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GSI Metadata Bedrock Geology of Ireland 1:500,000 Scale |
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1.Metadata Reference
Metadata Date (dd/mm/yyyy): 13/06/2005
Last Date (dd/mm/yyyy): 22/06/2005
2.Indentification Information:
Title: 1:500,000 Bedrock Geology of Ireland
Description: This data represents a seamless bedrock geological dataset encompassing Rep of Ireland and parts of Northern Ireland at the 500,000 scale. The dataset comprises 3 key shape files: 1) GSI500K_Geology.shp A polygon shapefile that contains bedrock geological information on unitnames and descriptions.2) faults.shp. A linework shapefile that contains structural geological linework codes and fault names.3) Tertiary_dykes.shp a linework shapefile that contains representation of Palaeogene dolerite dykes.
Version1: 1.0
Language: English.
Keywords: Geology, bedrock geology, structural geology, 1:500,000 bedrock, geology, GSI, RockUnits, Unitnames.
Data type: vector.
3.Lineage Information
Originator org- Bedrock section of the Geological Survey of Ireland.
Other contributors.- Additional data supplied from the GSNI.
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
Principle data capture Technique-
This geological dataset was derived directly from the seamless digital bedrock 1:100,000 maps.
4. Lineage Records
4.1 Filenames : Seamless 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
It was decided to join all the maps together into a seamless in ArcView. Each map sheet commenced in ArcInfo generated new geological coverages representing Stratigraphy, Lithology, Igneous, Diagenetic, Dynamic, Thermal, and Geological Linework. All ArcInfo coverages were converted to shapefile format.
Methodology
Joining all the maps together into a seamless in Arc View 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 customised in Arc GIS. All relevant symbology was created and customised 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.
Scripts/tools used
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.
ArcInfo 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.
Contact details for further information on scripts/Tools.-
4.2 Filenames : The dataset comprises 3 key shape files: 1) GSI500K_Geology.shpfaults.shp and 3) Tertiary_dykes.shp .
Date (dd/mm/yyyy) 07/12/2004
Originator Bedrock Section of The Geological Survey of Ireland
Nature of change/update to data
Geological unit polygons in a copy of the seamless 100k map were edited and adapted to the 500k scale. A field with new unit codes was entered in the attribute table.
Methodology
Geological unit polygons in a copy of the seamless 100k map were merged using the Newcode field. Each Newcode unit was assigned to one of about 74 map units for the 500k scale. A field for this unit code was entered in the attribute table, and polygons merged using this field. A similar process was used on a digital version of the GSNI 1:250,000 maps to fill in the remaining part of Northern Ireland and polygons merged along the join. Polygons were edited to remove holes of small lakes and rivers, merge and simplify polygons too small for the 500k scale and smooth some lines.
Sources Used as input Data for the Change /update.-
This dataset is derived from the seamless bedrock geology at the 1:100,000 scale.
Scripts/tools used.-
Editor toolbar (merge, editing nodes and splitting 100k polygons on a scientific/geological level).
Contact details for further information on scripts/Tools.-
Brian Mc Connell, Bedrock Section of the Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4.
4.3 Filenames : The dataset comprises 3 key shape files: 1) BED500K_topo_060307.shpfaults.shp and 3) Tertiary_dykes.shp.
Date (dd/mm/yyyy) 06/03/07
Originator Bedrock Section of The Geological Survey of Ireland
Nature of change/update to data
A new topology was created and from it the geological unit polygons edited. Irrelevant fields were deleted and new ones containing "area" values and new unitnames ("unit_ames2") were added.
Methodology
A personal database topology called "Bed500k_Topology""was created from bed500k geodatabase feature class. Points, area and line errors were highlighted and the topology was edited using the topological tool. Thus, gaps were and overlapping features edited or reclassified, to be consistent with the geological polygons and line structural geology pattern. Lakes, Islands and some bits of the coastline were reclassified as "exceptions" as there are not truly gap errors. Once the gaps and overlaps were fixed the topology was validated using the validating button. A few more errors, originated during the topological editing process were amended. From ArcCatalog, the new correct topology was exported into a single shapefile feature and saved under the "BED500K_topo_060307.shp" name. Shape_ area and shape_lengh fields were deleted. A new field called "area_km2" was added to the attribute table and values within were calculated using the calculating values option. From the selecting by attributes option a double check was made to ensure that the file was totally cleaned. Two inconsistencies were found in polygon 74 and 85, which did not correspond to any polygon feature on the map and were therefore eliminated. "Unit_name" field was examined, it was found out that descriptions given under this field did not match with those on the original unit_name field (from file Bed500k.shp) and inturn would not match with the associated style file. From the attribute table a new field called "Unite_name2" was created. BED500K_topo_060307.shp file and old file Bed500k.shp, which contains accurate names under the unit_name field, were join using the "natmapcode" as a link field. Finally unit names were checked and redescribed. Table joins were removed after. Using the "Unit_name2" a style file "500kbed.style" was applied and the new map coloured. Sources Used as input Data for the Change /update.- bed500k.shp,Dykes500k.shp,Faults.shp and Bed500k.shp
Scripts/tools used .-
Editor toolbar, Topology toolbar
Sources Used as input Data for the Change /update .- Brian Mc Connell, Bedrock Section of the Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4.
Contact details for further information on scrips/Tools.-
Brian Mc Connell, Bedrock Section of the Geological Survey of Ireland, Beggars Bush, Haddington Road, Dublin 4.
Authorised by : - Koen Verbruggen.
Organisation : Geological Survey of Ireland
Contact Address:
Principal Geologist
Geological Survey of Ireland,
Beggar's Bush,
Haddington Road ,
Dublin 4
Contact Email: gsisales@gsi
Contact Phone: 01-6782864
Website Details: http://www.gsi.ie
Maintenance/Update frequency : as needed.
6.Data dictionary File Name/Field Description/ Field Type
UnitName: Unit label and Name of the geological formation or member
Formation: Name of the geological formation or member /Field Type: Text
Natmapcode New code for the new merged polygons in order symbolize them/ Field Type:Short integer
Unit_Label : It is the number which the unit is labeled / Field Type: Short integer
Unit_table: Code referring to previous union of tables
Area_km2: Area of the polygons in km 2 / Field Type: Double
7.Geographical information
Reference system : Irish National Grid
Spatial Extent : Whole of Republic of Ireland and part of Northern Ireland. 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 : 1:500,000
8.Distribution Information
Filename: The 500k bedrock Geology comprises 3 key shape files: 1) GSI500K_Geology.shp faults.shp and 3) Tertiary_dykes.shp.
Holder: Geological Survey of Ireland.
Distributor contract details : Koen Verbruggen
Information Management,
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 .
File size: 9.53 MB .
Copyright: Use of the data is constrained only by the GSI GIS Data License Agreement.
Other Restrictions:
The geological dataset in under the copyright of the Geological Survey of Ireland. This map is purely representational and is designed for general information and strategic planning use only. Boundaries are interpolated on the basis of data available to the GSI at the time of compilation, from a variety of sources, and local details have been generalized to fit the map scale. The accuracy of data used or interpolations made, is neither stated nor implied. Evaluation of specific sites will normally require further and more detailed assessments, and will frequently require site investigations. Base maps at 1:100K are under GSI copyright.
9. Quality Ratings
Spatial Accuracy: Positional errors of up to 500m have been observed .
Thematic accuracy: Correct names added to geological structures and geological units formations .
Currency: Geometry and attributes are consistent with the real geological representation.
Logical consistency: This dataset is topologically correct using ArcGIS 8.3.