Alan Stevenson

Metal concentrations in marine sediments around Scotland: a baseline for environmental studies

Abstract Samples of sediment collected from the seabed by the British Geological Survey (BGS) have been analysed to measure their concentrations of metals. This information can be combined with our knowledge of the nature of the seabed sediments, the processes by which they are transported and deposited and the rocks from which they are derived, to provide a unique baseline of naturally occurring metals. In addition, the data can be used to assess the inputs of metals to the marine environment due to human activities. As the samples were collected during the 1970s and early 1980s they can contribute to assessments of the environment prior to the main phase of industrial activity at the Atlantic margin.

Slope Failures in the Faroe — Shetland Channel

Submarine slides varying from 0.002km3 to more than 360km3 have been identified in the Faroe — Shetland Channel using a wide range of surveys. Although not a major constraint to seabed use slides need to be considered as a potential geohazard. Dynamic loading of contouritic horizons is considered the triggering mechanism of these thin layer failures.

Seabed mapping for the 21st century : the Marine Environmental Mapping Programme (MAREMAP): preface

During the 1970s and 1980s, the British Geological Survey (BGS) carried out systematic surveys of the seabed and subseabed around Britain, as part of a Government-funded programme to map the UK Continental Shelf (UKCS). Using an array of sampling, coring and seismic profiling equipment, the programme resulted in a series of geological maps and scientific publications which described the sediments at the seafloor, the sediments deposited during the Quaternary glaciations, and the older sedimentary, igneous and metamorphic rocks. These systematic surveys of the UKCS were followed during the 1990s by BGS and industry co-funded surveys in the deep-water areas to the west of the UK, such as the Rockall Trough and Plateau; although here, the density of sampling, shallow boreholes and seismic surveys was significantly reduced.

National Programmes: Geomorphological Mapping at Multiple Scales for Multiple Purposes

A better understanding of marine geomorphology is a common goal for seabed mapping programmes, with various mapping approaches, methodologies and challenges associated with systematically describing geomorphological features. To address these issues, and highlight the overall value of geomorphological mapping, a group of representatives from the seabed mapping programmes of the geological surveys of Norway, Ireland and the United Kingdom have formed a partnership to share their knowledge, expertise and technologies. Here we describe the first year of collaboration by outlining the background to and motivation for the groups’ national seabed mapping programmes, and presenting several case studies as well as tests to potentially adopt a harmonised classification scheme.

Seabed Characterization - Developing Fit for Purpose Methodologies

We briefly describe three methods of seabed characterization which are ‘fit for purpose’, in that each approach is well suited to distinct objectives e.g. characterizing glacial geomorphology and shallow glacial geology vs. rapid prediction of seabed sediment distribution via geostatistics. The methods vary from manual ‘expert’ interpretation to increasingly automated and mathematically based models, each with their own attributes and limitations. We would note however that increasing automation and mathematical sophistication does not necessarily equate to improve map outputs, or reduce the time required to produce them. Judgements must be made to select methodologies which are most appropriate to the variables mapped, and according to the extent and presentation scale of final maps.