Andrew McMillan

Classification of artificial (man-made) ground

Abstract The legacy inherited from anthropogenic processes needs to be addressed in order to provide reliable and up-to-date ground information relevant to development and regeneration in the urban environment. The legacy includes voids as well as anthropogenic deposits (artificial ground). Their characteristics derive from former quarrying and mining activities industrial processes creating derelict ground, variably consolidated made ground, and contaminated groundwater and soils. All need to be systematically assessed to inform the planning process and provide the basis for engineering solutions. Site-specific investigation needs to be conducted on the back of good quality geoscientific data. This comes from ‘field’ survey, remotely sensed data interpretation, historical maps, soil geochemical sampling, and geotechnical investigation. Three-dimensional and, in the future, four dimensional, characterization of superficial deposits is required to reach an understanding of the potential spatial lithological variability of artificial ground and the geometry of important surfaces, i.e. the boundary conditions. The classification scheme for artificial ground outlined in this paper and adopted by the British Geological Survey, will help in achieving this understanding.

The Moniaive Shear Zone: a major zone of sinistral strike-slip deformation in the Southern Uplands of Scotland

Synopsis The Moniaive Shear Zone is a recently delineated major zone of enhanced ductile deformation (up to 5 km wide) within the Southern Uplands of Scotland. The northern margin of the zone coincides with the Orlock Bridge Fault at the boundary between Ordovician and Silurian grey-wackes. Outwith the shear zone, the greywackes are typically weakly deformed, with the regional S1 fabric being developed within mudstone interbeds. Within the shear zone, Silurian Gala Group greywackes are deformed by locally pervasive linear and planar fabrics which yield a consistent sinistral sense of shear. The shear-zone fabric, in general, dips steeply towards the NW with its strike being sub-parallel to that of the regional S1 cleavage. Detailed petrological and micro-structural studies have demonstrated that the Moniaive Shear Zone comprises several zones of high strain enclosing lenticular domains of relatively low strain. The relationship between the Moniaive Shear Zone and the Cairnsmore of Fleet Granite indicates that the main phase of ductile movement on the zone occurred prior to 392 Ma although the exact age of ductile deformation on the shear zone is uncertain.

A provisional Quaternary and Neogene lithostratigraphical framework for Great Britain

This paper presents an overview of a provisional lithostratigraphical framework for the Quaternary and Neogene deposits of Great Britain (England, Scotland and Wales) (onshore). The objective is to provide a workable framework to aid future Quaternary mapping and research, and a stratigraphical scheme capable of use in a wide variety of applications. Using the full hierarchy, a supergroup, group and subgroup lithostratigraphy, based upon the primary mapping unit, the formation, is proposed. It is recommended that some classes of lithogenetically-defined deposits which, at present cannot be accorded formational status, should be assigned informally to one of the proposed groups or subgroups. The framework distinguishes one superficial deposits supergroup within which seven groups are defined: i) Crag Group, marine deposits (Late Pliocene to Early Pleistocene); ii), Dunwich Group, fluvial deposits (pre-Anglian/pre-Elsterian); iii) Residual Deposits Group; iv) British Coastal Deposits Group, coastal and marine deposits (Anglian to Holocene); v) Britannia Catchments Group, fluvial, organic and mass movement deposits (Anglian to Holocene) within broadly defined catchment areas related to Late Devensian to present-day physiography; vi) Albion Glacigenic Group, glacigenic deposits (pre-Devensian/pre-Weichselian), and vii) Caledonia Glacigenic Group, glacigenic deposits (Devensian/Weichselian). North of the Devensian (Weichselian) ice-sheet limit, a series of glacigenic subgroups are defined geographically for the two glacigenic groups on the basis of mappable formations of till. The subgroups include associated formations of glaciofluvial and glaciolacustrine deposits. Consequently some of the glacigenic water-lain units may extend beyond the Devensian limit. Catchment subgroups of the Britannia Catchments Group are proposed for formations and lithogenetic units defined within broad present-day physiographic regions by major river drainage systems that have developed since Middle Pleistocene time. Lithostratigraphical description and correlation of formations will aid the refinement of the proposed framework and enable the development of lithostratigraphical maps and three-dimensional models. As well as offering a unified framework for onshore Quaternary and Neogene deposits the proposed supergroup, group and subgroup structure may prove useful for a wide range of regional applications (e.g. hydrological, hydrogeological, engineering).

Onshore Quaternary geological surveys in the 21st century: a perspective from the British Geological Survey

Abstract At the turn of the century the British Geological Survey has embarked on a major programme to construct a 3-dimensional geological model of the UK. The reassessment of methodologies used to investigate Quaternary deposits and processes forms an important part of this programme. Surveys of user requirements indicate that the collation of new data and the generation of new output are needed to meet the diverse needs of society such as information on the geometry of sediment bodies, their lithologies, geotechnical properties and permeability, the rockhead surface, slope stability, land susceptible to flooding, coastal sediments, contaminated land and artificial deposits. These initiatives are driven by the recognition that the dynamic Quaternary record, reflecting the effects of recent climate and neotectonic change has both short- and long-term relevance to the use of information on the natural environment in which we live.

Permo–Triassic rocks in boreholes in the Annan-Canonbie area, Dumfries and Galloway, southern Scotland

Synopsis Recent boreholes provide new data on the sequence, age, lithology and geophysical log stratigraphy of Late Permian and Early Triassic strata on the northern edge of the Carlisle Basin. Late Permian evaporites (gypsum-anhydrite) and microfloras are recorded and described for the first time in onshore Scotland. The lower, argillaceous and evaporite-bearing strata are assigned to the Eden Shales Formation and are divided into three informal lithostratigraphical units, in ascending order ES1, ES2 and ES3. The Eden Shales grade upwards into the St Bees Sandstone Formation. The strata closely resemble those in neigh-bouring Cumbria, and help to refine some details of regional palaeogeography and correlation. Regional log correlation suggests that a significant evaporite-bearing Late Permian section is missing, probably cut out by faulting, in the Silloth-1A Borehole, the main deep borehole penetrating the Carlisle Basin.

Glasgow, a case study in urban geology

A long history of mining and quarrying in Glasgow has left a legacy of engineering problems. Thematic mapping by the British Geological Survey, which takes account of all the available evidence on the distribution of man-made hazards and relevant geological factors, is assisting local and national planning departments in the preparation of proposals for urban renewal and development. Key features described include: lithology, thickness and generalized engineering properties of the drift deposits; bedrock geology; and undermining, with the emphasis on workings close to rockhead.

Lithostratigraphical subdivision of the Sherwood Sandstone Group (Triassic) of the northeastern part of the Carlisle Basin, Cumbria and Dumfries and Galloway, UK

Synopsis Two formations, the St Bees Sandstone and Kirklinton Sandstone, have been mapped in the past within the Triassic Sherwood Sandstone Group of the eastern part of the Carlisle Basin, Cumbria, and adjacent parts of Dumfries and Galloway, UK. However, previous workers have found considerable difficulty in consistently identifying, defining and mapping the Kirklinton Sandstone Formation. The principal lithological change within the Sherwood Sandstone Group is between mainly fine-grained sandstones that are commonly micaceous and contain numerous mudstone interbeds in the lower and middle parts of the group, and fine- to coarse-grained sandstones with rare or no mica and few mudstone partings at the top of the group. This change occurs within the Kirklinton Sandstone Formation as previously mapped. This paper considers ways of subdividing the group lithostratigraphically and the nomenclature to be adopted. All options have some associated problems, but, in view of the recently determined similarities with the contiguous sandstones offshore, the adoption of the same terminology as that in the adjacent East Irish Sea and Solway Firth basins is suggested, i.e. the St Bees Sandstone Formation below (subdivided where possible into Rottington Sandstone and Calder Sandstone members) and the Ormskirk Sandstone Formation above.

Regional geochemical patterns in SE Scotland: source lithology, inheritance and glacial overprinting

Synopsis The Lower Palaeozoic Southern Uplands terrane shows a NE–SW, strike-parallel coincidence of regional geochemical lineaments defined from stream-sediment data, and major lithostratigraphically significant structures. West of Moffat, Silurian strata of the Gala and Hawick groups are divided by geochemical lineaments coincident with the Laurieston Fault. East of Moffat, the geochemical lineaments diverge towards the NE with Gala-type regional geochemistry (high Sr and Ba, low CaO) to the north of the Moffat Valley Fault, whilst Hawick-type regional geochemistry (low Sr and Ba, high CaO) continues to the south of the Laurieston Fault; between the faults lies the recently-defined Ettrick Group. Beyond the eastern end of the Lower Palaeozoic outcrop, its geochemical lineaments extend across the unconformable cover of Devonian ‘Old Red Sandstone’. This is partly a drainage catchment effect, but two other possible explanations are considered: a localized derivation of the Devonian clastic rocks, such that they inherit the compositional patterns of the underlying Lower Palaeozoic sandstones; or a geochemical signature imposed by glacial deposits derived from the Lower Palaeozoic outcrop. The local effect of glacial dispersion is confirmed by the distribution of TiO2; anomalously high levels associated with Carboniferous mafic lavas have been transported NE across the low-TiO2 Carboniferous sedimentary rocks of the Tweed Basin.

The role of the British Geological Survey in the history of geoconservation

Abstract Over its 172 year history, the British Geological Survey (formerly the Geological Survey of Great Britain) has, through underpinning core activities, its archive and databases and its experienced field staff, provided the geological basis for geoconservation. Evolving activities of the Survey from primary survey and collecting to revision mapping to 3D/4D-modelling reflect changing national needs. In turn, BGS has developed its capability to provide new geological interpretations and a range of publications raising the profile of Earth sciences, both for professionals and for the popular market. Today, BGSs input through networks to geodiversity projects and to newly designated regions such as Geoparks marks a major transition towards a proactive geoconservation agenda in the twenty-first century.

Towards understanding the Dumfries Basin aquifer, SW Scotland

Abstract The Dumfries Basin aquifer supports groundwater abstraction for public supply, agriculture and industry. Abstraction is concentrated in the western part of the basin, where falling groundwater levels and deteriorating water quality both reflect the effects of intense pumping. There are two bedrock units: a predominantly breccia-coarse sandstone sequence in the west, interfingering with a predominantly sandstone sequence in the NE and east. The basin is bounded by weakly permeable Lower Palaeozoic rocks, and is largely concealed by variable superficial deposits. Surface water flows onto the basin from the surrounding catchment via the Nith and the Lochar Water and their respective tributaries. Direct rainfall recharge occurs via superficial sands and gravels, especially in the north, and discharge is predominantly to the rivers in the central area rather than the sea. A picture is developing of two main aquifer types within the basin: the high-transmissivity western sector underlain by a fracture-flow system with younger water and active recharge and a high nitrate content, compared with the east where groundwater residence times are longer and the storage capacity is higher.