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GSI Metadata National Draft Generalised Bedrock Map for Groundwater |
Click Here to find out more about the Groundwater Section
Metadada Date (dd/mm/yyyy): 06/01/2004.
Last Date (dd/mm/yyyy): 19/02/2007.
Title: Grouped Rock Units / National Draft Generalised Bedrock Map for Groundwater
Description: This dataset contains bedrock Units created by grouping bedrock formations and members based on their hydrogeological properties and other factors.
Keywords - Rock unit group, Bedrock, Water Framework Directive, Groundwater, GSI, Geological Survey of Ireland.
Version: 1.0
Language : English
Data type: vector
Originator org - Groundwater Section (Geological Survey of Ireland)
Other contributors - Bedrock Section, Geological Survey of Ireland.
Technical contact details-
Contact Name : Silvia Caloca Casado
Organisation : Geological Survey of Ireland
Contact Address :
Information Management,
Geological Survey of Ireland,
Beggar's Bush,
Haddington Road ,
Dublin 4
Contact Email: Silvia.Caloca@gsi.ie
Contact Phone: 016782794
Contact Fax: 016681782
Website Details: http://www.gsi.ie
Principal data capture Technique - Derived from 100k seamless bedrock map; rock units/formations were grouped together based on expected similar hydrogeological characteristics.
4.1 . Filename.- Bedrock Geology of Ireland
This dataset comprises 6 key shape files: Final100kunion.shp, Final100kstra.shp, Final100kstru.shp, Cross100ksection.shp, Final100kmin.shp and 100kpoly.shp.
Date (dd/mm/yyyy) 19/11/2003
Originator Geological Survey of Ireland
Nature of change/update to data
All maps together into a seamless in Arc View . Each map sheet commenced in Arc Info generated new geological coverages representing Stratigraphy, Lithology, Igneous, Diagenetic, Dynamic, Thermal, and Geological Linework. All Arc Info coverages were converted to shapefile format.
Bedrock AutoCAD layers were converted to .dxf format and imported into Arc Info 7.x. For each map sheet Arc Info aml, filtered out relevant Bedrock AutoCAD layers to generate new Arc Info coverages. Each map sheet commenced in Arc Info generated new geological coverages representing Stratigraphy, Lithology, Igneous, Diagenetic, Dynamic, Thermal, and Geological Linework. All Arc Info coverages were converted to shapefile format.
In 2003 it was decided to join all the maps together into a seamless in Arc View, this involved Bedrock, Cartography and Information Technology and Groundwater Section. As the compilation of the series progressed over than a decade, some of the sheet boundaries inevitably did not match due to more recent interpretations as well as minor problems with the rasters not quiet matching. The geological interpretation was “fudged” in order to ensure that boundaries and polygons crossed sheet boundaries where appropriate and joined up.
Cartography introduced Arc GIS 8.x in 2002 to undertake necessary seamless geoprocessing exercise on map sheet-by-sheet basis. The following layers were utilised from original Arc Info coverage map layers: Stratigraphy, Igneous, Lithology, Diagenetic and Geological Linework.
The geological linework was divided into two separate shape files: Structural units and Stratigraphic units.
The original Arc Info coverages had a limited number of fields and did not possess unique code identifier. A new coding system was introduced to establish unique code field called 'NEWCODE'. All Bedrock section's data from their main database at this time (Dataflex) was converted to Microsoft Access. A procedure was then used to join and populate additional records as map sheets were added and merged.
Sheet joins and editing then commenced and quality control checks were introduced at interval and final stages. All relevant symbology was created and customized in Arc GIS. All relevant symbology was created and customized in Arc GIS.
Sources Used as input Data for the Change /update
Data capture & compilation from GSI Field Surveys in 1845 to 2003 performed by Bedrock Section. Data was collected both internally by GSI and also from external data sources.
Data in the form of six inch and one inch maps deposited by exploration companies along with borehole logs and locations were also used in the 1:100,000 compilations (data useful in the midlands Carboniferous).
The 1:100,000 series also used field surveys (mostly 6’’ to the mile) carried out in MSc/PhD mapping made available to GSI by Universities in Ireland and further a field.
Bedrock used AutoCad12 with their red book procedure on creation of geological layers.
CU used cartographic’ software ext. (A customised Arc Info module to facilitate map production process).
CU imported Bedrock data in DXF format and filtered layers in geological thematic GIS ‘coverages’.
Customised aml code was transparent and could be accessed and edited by CU.
Arc Scan ext . performed raster vector conversion preformed by heads up digitising.
Marginalia was greated by aml scripts and generated by Cartography.
Arc Info 7.x and AutoCAD tools.
Final100union.shp, Final100kstra.shp and final100stru.shp were imported into a featured set in an ArcGis Arcinfo 8.3 geodatabase. A topology was created for the final100kunion feature class with rules of “Must Not Overlap” and “Must Not have Gaps” with a cluster tolerance of one metre. Most errors related to the coastline, lakes and river channels. All errors were checked and fixed using the topology toolbar and Editor toolbar leaving 3514 “Must not have gaps” errors. The feature classes were then exported as a shapefile.
Andy Sleeman and Markus Pracht from the Bedrock Section and Eddie McMonagle from the Cartography Section of the Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4.
4.2.Filename .- Rockunits.shp
Date (dd/mm/yyyy).- 11/08/2003
Originator.- Groundwater Section of the Geological Survey of Ireland.
Nature of change/update to data
Twentyseven Rock Unit Groups were created by grouping over 1200 geological Formations and Members from the original bedrock geology file.
Methodology .- Arc GIS 8.3 Merge and Dissolve options were used to group polygons.
Sources Used as input Data for the Change /update .- Minor errors derived from original file have been detected and they are to be fixed in the future.
Authorised by : - Koen Verbruggen (IMP, Geological Survey of Ireland)
Maintenance/Update frequency : This file will not be updated.
6. Data dictionary. File Name/Field Description/ Field Type
Descript : Geological Unit name. Field type: String
Reference system : Irish National Grid
Spatial Extent : Whole of Republic of Ireland and part of Northern Ir part of Northern Ireland eland. Full extent in the data's coordinate system:
West longitude: 17937.271188
East longitude: 334513.68825
North latitude: 467259.844302
South latitude: 16333.179178
Additional extent: No height/depth/temporal info
Scale : 1:100,000
Filename : RockUnits.shp
Holder : Geological Survey of Ireland.
Distributor contract details : Koen Verbruggen
Information Management Programme,
Geological Survey of Ireland,
Beggar's Bush,
Haddington Road ,
Dublin 4
Storage Format : ArcGIS shapefiles.
Supply Format : ArcGIS shapefiles, MapInfo tabfiles.
Supply media : CD-Rom or email.
Filesize : 9.87MB, 7.92(winzip)
Copyright: Draft only to be used for water framework directive purposes. Use of the data is constrained only by the GSI GIS Data License Agreement.
Spatial Accuracy : Positional errors of up to 500m have been observed in datasets that have been used to create this file.
Thematic accuracy : Correct names have been assigned to the 27 Rock Unit groups. Some errors have been noticed at the Seamless 100k Bedrock map and consequently carried over into this file. There is also an "unclassified" class for areas of the map where geology is undefined
Currency : Digital geometry and attributes are based on the Groundwater Section new characterisation of the rock unit groups in terms of groundwater flow properties. For further information contact the Groundwater Section in the GSI.
Logical consistency : Data are topologically correct using ArcInfo 8.3. All polygons are closed. There are not gaps or overlaps.