Geological landscape character assessment, Northumberland National Park and surrounding area

This report describes work carried out by BGS as part of the wider Northumberland National Park Authority Land Characterisation Project. It incorporates an innovative method of categorising the geological contribution to the physical landscape and was undertaken in association with a geodiversity audit of the area. Data from the study was provided to the Authority for incorporation in its GIS. Further description of the landscape will be included in the reports arising from the Geodiversity study

Joint-bounded crescentic scars formed by subglacial clast-bed contact forces: implications for bedrock failure beneath glaciers

Glaciers and ice sheets are important agents of bedrock erosion, yet the precise processes of bedrock failure beneath glacier ice are incompletely known. Subglacially formed erosional crescentic markings (crescentic gouges, lunate fractures) on bedrock surfaces occur locally in glaciated areas and comprise a conchoidal fracture dipping down-ice and a steep fracture that faces up-ice. Here we report morphologically distinct crescentic scars that are closely associated with preexisting joints, termed here joint-bounded crescentic scars. These hitherto unreported features are ca. 50–200 mm deep and involve considerably more rock removal than previously described crescentic markings. The joint-bounded crescentic scars were found on abraded rhyolite surfaces recently exposed (< 20 years) beneath a retreating glacier in Iceland, as well as on glacially sculpted Precambrian gneisses in NW Scotland and various Precambrian rocks in Ontario, glaciated during the Late Pleistocene. We suggest a common formation mechanism for these contemporary and relict features, whereby a boulder embedded in basal ice produces a continuously migrating clast-bed contact force as it is dragged over the hard (bedrock) bed. As the ice-embedded boulder approaches a preexisting joint in the bedrock, stress concentrations build up in the bed that exceed the intact rock strength, resulting in conchoidal fracturing and detachment of a crescentic wedge-shaped rock fragment. Subsequent removal of the rock fragment probably involves further fracturing or crushing (comminution) under high contact forces. Formation of joint-bounded crescentic scars is favoured by large boulders at the base of the ice, high basal melting rates, and the presence of preexisting subvertical joints in the bedrock bed. We infer that the relative scarcity of crescentic markings in general on deglaciated surfaces shows that fracturing of intact bedrock below ice is difficult, but that preexisting weaknesses such as joints greatly facilitate rock failure. This implies that models of glacial erosion need to take fracture patterns of bedrock into account

Glacial meltwater and groundwater interactions : evidence from the Virkisjokull observatory in Iceland

There is growing recognition of the important role that groundwater may have in buffering changes in river discharge due to increased melting of glaciers. Glacial deposits, particularly proglacial deposits and outwash plains can form significant aquifers and contain groundwater stores that are rarely quantified. In addition, interaction of basal melting of glaciers with groundwater can help to sustain flow through prolonged cold winters. The multidisciplinary BGS observatory at Virkisjökull in Iceland provides an excellent opportunity to characterise and quantify glacial meltwaters and groundwater. Glacier meltwater has been measured since September 2011, and precipitation and temperature from weather stations at varying altitudes since September 2009. Meltwaters and groundwater in the proglacial environment have been sampled periodically and analysed for inorganic chemistry, CFC, SF6 and stable isotopes to help understand the origin and flow paths of meltwaters and groundwater. The proglacial deposits have been mapped and the permeability of targeted deposits characterised. Initial findings show that the outwash plain provides a significant highly permeable aquifer, and is recharged locally from precipitation, with a growing influence of meltwater close to the meltwater channel. Shallow groundwater from snow melt within the catchment provides significant flow to the meltwater channels in spring, but in the prolonged winter, basal meltwater, possibly linked with sub glacial groundwater, helps to sustain flow in the meltwater channels. This initial study has led to the design of a more detailed experiment in the summer of 2012 involving the drilling and instrumentation of a targeted network of piezometers across the sandur and proglacial area

Northumberland National Park : geodiversity audit and action plan

The study and recommendations presented here represent the first attempt to address the varied facets of geodiversity within the Northumberland National Park and adjoining area, which for the purpose of this publication is called the district, shown on the inside front cover. Moreover, as the first comprehensive Geodiversity Audit and Action Plan prepared specifically for any of the 14 National Parks in Great Britain, it is hoped that this publication will serve as an example of good practice for other National Parks and protected areas. The importance of the rich natural and historical heritage and the need to ensure protection of this precious resource are fundamental to the sustainable management of the Northumberland National Park. Some aspect of earth science impacts upon almost every facet of the district’s character. Policies for the better protection and understanding of wildlife, cultural and historical issues are already in place for the National Park. To these must be added policies designed to understand, protect and interpret the area’s equally rich geodiversity. The Northumberland National Park Authority published its first Biodiversity Action Plan in 2000, since when it has been working in partnership with other agencies and land managers to achieve its objectives for biodiversity including seeking a more favourable conservation status for all the Park’s habitats and species. It is anticipated that this Geodiversity Action Plan will similarly provide the impetus for increased protection and enhancement of geodiversity and encourage the involvement of the local community. Additionally, as we improve our understanding of the role that geodiversity plays within the wider environment, and its influence on our wildlife, we can help ensure a positive future for species and their habitats as they respond to a changing world

Author Correction: High-resolution record reveals climate-driven environmental and sedimentary changes in an active rift (Scientific Reports, (2019), 9, 1, (3116), 10.1038/s41598-019-40022-w)

This Article contains errors in Reference 40 which is incorrectly given as: Palyvos, N., Pantosti, D. &amp; Zabci, C. Paleoseismological evidence of recent earthquakes on the 1967 Mudurnu Valley earthquake segment of the North Anatolian fault. Bull. Seis. Soc. Am. 97, 1646–1661 (2007). © 2019, The Author(s)

Estimating the hidden number of scrapie affected holdings in great Britain using a simple, truncated count model allowing for heterogeneity

None of the current surveillance streams monitoring the presence of scrapie in Great Britain provide a comprehensive and unbiased estimate of the prevalence of the disease at the holding level. Previous work to estimate the under-ascertainment adjusted prevalence of scrapie in Great Britain applied multiple-list capture-recapture methods. The enforcement of new control measures on scrapie-affected holdings in 2004 has stopped the overlapping between surveillance sources and, hence, the application of multiple-list capture-recapture models. Alternative methods, still under the capture-recapture methodology, relying on repeated entries in one single list have been suggested in these situations. In this article, we apply one-list capture-recapture approaches to data held on the Scrapie Notifications Database to estimate the undetected population of scrapie-affected holdings with clinical disease in Great Britain for the years 2002, 2003, and 2004. For doing so, we develop a new diagnostic tool for indication of heterogeneity as well as a new understanding of the Zelterman and Chao's lower bound estimators to account for potential unobserved heterogeneity. We demonstrate that the Zelterman estimator can be viewed as a maximum likelihood estimator for a special, locally truncated Poisson likelihood equivalent to a binomial likelihood. This understanding allows the extension of the Zelterman approach by means of logistic regression to include observed heterogeneity in the form of covariates-in case studied here, the holding size and country of origin. Our results confirm the presence of substantial unobserved heterogeneity supporting the application of our two estimators. The total scrapie-affected holding population in Great Britain is around 300 holdings per year. None of the covariates appear to inform the model significantly