Post-calculation checks of GSI3D models V2

This report describes methods for identifying, checking and remediating issues in GSI3D models post calculation using cross-sections and exported surface and thickness grids. These checks are to ensure that the outputted geometry of geological units bear a true resemblance to the lateral and depth extents of those units correlated in GSI3D. The cross-section checks and issues include: • Missing envelopes or cross-section correlations geometries • Lack of correlation nodes on cross-section lines • Wrongly attributed correlation lines in cross-section • Lack of constraint at envelope boundaries The surface and thickness grid checks and issue include: • Bulls-eyes from anomalous correlation points • Holes in the top and base calculated surface • Surface crossovers • Unnatural artefacts in modelled surfaces from cross-section

The construction of a bedrock geology model for the UK: UK3D_v2015

This report is available for download on the BGS UK3D web page to allow the reader to better understand the context and development of UK3D, a national network, or ‘fence diagram model’, of bedrock geology cross-sections. It also explains the development of the metadata underpinning the model and therefore supports use and understanding of UK3D. The pre-existing BGS GB3D model provided the only nationally consistent representation of the bedrock geology of Great Britain to depths of at least 1 km. The latest version of this model was released in 2014 as the GB3D_v2014 and accompanying report (Mathers et al. 2014b). However, the existing GB3D_v2014 model lacked equivalent scale presentation of a fence diagram model for Northern Ireland. It was recognised that in order to provide comparable geological information across the United Kingdom it was necessary to upgrade the model to a UK3D fence diagram model incorporating Northern Ireland, with rigorous peer review performed to enable an enhanced dataset. The objective of this study was therefore to further develop the GB3D model, outlined by Mathers et al. (2014a and b), into a UK3D model by the incorporation of 36 deep boreholes and a framework of 15 cross-sections for Northern Ireland. The appropriate applications for the revised model are for geoscience communication and education to illustrate the national and regional bedrock geology of the United Kingdom to a depth of at least 1 km with an intended resolution of use in the 1:250 000 to 1:1 million scale range. Limitations inherent in the model preclude such applications as detailed geological assessments, resource-reserve estimation and exploration, and any representation or use outside the intended resolution range. The new model produced by this study UK3D_v2015 supersedes the earlier 2014 version for England and Wales, for which areas of the fence diagrams remain the same. The Scottish portion of the model remains unchanged from the earlier 2012 version. The new dataset is a wholly owned BGS product and as with its forerunners it is freely available from the BGS website http://bgs.ac.uk as downloads in a variety of formats

Enhanced mapping of artificially modified ground in urban areas : using borehole, map and remotely sensed data

The report described here is focused on how using boreholes and attributes from boreholes increased and enhanced the mapping of Artificially Modified Ground, and helped measure landscape evolution change in the urban environment. These attributes from boreholes include the presence of AMG in a borehole, the thickness of AMG recorded, the start height of a borehole and the location of boreholes (and other boreholes in close proximity) with modern topological features and geological maps

Enkoping Esker Pilot Study : workflow for data integration and publishing of 3D geological outputs

This report describes the workflows for preparing the data for constructing and publishing a geological model of the Enköping Esker, Sweden. This pilot study was a collaborative effort between the British Geological Survey (BGS) and Swedish Geological Survey (SGU). The main role of the BGS was to help prepare the data for the geological model, provide advice about the construction of the model, technical check the model and create the publication methods for the dissemination of the model. The main role of SGU was to construct the geological model using the SubsurfaceViewer software (INSIGHT). The following publication methods were deployed: Synthetic Geological Model Web Viewer Minecraft 2D and 3D shapefiles ASCII grids (Top, Base, Thickness and Rockhead (base of superficial deposits)) Groundhog Desktop compatible project files and set up GeoVisionary v3 compatible project files and set up Subsurface Viewer files GOCAD-SKUA surfaces (.ts) – top, base and shells A number of suggestions were made by the BGS to improve the workflow methodology. These included: Using Groundhog in the initial stages of model development to minimise snapping and model checks in cross-section Bathymetry would have improved the modelling of the distribution of superficial deposits at the lake bed surface Using the Unlithified Coding Schema (Cooper et al 2006) for the coding of boreholes Ensuring that the borehole index information is correct (start heights) which can reduce the error in the elevations when correlating stratigraphy Looking at stochastic methods for modelling lithofacies in eskers Developing simple visualisations of uncertainty in 2D based on quantitative informatio

The London Basin superficial and bedrock LithoFrame 50 Model

This report describes the methodology and datasets used in the construction of the 1:50 000 resolution superficial and bedrock geological model of the London Basin. The London Basin study area was divided into twelve 20 x 20 km tiles, with construction of the first tiles beginning in 2006 and completion of the combined model in 2014. This time period coincided with the ongoing development of GSI3D software which was used to construct much of the model. The GSI3D software was used to calculate a rockhead (base Quaternary and Anthropocene) surface that was then used as a capping surface for the modelling of the bedrock geology in the GOCAD® software. The model complements the corresponding DiGMapGB-50 tiles of the area and consists of about 80 modelled geological units, comprising mass movement (landslip), artificial, superficial, and bedrock. This report supersedes an earlier report detailing the construction of the superficial part of this model (Burke et al. 2013). A glossary of technical terms used is included at the end of this report

Specification of in- and output data formats and deliverables for commissioned 3D geological models

This document is intended to inform project managers, modellers, business development and delivery team members when preparing bids for externally commissioned 3D geological modelling projects and to reduce risk to BGS. The exact details are likely to be different with each modelling project, especially dependant on the methodological approach taken (Groundhog/GSI3D/GOCAD-SKUA). It is therefore essential to consult with the authors of this document as well as with contracts and IPR before submitting any documents to potential clients. The following sections include statements (in Italics) that may be appropriate for inclusion in modelling-related bids

A geological model of London and the Thames Valley, southeast England

Many geological survey organisations have started delivering digital geological models as part of their role. This article describes the British Geological Survey (BGS) model for London and the Thames Valley in southeast England. The model covers 4800 km2 and extends to several hundred metres depth. It includes extensive spreads of Quaternary river terraces and alluvium of the Thames drainage system resting on faulted and folded Palaeogene and Cretaceous bedrock strata. The model extends to the base of the Jurassic sedimentary rocks. The baseline datasets used and the uses and limitations of the model are given. The model has been used to generate grids for the elevation of the base of the Quaternary, the thickness of Quaternary deposits, and enabled a reassessment of the subcrop distribution and faulting of the Palaeogene and Cretaceous bedrock units especially beneath the Quaternary deposits. Digital outputs from the model include representations of geological surfaces, which can be used in GIS, CAD and geological modelling software, and also graphic depictions such as a fence diagram of cross-sections through the model. The model can be viewed as a whole, and be dissected, in the BGS Lithoframe Viewer. Spatial queries of this and other BGS models, at specific points, along defined lines or at a specified depth, can be performed with the new BGS Groundhog application, which delivers template-based reports. The model should be viewed as a first version that should be improved further, and kept up to date, as new data and understanding emerges

A 3D geological background for Knowsley Industrial Park and surrounding areas, NW England

This report describes the results of a study carried out by the British Geological Survey (BGS) on behalf of the Environment Agency NW to investigate the underlying geology beneath Knowsley Industrial Park, Merseyside, NW England. The overarching aim of the project was to establish a 3D geoscience framework beneath the Knowsley Industrial Park to enable the Environment Agency (the Agency) to assess the vulnerability of the underlying Sherwood Sandstone aquifer. The vulnerability of the aquifer to pollution from current and historic contamination of land, potentially leaking foul sewers and contaminated surface water drains could then be assessed by reference to the underlying geology. In addition to the 3D geological model, United Utilities pipeline data for foul and surface water drainage was provided by the Agency. This pipeline information was analysed and integrated with the geological data to provide an assessment of the potential linkage between the pipes and the underling bedrock or superficial geology in which they are sited. Over 300 additional paper borehole records were provided by the Agency from previous environmental site investigations carried out in the industrial park and incorporated into the BGS databases. In total, 1279 coded boreholes were used in the study. Of these, 733 were used to construct 58 geological cross-sections. The 3D geological model revealed a sequence of superficial deposits across the site comprising glacial, post-glacial and artificial deposits overlying the Sherwood Sandstone Group, that in places are deeply weathered to form loose sand. In the south-east and north-west of the site, rocks belonging to the Sherwood Sandstone Group crop out at surface. The vulnerability of the Sherwood Sandstone aquifer beneath the site, to pollution from contaminated water, depends in part on the distribution and thickness of weakly permeable superficial deposits such as clay or silt. The geological model has revealed that till is the only clay dominated unit present beneath the site and for this reason, invert levels of foul and surface water pipes were compared to this geological deposit as it may influence the potential vulnerability of the underlying aquifer. Invert levels represent the elevation of the base of the pipe. 4722 pipeline segments were analysed and classified according to their minimum invert level (representing the maximum depth below ground level) recorded for each segment. This information was used to identify pipeline segments that occurred above, below or within till. Pipeline segments interpreted to lie within or above the till were subdivided according to whether they were underlain by greater or less than 2.5 m of till. 2.5 m represents the average thickness of till calculated from the 3D geological model. Pipeline segments whose invert level occurs beneath the till will lie directly within the Sherwood Sandstone aquifer or sand and gravel dominated superficial deposits and therefore the relative hazard potential may be higher than those where clay dominated superficial deposits occur between them and the underlying aquifer. In general, the results indicate that the northern part of Knowsley Industrial Park and the northwestern part of the wider project area are underlain by greater than 2.5 m of till and that pipelines lie above the top surface of the till or within it. In contrast, the southern part of Knowsley Industrial Park and the south-western part of the wider project area are underlain generally by less than 2.5 m of till and pipeline segments occur below the till or directly within the Sherwood Sandstone aquifer. This information can be used as a preliminary screening or prioritisation tool. It can identify potential areas where the Sherwood Sandstone aquifer is most vulnerable to pollution from contaminated groundwater from poor condition, potentially leaking sewers and drains in the subsurface

A 3D geological model for B90745 North Trans Pennine Electrification East between Leeds and York

This report and accompanying 3D geological model were produced for Tata Steel Projects. The report describes the bedrock and Quaternary geology of the study area, comprising 28 km (17.5 miles) of railway line between Leeds and York. The description and spatial distribution of each geological unit is based on the 3D geological model, which was constructed using 1:10,000 scale digital geological map data and 102 borehole logs from the British Geological Survey’s national archive. All boreholes located within the modelled area were considered in the construction of the geological model, together with key boreholes that fall outside the area of study. The top and base of weathered rock as defined is depicted as layers within the model

Quantifying anthropogenic modification of the shallow geosphere in central London, UK

The veneer of artificial (anthropogenic) deposits present beneath contemporary cities is commonly markedly heterogeneous, particularly in cities such as London with a history of two millennia of development. To what extent can the analysis of borehole data, historical land use maps and digital terrain models provide adequate assessment of such heterogeneity? Two adjacent London boroughs, City of London and Tower Hamlets, are selected because of their contrasting historical development and current land use. Statistical comparison of the variations in deposit thickness is related to the natural Holocene topography, underlying geological deposits (non-anthropogenic deposits) and heights of overlying buildings. Estimates of the volume (~67 million m3) and mass (~100 million tonnes) of the deposits and additional volume (~359 million m3) and mass (~25 million tonnes) of buildings provides indication of additional loading that may cause local compaction or regional subsidence, a concern during a time of rising global sea level. Extrapolated across Greater London, the mass of anthropogenic deposits is estimated at ~6 billion tonnes. Assessment of the compositional variations within the artificial deposits provides an approximation of accumulation rates post-World War II. A potential event horizon, coincident with the early 1940s Blitz, could not be demonstrated as an extensive marker, but distinct lithological compositions for post-World War II strata are broadly coincident with the globally resolved signals marking the start of the Anthropocene Epoch