Tuesday, 17 February 2015

Georeferencing/Geolocating, GeoIndex and the BGS Maps Portal

It may be 18 months since the end of  official Jisc funding for the GB/3D Type Fossils Online Project, but development of this important resource has continued apace. Some of our volunteers have been georeferencing (or geolocating) many of the fossil localities. Georeferencing is the addition of a grid reference, or latitude and longitude, to a location, and it will be described in more detail in a forthcoming post. The aim of georeferencing is to allow localities to be plotted more easily on a map, or in a GIS (Geographical Information System), and then subjected to more rigorous analysis. As a geological survey, our traditional business has always been the production of geological maps, and not surprisingly, we are heavily involved in GIS. We have an online GIS known as “GeoIndex”, which provides access to many of our datasets and is available at: http://mapapps2.bgs.ac.uk/geoindex/home.html  .

BGS “GeoIndex” GIS: http://mapapps2.bgs.ac.uk/geoindex/home.html . Screen shot showing SW Scotland, the English Lake District and parts of the Isle of Man and Northern Ireland. Colours correspond to the BGS 1:625,000 scale Bedrock geology, and the triangles represent rock samples in the BGS Collections. Black triangles indicate online images of thin sections – both plane and cross polars. 
The BGS has recently made over 6000 geological maps and sections available through its online Maps Portal. The 1:50,000 (and previously 1:63,360) maps established a standard which many other geological surveys around the world have endeavoured to copy. Typical map sheets now include not only the basic map and key, but generally several cross-sections and a “generalised vertical section”. Some maps also include geophysical, metamorphic & biostratigraphic data, and a summary geological history.
Key “marginalia” on the Sidmouth Sheet (below) include:
  • Two horizontal cross sections, showing the general relations of the rocks along the two lines drawn on the map. The vertical scale is x2
  • Generalised vertical section. This acts as a key, drawn roughly to scale, indicating thickness variations, and the relationships between the solid geology lithostratigraphic units. Dominant lithologies are also described
  • Key to symbols and other units
  • Various location maps showing adjacent map sheets, component maps and survey dates
  • Surveying history and bibliographic reference
  • 2000/2005 –in the bottom left corner – indicates 2000 copies were printed in 2005

British Geological Survey 1:50,000 solid & drift geological map sheet 326 & part of 340 – Sidmouth. Published in 2005. http://www.largeimages.bgs.ac.uk/iip/mapsportal.html?id=1001815

The online maps portal is available at: http://www.bgs.ac.uk/data/maps/home.html . It allows you to select from the latest versions of the 1:50,000 geological maps, or many of the older versions, plus many other small scale maps and sections. For each map or section there is a detailed record of the metadata and links to view or buy the map. The link to view the map open a high resolution JPEG2000 image within the IIPMooViewer (IIPImage HTML5 Ajax High Resolution Image Viewer), which allows you to zoom in and move around the screen. At full magnification (typically around x3), you can see more on the image that you can on the original – at least without a magnifying glass.

    The BGS online maps portal, available at: http://www.bgs.ac.uk/data/maps/home.html 

    The inclusion of all the historical maps allows the user to appreciate the understanding of the geology and the stratigraphical nomenclature that would have been current at any point in time, for example when a particular fossil was collected. One of the key localities in the GB3D database is Lyme Regis, and I have included extracts from the 2005 and 1846 maps. I will leave the reader to compare the two.

    Close-up of the area around Lyme Regis. BGS 1:50,000 geological map sheet 326 & part of 340 – Sidmouth. Published in 2005. http://www.largeimages.bgs.ac.uk/iip/mapsportal.html?id=1001815

    Close-up of the area around Lyme Regis. Geological Survey of England and Wales 1:63,360 solid geological map, Sheet 22  – Coast from Lyme Regis to Torbay, Exeter, Newton Abbot, Totnes. Published in 1846. http://www.largeimages.bgs.ac.uk/iip/mapsportal.html?id=1000046

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