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"Anglesey"
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Landscape scale impacts of culling upon a European grey squirrel population: can trapping reduce population size and decrease the threat of squirrelpox virus infection for the native red squirrel?
by
Rushton, Steven P
,
McInnes, Colin J
,
Everest, David. J
in
Animal diseases
,
Animal, plant and microbial ecology
,
Applied ecology
2014
The control of grey squirrels (Sciurus carolinensis) is widely undertaken as a conservation measure to protect red squirrel (Sciurus vulgaris) populations in the UK. However, inconsistencies and omissions in data collection, as well as fluctuating financial resourcing of control efforts, have meant that it has to date proved difficult to quantify the impact of any regional control initiative upon populations. Here we have scrutinized a 13 years period (1998–2010) within an ongoing grey squirrel control project that reflects the resource challenges typically faced by red squirrel conservation programmes. We present evidence that despite variation in grey squirrel control intensity, the abundance of grey squirrels ultimately decreased significantly. Trapping success was significantly higher in spring and summer months and a greater abundance of grey squirrels was found in deciduous woodland and hazel dominated scrub relative to other habitats; two findings that reinforce existing guidance within national control best practice. Grey squirrels carry an infection that causes epidemic pathogenic disease if spread to the native red squirrel. We observed that the proportion of seropositive grey squirrels decreased constantly from 2003 to 2010 when only 4 % of sampled animals were seropositive. This discovery indicates that culling can in parallel remove both the competitive and disease threat posed to red by grey squirrels. The historical paucity of scientific data on the effectiveness of grey squirrel control as a tactic in UK red squirrel conservation means that the findings of this study will significantly advance conservation best practice and inform the development of future national strategy.
Journal Article
The structural interpretation of domainal trace lineation; an example from the Mona Complex, Anglesey
2013
Domainal trace lineation is defined by the intersection of two foliations, where at least one of these foliations is a composition banding formed by deformational processes (e.g. differentiated crenulation cleavage). The diagnostic feature of this lineation is a pronounced striping observed on the foliation surface that intersects the banding. An example of domainal trace lineation is displayed on the dominant foliation surfaces in New Harbour Group metasediments, near Rhoscolyn, Anglesey. The lineation is produced by the intersection of two foliations of domainal type, which produces prismatic domains resembling stretched objects. This probably explains the previous identifications of the lineation as a stretching lineation. The new interpretation of the lineation has potentially important implications for the deformation history of the New Harbour Group.
Journal Article
Deciphering the geology of some Darriwilian–Sandbian (Ordovician) ‘ghost’ formations in the UK and North America using olistoliths in marine debris flows
2018
Olistostromes with calcareous olistoliths are rare components in the Ordovician successions in NW Europe and North America, having been described from only a small number of localities. One of the best exposed, but least known, is in the Garn Formation in coastal outcrops in Anglesey in northwestern Wales. Here, in the graptolite-bearing shales of the Garn Formation, there are numerous limestone olistoliths that are derived from an otherwise unknown ‘ghost’ formation whose original depositional site remains an enigma. These olistoliths contain a Baltoscandian type of conodont fauna that is otherwise unknown in Wales and England. It represents the Baltoniodus variabilis Subzone of the Amorphognathus tvaerensis Zone. Similar, but slightly older, conodont faunas are recorded from olistoliths in the Tweeddale Member of the Shinnel Formation in southern Scotland and in probable olistoliths of the Cobbs Arm Limestone in northeasternmost Newfoundland. Approximately coeval conodont faunas are present in calcareous olistoliths in the Woods Hollow Shale of West Texas and the Womble Shale in the Ouachita Mountains of Arkansas, USA. Lithological and conodont evidence indicates that the calcareous olistoliths were derived from carbonate sediments deposited in relatively shallow water. It is concluded that the study of ‘ghost’ formation olistoliths may provide otherwise unavailable but important data bearing on the marine depositional history of a particular region.
Journal Article
Early Neoproterozoic limestones from the Gwna Group, Anglesey
2011
Limestone megaclasts up to hundreds of metres in size are present within the Gwna Group melange, North Wales, UK. The melange has been interpreted as part of a Peri-Gondwanan fore-arc accretionary complex although the age of deposition remains contentious, proposals ranging from Neoproterozoic to Early Ordovician. This paper uses strontium isotope chemostratigraphy to establish the age of the limestone blocks and thus provide a maximum age constraint on melange formation. Results show that, although the carbonates are locally dolomitized, primary 87Sr/86Sr ratios can be identified and indicate deposition sometime between the late Tonian and earliest Cryogenian. This age is older than that suggested by stromatolites within the limestone and indicates that the limestone did not form as cap carbonate deposits.
Journal Article
Terrane analysis along a Neoproterozoic active margin of Gondwana; insights from U-Pb zircon geochronology
by
Nance, R. D
,
Collins, A. S
,
Murphy, J. B
in
absolute age
,
accretionary wedges
,
active margins
2007
The tectonic affinities of terranes in accretionary orogens can be evaluated using geochronological techniques. U-Pb zircon data obtained from paragneisses of the Coedana Complex (Anglesey) and the Malverns Complex, southern Britain, indicate that they were deposited during the mid- to late Neoproterozoic and have a comparable Amazonian provenance. Metamorphism of the Coedana gneisses occurred at 666±7 Ma, similar to the age of metamorphism in the Malverns Complex. Anglesey therefore probably evolved in proximity to the Avalonian basement of mainland southern Britain during the mid- to late Neoproterozoic and is not a \"suspect terrane\" relative to the remainder of Avalonia.
Journal Article
Provenance and age constraints of the South Stack Group, Anglesey, UK; U-Pb SIMS detrital zircon data
2004
U-Th-Pb Secondary Ion Mass Spectrometry (SIMS) data from detrital zircons extracted from the South Stack Group, Anglesey, UK, indicate that: (1) the maximum depositional age of the Holyhead Formation (South Stack Group, Monian Supergroup) is 501±10 Ma; (2) the Monian Supergroup was deposited between c. 500 and 475 Ma and is part of the Cambrian-Lower Ordovician succession found in southern Britain and Ireland; (3) Avalonia was a major sediment source (age maxima at 543-552 and 604-627 Ma); (4) Amazonia probably also provided zircons (common Neoarchaean-Mesoproterozoic grains) weakening suggestions that Avalonia had rifted off Gondwana by Cambrian times.
Journal Article
The significance of the boundary between the Rhoscolyn and New Harbour formations on Holy Island, North Wales, to the deformation history of Anglesey
by
Woodcock, Nigel H
,
Treagus, Jack E
,
Treagus, Susan H
in
Anglesey Wales
,
basin analysis
,
Boundaries
2013
The boundary between the Rhoscolyn and New Harbour formations on Holy Island, Anglesey, has been described as a high strain zone or as a thrust. The boundary is here described at four localities, with reference to the contrasting sedimentary and deformational character of the two formations. At one of these localities, Borth Wen, sandstones and conglomerates at the top of the Rhoscolyn Formation are followed, without any break, by tuffs and then mudstones of the New Harbour Formation. It is concluded that there is clear evidence of depositional continuity across the boundary here, and that both formations subsequently shared a common two-phase deformation. The first (D1) was manifestly different in intensity and scale in the two formations, whereas the second (D2) produced very similar structures in both. The other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of Holy Island, leading us to identify two previously unrecognized major D1 folds in addition to the Rhoscolyn Anticline. At one of these localities (Holyhead), we confirm the presence of Skolithos just below the boundary, supporting radiometric evidence for a lower Cambrian or later age for the Rhoscolyn Formation. A turbidite interpretation for both the Rhoscolyn and New Harbour formations best fits the available evidence. A deep-water depositional environment is still compatible with the sporadic presence of Skolithos burrows, but less so with reported observations of hummocky and swaley cross-stratification lower down the South Stack Group.
Journal Article
Major folds affecting the Lower Old Red Sandstone Group at Lligwy, Anglesey, North Wales, and their regional significance
by
TREAGUS, SUSAN H.
,
TREAGUS, JACK E.
,
WOODCOCK, NIGEL H.
in
Acadian Phase
,
Anglesey
,
anticlines
2011
The Old Red Sandstone on Anglesey, North Wales, presumed Lower Devonian in age, is folded and locally cleaved, but the intensity of this deformation has previously been understated. We describe two S-verging anticline–syncline pairs, one with a strongly overturned middle limb, their associated minor folds and an axial-planar cleavage. The intensity of the deformation calls into question a proposed link to Variscan fault displacements, and the angular unconformity below the Old Red Sandstone precludes the deformation being part of a continuous ‘late Caledonian’ phase. We consider this deformation of the Old Red Sandstone to be mid-Devonian, correlating with the Acadian phase in mainland Wales. It is predated by a Silurian shortening deformation on Anglesey that is possibly related to the closure of the Iapetus Ocean, absent in mainland Wales and the Lake District, but perhaps preserved also on the Isle of Man.
Journal Article
A Soil Trail?—A Case Study from Anglesey, Wales, UK
2010
Geodiversity includes not just rocks and major geological features, it also embraces soft sediments and landscape features. This paper demonstrates how soil profiles can be promoted within geoheritage as an important feature of the aesthetics of the landscape as well as being vital to support biodiversity and many environmental functions including pollution abatement, climate change and food production. Their importance is recognised increasingly by scientists and policy makers but there is great diversity of soil types that often goes unrecognised, and hence soils are not always used appropriately. Whilst writing a guide to the coastal footpath around Anglesey, it became obvious that there are numerous opportunities to view the soil exposed on cliff edges and this prompted the idea of a trail leaflet for walkers and the interested public. This paper summarises the range of soils on view and how they support different land uses and form the underlying reason for the diversity of the landscape.
Journal Article