LGM show that modal aspect is aligned with the prevailing north‐northeast wind directions, although aspect measurements demonstrate wide dispersion. Cirque length is similar on Tröllaskagi and the East Fjords, but cirques are approximately 200 m shorter in Vestfirðir. Cirque widths are similar in all three regions. Comparisons with a global data set show that cirques in Iceland are smaller and more circular than cirques in other regions of the world. Similar to glaciers in Norway and Kamchatka, our results demonstrate that access to a moisture source is a key parameter in determining palaeo‐ELAs in Iceland. Temperatures interpreted from palaeo‐ELA depressions suggest that these cirques may have been glaciated as recently as the Little Ice Age

Iron Age Promontory Fort to Medieval Castle? Excavations at Great Castle Head, Dale, Pembrokeshire 1999

Great Castle Head Iron Age promontory fort has some of the most massive defences of all the coastal forts of Pembrokeshire. However, due to coastal erosion, it has one of the smallest surviving internal areas and the remains are bisected by a former landslip. The threat posed by continuing erosion prompted a survey and rescue excavation in the summer of 1999. The site is characterised by two lines of defences each consisting of a bank, a ditch and a counterscarp bank. It is suggested that the original entrance was adjacent to the cliff edge to the north of the surviving defences and that the present entrance through the outer defences probably dates to the earlier 20th century. The results of the excavation indicated that the inner bank had at least three phases of construction, with the earliest phase possibly dating to the Early or Middle Iron Age. It seems probable that the more massive, second phase of the defences dates to the late Iron Age although a later date cannot be ruled out. Evidence from the interior of the fort indicated intensive occupation during the later prehistoric period. However, no clear structures could be identified due to the fragmentary nature of the results from the small area that was excavated. The third phase of inner bank construction suggests that the site was re-fortified during the late 12th and 13th centuries A.D. Further evidence for mediaeval activity is provided by a spread of pottery within the interior of the fort. It is argued that there is a strong case to suggest that, during this period, Great Castle Head became the site of a small mediaeval castle

The importance of sub-peat carbon storage as shown by data from Dartmoor, UK

Peatlands are highly valued for their range of ecosystem services, including distinctive biodiversity, agricultural uses, recreational amenities, water provision, river flow regulation and their capacity to store carbon. There have been a range of estimates of carbon stored in peatlands in the United Kingdom, but uncertainties remain, in particular with regard to depth and bulk density of peat. In addition, very few studies consider the full profile with depth in carbon auditing. The importance of sub-peat soils within peatland carbon stores has been recognized, but remains poorly understood and is included rarely within peatland carbon audits. This study examines the importance of the carbon store based on a study of blanket peat on Dartmoor, UK, by estimating peat depths in a 4 × 1 km survey area using ground penetrating radar (GPR), extraction of 43 cores across a range of peat depth, and estimation of carbon densities based on measures of loss-on-ignition and bulk density. Comparison of GPR estimates of peat depth with core depths shows excellent agreement, to provide the basis for a detailed understanding of the distribution of peat depths within the survey area. Carbon densities of the sub-peat soils are on average 78 and 53 kg C/m3 for the overlying blanket peat. There is considerable spatial variability in the estimates of total carbon from each core across the survey area, with values ranging between 56.5 kg C/m2 (1.01 m total depth of peat and soil) and 524 kg C/m2 (6.63 m total depth). Sub-peat soil carbon represents between 4 and 28 per cent (mean 13.5) of the total carbon stored, with greater values for shallower peat. The results indicate a significant and previously unaccounted store of carbon within blanket peat regions which should be included in future calculations of overall carbon storage. It is argued that this store needs to be considered in carbon audits. © 2013 British Society of Soil Science