OR/16/046 Appendix 4 - Appending additional data to BGS geology: 50k
| Armstrong, R, Daley, D, Lawley, R, Myers, A and Smith, A. 2016. User guide for the BGS geology: 50k dataset (v8). British Geological Survey Internal Report, OR/16/046. |
This section provides guidance on ‘add on’ datasets to the BGS Geology: 50k product.
An ‘add on’ dataset is a set of additional attributes that are applicable to the BGS Geology: 50k spatial data. They can be appended by using a database ‘join’ (a way of linking data) to extend the range or detail of the information available. They are sometimes called ‘look-up tables’, and are useful, because they are a compact way of storing data that is normally repeated many times within a dataset, or storing data that is used rarely, or only needed by a few users.
For BGS Geology: 50k there are currently two add-on datasets:
- Deprecated information (attribution previously supplied in v7 or earlier)
- Colour tables (RGB triplets for automated colour coding of maps)
BGS intends to supply additional add-on data for EU-Inspire compliance and emulation of other BGS Geology variants (e.g. replicating the web version of BGS Geology: 50k).
Add on datasets are supplied in ascii CSV format (comma-separated values). Most GIS software offers a function to ‘join’ data (or ‘relate’ data) onto a digital map. These add on datasets are designed to be joined by ‘attribute’, using a ‘primary key’. A primary key is simply a field within the datasets that identifies each record in a unique way. For BGS Geology: 50k we typically use the LEX_RCS field as our primary key. The images below outline the basic principle behind the data join:
Joining data for common GIS software is also described at the following resources:
The two add on packs provided with BGS Geology: 50k are called:
- Deprecated_data.csv and
- BGS_colours.csv
They are described below in Tables 8 and 9, and both can be joined to any theme/layer in BGS Geology: 50k that contains a LEX_RCS field.
| Data Field | Explanation of Data Field | Note |
| LEX_RCS | The primary key. This field is used to join the other field in this table onto the map data in BGS Geology: 50k | |
| BGSTYPE | The BGS Geology theme for which the added data is relevant: e.g. BEDROCK, SUPERFICIAL | |
| RCS_WEB | Direct hyperlink to the description of the lithology in the BGS Rock Classification Scheme accessible via the BGS website: e.g. www.bgs.ac.uk/bgsrcs/rcs_details.cfm?code=LMST | a |
| BED_EQ | Bed or equivalent. Lexicon code for the unit at bed or equivalent level where applicable | b |
| MB_EQ | Member or equivalent. Lexicon code for the unit at member or equivalent level where applicable | |
| FM_EQ | Formation or equivalent. Lexicon code for the unit at formation or equivalent level where applicable | |
| SUBGP_EQ | Subgroup or equivalent. Lexicon code for the unit at subgroup or equivalent level where applicable | |
| GP_EQ | Group or equivalent. Lexicon code for the unit at group or equivalent level where applicable | |
| SUPGP_EQ | Supergroup or equivalent. Lexicon code for the unit at supergroup or equivalent level where applicable | |
| MAX_INDEX | Maximum index. A number representing the maximum age (earliest or oldest time) of the unit: MAX_TIME_D field. Used for GIS querying and legend building: e.g. 13222120 | c |
| MIN_INDEX | Minimum index. A number representing the minimum age (latest or youngest time) of the unit: MIN_TIME_D field. Used for GIS querying and legend building: e.g. 13213140 | |
| MIN_AGE | Minimum age. Name of the age of minimum geochronological time applicable: e.g. ALPORTIAN | d |
| MIN_EPOCH | Minimum epoch. Name of the epoch of minimum geochronological time applicable: e.g. NAMURIAN | |
| MIN_SUBPER | Minimum sub-period. Name of the sub-period of minimum geochronological time applicable: e.g. PENNSYLVANIAN | |
| MIN_PERIOD | Minimum period. Name of the period of minimum geochronological time applicable: e.g. PERMIAN | |
| MIN_ERA | Minimum era. Name of the era of minimum geochronological time applicable: e.g. MESOZOIC | |
| MIN_EON | Minimum eon. Name of the eon of minimum geochronological time applicable: e.g. PHANEROZOIC | |
| PREV_NAME | Previous name(s) for the unit as listed in the BGS Lexicon of Named Rock Units | b |
| BGSREF_LEX | Alternative BGS reference colour at the Lexicon code level, LEX, as defined above: e.g. 626 (where no alternative needed as no clashes same colour used as above) | e |
| BGSREF_FM | Alternative BGS reference colour at the formation level, FM_EQ, as defined above: e.g. 266 for Sidmouth Mudstone Formation which includes Radcliffe Member | |
| BGSREF_GP | Alternative BGS reference colour at the group level, GP_EQ, as defined above: e.g. 505 for Mercia Mudstone Group which includes Sidmouth Mudstone Formation | |
| BGSREF_RK | Alternative BGS reference colour for the lithology RCS code, as defined above: e.g. 365 for mudstone and sandstone lithology of Radcliffe Member | |
| Note a: The RCS code is a multi-use code (single, composite and concatenated codes), unfortunately the web link is only able to interpret the single-code variant and can fail when used against the other types. BGS has decided to drop the use of the RCS hotlink in favour of the manual search available: www.bgs.ac.uk/bgsrcs/home.html Note b: BGS Geology: 50k V8 provides the ‘descriptions’ to these lithostratigraphic ‘codes’ and previous names. User feedback has indicated that the codes are infrequently used (compared with the description). These codes are all readily available (and maintained as a live, updated service) via the LEX_WEB hyperlink. The web link is a preferred mechanism for finding ‘previous names’ because the changes in UK stratigraphy names/concepts can be locally complex, requiring the wider resources available online. Note c: The Indexing fields are a mechanism to assist in developing semi stratigraphically sorted map legends. This facility is already provided by the LEX_RCS_I field. Note d: The geochronological names for each record are provided by the LEX_WEB hyperlink. Note: The BGSREF colouration system is being phased out and replaced with RGB triplets (see colour ‘add on’ file). User feedback indicates that these variants are infrequently used. | ||
| Data Field | Explanation of Data Field |
| LEX_RCS | The primary key. This field is used to join the other field in this table onto the map data in BGS Geology: 50k |
| BGSRED | RGB triplet (red) colour code used to define the foreground colour of the object (0–255) |
| BGSGREEN | RGB triplet (green) colour code used to define the foreground colour of the object (0–255) |
| BGSBLUE | RGB triplet (blue) colour code used to define the foreground colour of the object (0–255) |
| BGSRGB | RGB integer colour code used to define the foreground colour of the object (0–16777215) |