The Parent Material Database: A User Guide
Contents
1. British Geological Survey NATURAL ENVIRONMENT RESEARCH COUNCIL The Soil Parent Material Database SPM v4 A User Guide Landuse and Development Programme and Information Products Open Report OR 08 034 BRITISH GEOLOGICAL SURVEY LANDUSE AND DEVELOPMENT PROGRAMME AND INFORMATION PRODUCTS OPEN REPORT OR 08 034 The soil parent material database A User Guide The National Grid and other Ordnance Survey data are used with the permission of the Controller of Her Majesty s Stationery Office Licence No 100017897 2009 R Lawley Keywords Soil parent material Regolith Editor Contributors database B Rawlins A Tye G Wildman National Grid Reference SW corner 0 0 Centre point 0 0 NE corner 700000 0 Map Sheet na 1 50 000 scale National Soil parent material Front cover Cover picture details National Soil parent material Map Bibliographical reference RUSSELL LAWLEY 2009 The Soil parent material database A User Guide British Geological Survey Internal Report OR 08 034 45pp Copyright in materials derived from the British Geological Survey s work is owned by the Natural Environment Research Council NERC and or the authority that commissioned the work You may not copy or adapt this publication without first obtaining permission Contact the BGS Intellectual Property Rights Section British Geological Survey Keyworth e mail ipr bgs ac uk You may quote extracts of a2. Moderately Weak 5 0 12 5 MWEA Weak 1 25 5 0 WEAK 0 60 1 25 gt 60 hard soil Very Stiff 0 30 0 60 30 60 VSTI 3 Stiff 0 15 0 30 15 to 30 STIF 3 Firm 0 08 0 15 8 to 15 FIRM Soft 0 04 0 08 4to8 SOFT Very soft lt 0 04 lt 4 VSOF 37 2P STRCTR_FRS PM_DIC_STRUCTURE BEDDED STRUCTURE DEFINITION Host exhibits bedding features 1 BEDDED MASSIVE Host exhibits weak or discontinuous bedding or is locally structureless CLEAVED FOLIATED BEDDED host exhibits foliation and bedding features with cleavage CLEAVED LAMINATED BEDDED COMPLEX FIBROUS BEDDED Host exhibits lamination and bedding features with cleavage Reserved for host where chemical mineral growth deformation within host forms complex physical structure Host normally peat forms beds of fibrous material FOLIATED BEDDED FRACTURED JOINTED BEDDED Host exhibits foliation and bedding features typically reflecting a layered metamorphosed sequence Dominant rock structure comprises fracture surfaces subordinate structural features may also occur Host exhibits bedding features 1cm and jointing JOINTED_BEDDED_MASSIVE Host exhibits jointing of a weak discontinuous bedding or locally massive unit JOINTED_CLEAVED_FOLIATED Host exhibits jointing and or cleavage in a dominantly foliated unit JOINTED CLEAVED FOLIATED BEDDED Host exhibits jointing and or cleav
3. 60 SUBORDINATE CaCO3 40 LIMESTONE CLAY DOMINANT 60 SUBORDINATE CLAY 40 ORGANIC DOMINANT ORGANIC MATERIAL 90 P DOLOMITE SILICA CLAY DOMINANT MgCaCO3 60 SUBORDINATE SILICA CLA Y 40 Q sILICA CLAY DOMINANT SILICA 60 SUBORDINATE CLAY 40 R SILICA IDOMINANT CLAYS 60 SUBORDINATE SILICA 40 S SILICA DOMINANT SILICA 90 T LIMESTONE SILICA CLAY DOMINANT 60 SUBORDINATE SILICA CLAY 40 U ULTRABASIC IGNEOUS ROCKS WITH VERY LOW SILICA 45 V SILICA CLAY LIMESTONE DOMINANT SILICA CLAY 60 SUBORDINATE 63003 40 W SILICA CLAY_DOLOMITE DOMINANT SILICA CLAY 60 SUBORDINATE MgCaCO3 40 X MIXED BULK MINERALOGY IS VARIABLE DUE TO LITHOLOGY Z IPHOSPHATE_SILICA CLAY DOMINANT PO4 60 SUBORDINATE SILICA CLAY 40 32 2K MNR_MNRL CODE DEFINITION c CaCO3 f FERROAN CEMENTS Fe Ca MgCO3 p PHOSHATIC CEMENT MINERAL GYPSIFEROUS CEMENT MINERAL IHALITE CEMENT MINERAL ORGANIC MATERIAL IGLAUCONITIC CEMENT MINERAL DOLOMITE CEMENT CaMgCO3 33 2L CACO3_RANK PM_DIC_CACO3_CONTENT _ DEFINITION HIGH 50 CaCO3 LOW lt 10 CaCO3 MOD 10 gt 50 NA NOT APPLICABLE NONE NONE UNKNOWN VARIABLE VARIABLE HETEROGENOUS DISTRIBUTION OF CaCO3 34 2M CAC
4. 1 The structure of the 4 character PM classification codes used by the BGS The combination of origin mineralogy and grain size will broadly define the key parent material characteristics of any unit and thus its overlying soil character Further classification of parent material properties can be made by addition of additional codes from the other 52 fields held in the database Typically the codes relating to age hardness engineering strength and minor mineralogy are useful in this respect allowing the user to create flexible alternative classification systems to describe their parent materials 1 4 1 1 PM_CODE The first and most important data field describes the primary PM_CODE of the unit This primary PM code represents the MOST LIKELY parent material type for that map polygon i e the most likely parent material to be encountered at that location if the overlying soil was to be removed In geological terms it is the uppermost geological layer of material All the descriptions detailed in Fields 6 50 relate to this primary PM code and its associated description of the geological unit present at surface known as the LEX_ROCK code see below 1 4 1 2 A_PM_CODE Near surface geology can be locally complex an Alternative parent material code A_PM_CODE is provided for each map polygon to enable users to create variant models of soil types and to incorporate a degree of control over thin units near the land surface The
5. 4 1 5 IS_SPRFCL This field indicates whether the parent material for the map unit is derived from superficial deposits T or bedrock F In the UK superficial deposits are the product of recent glacial fluvial or aeolian activity and typically comprise unconsolidated materials 1 4 1 6 OVR BDROCK This field indicates whether the map unit is a superficial unit directly overlying bedrock T or a series of layered superficial units near surface F In the UK it is common for superficial units to be layered deposits and several layers of material may exist between ground level and the bedrock at depth Soils are typically developed from the topmost parent material with subordinate influence from underlying geological units This field may help users identify soil types indirectly influenced by underlying layers of superficial or bedrock units not just the uppermost unit 1 4 1 7 IS_VENEER This field indicates whether the map unit is likely to be of a type that forms a thin veneer generally less than 1m thick of material over the land surface True or of a type that locally thickens to a substantial body of material False This field may help users identify soil types over a parent material that may be thin and therefore subject to influence from the properties of the underlying associated parent material or subject to ploughing through during tillage This field is a synthesis of many field observations and gener
6. This field provides classification of the minimum engineering strength of a map unit See appendix 20 for dictionary 1 4 5 4 STRCTR FRS This field provides a simple description of the structure of the parent material classifying the unit by its jointing lamination or bedding in its freshest least weathered state See appendix 2p for dictionary 1 4 5 5 STRCTR_WTH The field provides a simple description of the structure of the parent material providing an indication of the distribution of fine material versus coarse material in its weathered state The structure of a parent material weathered or otherwise influences its drainage and weathering characteristics as well as the drainage and fabric of the overlying soils See appendix 2q for dictionary 12 1 4 6 Parent material database Colour Two classified colour values are provided parent material can impart a colour on overlying soils 1 4 6 1 COLOR FRSH This field is a free format description of parent material colour in its freshest least weathered state 1 4 6 2 COLOR WTH This field is a free format description of parent material colour from samples that are considered to be in its weathered state 1 4 7 Parent material database Variability A classification is provided to help the user assess the variability of a parent material The spatial variability of a parent material will affect the likely soil characteristics that are derived from it As a general rule
7. limestone 2111 hard limestone soft rocks rocks 2112 limestone marly chemically 2113 limestone chalky precipitated 2114 limestone detritial evaporated or 2115 limestone of organogenic 2116 carbonaceous or biogenic limestone origin 2117 lacustrine or freshwater limestone 2118 travertine calcareous sinter 2119 cavernous limestone 212 dolomite 2121 cavernous dolomite 2122 calcareous dolomite 18 213 marlstone 214 marl 2141 chalk marl 215 chalk 2142 gypsiferous marl 220 evaporites 221 gypsum 222 anhydrite 223 halite 230 siliceous rocks 231 chert hornstone flint 232 diatomite radiolarite 300 Igneous rocks 310 acid to 311 granite 3131 quartz diorite gabbro intermediate 312 granodiorite 3132 diorite plutonic rocks 3 diorite syenite 314 320 basic plutonic 321 gabbro rocks 330 ultrabasic 331 peridotite plutonic rocks 2 pyroxenite 340 acid to 341 rhyolite dacite 3411 obsidian quartz intermediate 342 3412 porphyrite volcanic rocks 343 andesite 3431 porphyrite interm 344 phonolite 3441 tephritic phonolite 345 trachyte 350 basic to 351 basalt ultrabasic volcanic rocks 2 diabase 353 pikrite 360 dike rocks 361 aplite 362 pegmatite 363 lamprophyre 370 pyroclastic 371 tuff tuffstone 1 agglomoratic tuff rocks tephra 3712 block tuff 3713 lapilli tuff 372 tuffite 3721 sandy tuffite volcanic 3722 silty tuffite 373 scoria 3723 clayey tuf
8. minor volumetrically mineral constituents For example soils derived from carbonate rich parent materials generally have an alkaline chemistry some parent materials create distinctive soils rich in glauconite or natural phosphate The soil parent material database has a series of classifications as well as specific data for classifying likely mineral content Drainage of soils is affected by parent material type in two ways Firstly the texture of the parent material type contributes to the soil texture and thus porosity and permeability of the soil itself Secondly the drainage characteristics of the parent material controls the drainage characteristics of the overlying soil by limiting or enhance through flow or sub soil run off For example consider a soil developing over a sandstone If the sandstone is porous and permeable it will be freely draining and the overlying soil is 16 likely to be sandy and free draining even possibly prone to drying out However if the underlying sandstone is well cemented it may be poorly draining causing the overlying soil to become seasonally waterlogged gleyed or possibly peaty Other factors such as slope play a role here hence the importance of combining the parent material database with other national databases for the environment The soil parent material database provides a spatial framework and attribution to allow environmental scientists classify soil characteristics in bespoke digital soil
9. parent material type and comprises subdivisions of the Igneous Metamorphic Sedimentary classifications e g Sedimentary Clastic Sedimentary_carbonate See appendix 2d for dictionary 1 4 2 4 SUBROOT_LITHOLOGY This is the next simplest level of lithological attribution for each parent material type and comprises a semi textural subclassification of the PM type e g Sedimentary_Carbonate_Limestone_argillic This field is created by combining ROOT PM with DOM MNRL and GEN GRAIN fields 1 4 2 5 GENESIS This field provides a description of how the parent material was formed e g Igneous intrusion See appendix 2e for dictionary 1 4 2 6 GEN_PMLITH This is a simplified geological description of the parent material and is derived from the original DiGMapGB 50 database In general the aim is to provide the user with as simplified a lithological description as possible 1 4 2 7 LEX_ROCK This field is the standard DiGMapGB 50 code that describes the geological units found in Great Britain It provides the starting point for the parent material characterisation It comprises a stratigraphic code LEX and Lithology code ROCK 1 4 2 8 SYSTEM This field is the standard DiGMapGB 50 stratigraphic SYSTEM classification for the parent material denoting its geochronological age e g Triassic Jurassic 1 4 2 9 STAGE This field is the standard DiGMapGB 50 stratigraphic STAGE classification for the parent materi
10. soil characteristics can naturally vary for any given parent type due to a range of environmental factors such as rainfall or land use If the parent material characteristics vary widely then the resulting overlying soils will also have a very broad range of characteristics 1471 VARIABILITY This field provides a simple classification of high medium and low Low indicates that the parent is spatially uniform across a wide area uniform over 100 s metres medium indicates variability at a local scale uniformity at 10 s of metres whilst high variability suggests that the unit may vary at a metre scale For example some Jurassic rock sequences comprise weak mudstone with sporadic interbeds of hard limestone The beds of limestone can often be only 20cm thick and range 1m to 20m apart so overlying soils can be dominated by a layer of limestone or a layer of mudstone depending upon how the soil has formed and the relative position of the rock layers in the landscape The layering occurs at a scale we can estimate to be locally highly variable See appendix 2r for dictionary 1 4 8 Parent material database Code only versions of data The following fields are code only versions of fields provided elsewhere in a verbose form These fields are of use to GIS users who wish to create simple multi field reclassifications of the database without building overly complex text legends 1 4 8 1 ORIGIN PM This field is a coded version of the ORIGIN
11. 03 FORM PM DIC CACO3 FORM CACO3 FORM DEFINITION BED Unit contains beds of calcareous material limestone lime sandstone or similar CEMENT Carbonate present as an intergranular cement CEMENT CLASTS Carbonate present as an intergranular cement and as detrital clasts CLASTS Carbonate present as detrital clasts of calcareous material DETRITAL Carbonate present as detrital material derived from underlying unit altern8 pmm ranking HOST Whole Unit is calcareous e g chalk MATRIX Unit comprises an argillic matrix comprised of calcareous material MINERAL Carbonate present as crystals or veins of calcareous material within the host NA Not Applicable NODULE Carbonate present as nodules calcrete within the host UNKN 35 2N HARDNESS PM_DIC_HARDNESS CODE DEFINITION VHARD IBREAKS ONLY WITH HAMMER FRACTURES ACROSS GRAINS INDURATED VARIABLE 5 VARYING HARDNESS DUE TO LITHOLOGICAL VARIABILITY VSOFT GRAINS FALL APART WITH SLIGHT PRESSURE BY HAND SOFT IMODERATELY EASY TO BREAK OFF CHIPS BY HAND PENKNIFE HARD INEED HAMMER TO BREAK ROCK FRACTURES AROUND GRAINS UNKN UNKNOWN 36 20 STRNGTH_MN AND STRNGTH_MX T Uniaxial Compressive Strength erm Strength MPa blows 300mm Code penetration Extremely Strong gt 200 ESTR Very Strong 100 200 VSTR Strong 50 100 STRO 8 Moderately Strong 12 5 50 MSTR 7
12. A PM CODE can be used when the primary parent material is likely to be a thin veneer of material typically less than 1m thick overlying a notably different rock type For example a thin layer of Peat PM_code UOOP overlying a Glacial Till deposit will have the A PM CODE of the Till unit PM CODE UGRX Soils in this area could be derived from a combination of the two parent materials because they are related by their close vertical proximity 1 4 1 3 B PM CODE Similarly the B PM CODE details the parent material code of any underlying Bedrock units This code can be used when the map unit is derived from a superficial deposit that is less than 5m thick ie locally thin enough to be subject to influence from the characteristics of the underlying bedrock The user can assess the thinness of the superficial deposits by referring to the IS VENEER field see below 1 4 1 4 ESB_CODE The ESB Code field provides the most applicable European Soil Bureau parent material code for the map unit The ESB code is defined in the Georeferenced Soil database for Europe Finke et al 2001 and is summarised in Appendix 2 Codes with an imprecise correlation are marked with a suffix x Multi lithic parent material e g layered units are represented by two or more codes separated by _ The ESB Code is useful for users considering integration of this database into European soil geology databases See appendix 2a for its dictionary 1
13. AT na DUMMY CODE GRAVEL 2 0 60 B BOULDER 600 A ARGILLACEOUS lt 0 06 N ARENACEOUS 0 06 2 0 R RUDACEOUS 2 0 0 ARGILLIC ARENACEOUS lt 2 0 T ARENACEOUS RUDACEOUS 0 06 X MIXED ARGILLIC RUDACEOUS ALL L COBBLE 60 600 D CLAY lt 0 002 27 2H SOIL_TEXT AND SOIL_GROUP PM classification of soil sample textures and associated Defra classification of soil textures based upon the NSRI UK Soil texture triangle Hodgson 1997 Images show the regions of texture triangle represented by the description See Appendix 3 for enlarged ternary diagram The use of the prefix e denotes that the database object has no specific texture data available and so its soil texture has been estimated from similar parent material types Eg a soil texture code of eS_SL denotes that the parent material type has no observed data but is of a type similar to other parent material that are coded as S_SL Sand to Sandy Loam OBSERVED SOI OBSERVED SOIL TEXTURE DESCRIPTION APPROXIMATE Defra TEXTURE L TEXTURE CLASS TRIANGLE ALL ALL ALL C CLAY HEAVY SOILS CL CLAY AND LOAM SOILS ALL TYPES EXCEPT HEAVY MEDIUM AND SANDY LIGHT SILTY SOILS MCL CLAY CLAYEY LOAM AND SILTY CLAY HEAVY TO MEDIUM LOAM SILTY SOILS A C ML CLAY CLAYEY OR SILTY LOAM LIMITED HEAVY MEDIUM SAND IN THE LOAMS SILTY AND LIGHT SILTY SOILS CS CLAY SAND SAN
14. CH INSTITUTE UK Soil texture triangle Hodgson 1997 Cranfield University and for the Controller of HMSO 2008 100 Clay 100 Sand 90 10 100 Silt Texture class Texture name CLAY SC SANDY CLAY ZC SILTY CLAY SCL SANDY CLAY LOAM CL CLAY LOAM ZCL SILTY CLAY LOAM 5 SAND LS LOAM SAND SL SANDY LOAM SZL SANDY SILT LOAM ZL SILTY LOAM Some parent material types utilise combined codes to define their texture So a parent material expected to create soils ranging from Sandy Clay Loam to Sandy Loam is denoted by a derivative code of SXL covering SCL and SL 41 Glossary parent material geological deposits which immediately underlie the layers commonly known as topsoil and subsoil Lex_rock A code used within the BGS DiGMapGB 50 map database that denotes the stratigraphy lex and lithology rock of rocks and deposits across the UK References British Geological Survey holds most of the references listed below and copies may be obtained via the library service subject to copyright legislation contact libuser bgs ac uk for details The library catalogue is available at http geolib bgs ac uk Ault L amp Mackenzie A C 2006 From LIMS to geochemistry database GBASE samples analytical data British Geological Survey report IR 06 075 British Geological Survey 2006 National Superficial Thickness Model of Great Britain 1 50 000 scale DiGMapGB 50 d
15. DY LOAMS BUT HEAVY MEDIUM GENERALLY LESS THAN 40 SILT XCL CLAYEY AND SANDY SILTY CLAY LOAMS HEAVY TO MEDIUM SOILS CL CLAY LOAM MEDIUM SOILS y L LOAMY SOILS ALL TYPES MEDIUM TO LIGHT SILTY SOILS MCL CLAY LOAM TO SILTY CLAY LOAM MEDIUM SILTY SOILS ML CLAYEY TO SILTY LOAMS LIMITED SAND MEDIUM SILTY TO LIGHT SILTY SOILS 28 29 OBSERVED SOI OBSERVED SOIL TEXTURE DESCRIPTION APPROXIMATE Defra TEXTURE L_TEXTURE CLASS TRIANGLE 5 SANDY SOILS SAND AND SAND LIGHT SANDY SOILS dev SL SANDY AND LOAMY SOILS LIMITED CLAY MEDIUM TO LIGHT SOILS S SL SANDY TO SANDY LOAM SOIL LIGHT SANDY SOILS Am S SXL SANDY TO SANDY LOAM AND SANDY CLAY MEDIUM SANDY LOAM SOIL LIGHT SANDY SOILS S SXLL SANDY TO CLAYEY AND SILTY LOAM SOIL MEDIUM TO LIGHT LIMITED CLAY MODERATE HIGH SAND SOILS S_XZL SANDY AND SANDY SILTY LOAMS LITTLE LIGHT SOILS CLAY SC SANDY CLAY HEAVY SANDY SOILS A SCL SANDY CLAY LOAM MEDIUM SANDY SOILS An SX SAND LIGHT SANDY SOIL SXL SANDY CLAY LOAM TO SANDY LOAM MEDIUM SANDY TO LIGHT SANDY SOILS SXL L SANDY CLAYEY AND SILTY LOAMS MEDIUM TO LIGHT MINIMUM 2096S AND SOILS SZL SANDY SILT LOAM LIGHT SILTY SOILS XC CLAYEY SOILS SANDY CLAY CLAY AND SILTY CLAY A XCL SANDY CLAY CLAY AND SILTY CLAY LOAM MEDIUM SOILS SANDY TO SILTY LOAM OBSERVED_SOI OBSERVED_SOIL_TEXTU
16. ES WITH SUBEQUAL ARENACOUS ED MATRIX GRAVEL SAND MUD MATRIX SUP FRAGMENTS STONES WITH SUBORDINATE ARGILLIC PORTED TO ARENACEOUS MATRIX MATRIX CLASTIC HETEROGENEOU HETEROGENOUS UNIT WITH VARYING ZONES OF MATRIC 5 CLASTIC DOMINANCE MUD_MATRIX PLASTIC SOFT PLASTIC ARGILLIC MATRIX NO ROCK STONE CONTENT MUD_MATRIX_WITH_GRAVEL DOMINANT ARGILLIC ARENACEOUS MATRIX WITH SUBORDINATE ROCK FRAGMENTS STONES ORGANIC_MATRIX DOMINANT ORGANIC MATRIX NO ROCK STONE CONTENT SAND MATRIX ARENACEOUS MATRIX NO ARGILLIC COMPONENT AND NO ROCK FRAGMENT OR STONE CONTENT SAND MATRIX WITH GRAVEL ARENACEOUS MATRIX NO ARGILLIC COMPONENT WITH A SUBORDINATE ROCK FRAGMENT OR STONE CONTENT SAND MUD MATRIX DOMINANT ARGILLIC ARENACEOUS MATRIX NO ROCK FRAGMENTS SAND MUD MATRIX WITH GRAVE DOMINANT ARGILLIC ARENACEOUS MATRIX SOME L ROCK STONE CONTENT SAND MUD MATRIX WITH REMNA DOMINANT ARGILLIC ARENACEOUS MATRIX WITH VERY NT GRAVEL SUBORDINATE AND DEGRADED ROCK FRAGMENTS STONES UNKN UNKNOWN 39 2R VARIABILITY PM_DIC_UNIT_VARIABILITY UNIT VARIABILITY DEFINITION HIGH UNIT IS HETEROLITHIC AT MAP OBJECT SCALE OR IS A COLLECTION OF DIFFERENT ROCK UNITS LOW IT IS HOMOGENOUS OBJECT SCALE MOD UNIT HAS HETEROGENEITY AT MAP OBJECT SCALE OR IS A COLLECTION OF SIMILAR ROCK UNITS UNKN 40 Appendix 3 Classification of soil texture NATIONAL SOIL RESEAR
17. House West Mains Road Edinburgh EH9 3LA Tel 0131 667 1000 Fax 0131 668 2683 email scotsales bgs ac uk Natural History Museum Cromwell Road London SW7 5BD Tel 020 7589 4090 Fax 020 7584 0 Tel 020 7942 5344 45 email bgslondon bgs ac uk Columbus House Greenmeadow Springs Tongwynlais Cardiff CF15 7NE Tel 029 2052 1962 Fax 029 2052 1963 Forde House Park Five Business Centre Harrier Way Sowton EX2 7HU Tel 01392 445271 Fax 01392 445371 Maclean Building Crowmarsh Gifford Wallingford OX10 8BB Tel 01491 838800 Fax 01491 692345 Geological Survey of Northern Ireland Colby House Stranmillis Court Belfast BT9 SBF Tel 028 9038 8462 Fax 028 9038 8461 www bgs ac uk gsni parent Body Natural Environment Research Council Polaris House North Star Avenue Swindon SN2 1EU Tel 01793 411500 Fax 01793 411501 www nerc ac uk Website www bgs ac uk Shop online at www geologyshop com Foreword This report is a user guide to the content and application of the National Soil Parent Material database produced by the British Geological Survey BGS The National Soil Parent Material database provides simplified descriptions of near surface geological materials their overlying soils Acknowledgements A large number of individuals in BGS have contributed to the project This assistance has been received at all stages of the study In addition to the collection of data many individuals have freely given their adv
18. L LACUSTRINE FLUVIAL LACUSTRINE MATERIAL OF PREVIOUS OR ANCIENT TRACT FLUVIAL MARINE MATERIAL CURRENT OR ANCIENT ALLUVIAL TRACT SED_GENERIC SEDIMENTARY GENESIS UNKNOWN GLACIGENIC LAIN GLACIOFLUVIAL GLACIAL OUTWASH GLACIOLACUSTRINE GLACIAL LACUSTRINE OR PONDED LACUSTRINE 6 MATERIAL OF CURRENT ANCIENT TRACT LACUSTRINE FLUVIAL LACUSTRINE MATERIAL OF CURRENT OR ANCIENT ALLUVIAL TRACT LAGOONAL MARINE TE MATERIAL OF CURRENT OR ANCIENT COASTLINE LITTORAL MARINE ER OR NEAR SHORE MARINE MATERIAL OF CURRENT OR ANCIENT COASTLINE MARINE OFFSHORE MARINE MATERIAL OF CURRENT OR ANCIENT COASTLINE MIRE OR BOG RAISED OR LOWLAND BOG PEDOGENIC PEDOGENIC PERIGLACIAL PERIGLACIAL PERIGLACIAL LOESSIC mA REWORKED LOESS REWORKED PRECIPITATION CHEMICAL PRECIPITATION PYROCLASTIC SEDIMENTARY REWORKED VOLCANOCLASTIC EJECTA WEATHERING IN SITU WEATHERING REGOLITH SAPROLITE UNKNOWN GENESIS NOT DETERMINED 25 2F MIN_GRAIN MAX_GRAIN DOM_GRAIN IDOMINANT GRAINSIZE Particle Diameter mm BOULDER GRAVEL SILT 10 002 0 06 MUD 0 0 06 CLAY 0 0 002 UNKN UNKNOWN Igneous rock crystal size 26 2G GRAIN GRAINSIZE CODE GRAINSIZE NAME Particle Diameter mm F FINE lt 0 25 M MEDIUM 0 25 gt 2 C COARSE 2 0 2 ISILT 0 002 0 06 S ISAND 0 06 2 0 P PE
19. PM field 1 4 8 2 ROOT PM This field is a coded version of the Root Lithology field 1 4 8 33 D MIN CODE This field is a coded version of the DOM MNRL field 1 4 84 G GRN CODE This field is a coded version of the GEN GRAIN field 1 4 8 5 STAGECODE This field is a coded version of the STAGE PLUS field 13 1 4 8 6 This field is coded version of the SYSTEM Field 1 4 9 Parent material database Alternative DiGMapGB 50 Lex rock descriptors The parent material database provides two alternative parent material codes for each object in the database These codes allow users to develop alternative soil models based on the thinness of near surface units 1 4 9 1 LEX ROCK Near surface geology can be locally complex alternative DiGMapGB 50 LEX ROCK codes provided for each map polygon to enable users to create variant models of geological deposits and to incorporate a degree of control over thin units near the land surface The A LEX ROCK code can be used when the LEX_ROCK code is likely to be a thin veneer of material overlying a notably different rock type For example a thin layer of Peat LEX ROCK code P_PEAT overlying a Glacial Till deposit will have the A LEX ROCK code of the Till unit TILMP DMTN The deposits are associated by their close proximity 1 4 9 2 B LEX ROCK Similarly the B LEX ROCK code details the DiGMapGB 50 Lex Rock code of any underlying Bedrock units W
20. RATE 2c ORIGIN_PM 2d ROOT_PM 2e GENESIS 2f MIN_GRAIN MAX_GRAIN DOM_GRAIN 2g GEN_GRAIN 15 15 16 18 18 22 23 24 25 26 27 2h SOIL TEXT AND SOIL GROUP 21 GRV_ABNDNC 2j DOM MNRL 2k MNR MNRL 21 CACO3 RANK 2m CAC03 FORM 2n HARDNESS 20 STRNGTH MN AND STRNGTH MX 2p STRCTR FRS 2g STRCTR WTH 2r VARIABILITY Appendix 3 Classification of soil texture GLOSSARY REFERENCES TABLES Table 1 General content of the PM database 28 31 32 33 34 35 36 37 38 39 40 41 42 42 1 Background The soil parent material PM database is part of a series of GIS maps designed to help environmental scientists and consultants assess the characteristics of the near surface weathered zone In particular the data focuses upon the material from which top soils and subsoils A and B horizons develop i e from the base of pedological soil down to c 3m 1 1 WHAT IS SOIL PARENT MATERIAL A soil parent material is a geological deposit over and within which a soil develops Typically the parent material is the first recognisably geological deposit encountered when excavating beneath the soil layer It represents the very near surface geology In general the geological deposits closer to the ground surface are the most weathered whilst the deeper deposits are less so The interface between soil and parent geology can vary from a sharp clearly defined boundary to a diffuse con
21. RE DESCRIPTION APPROXIMATE Defra TEXTURE 20 SAND SILTY SOILS L_TEXTURE CLASS TRIANGLE 6 SILTY CLAY HEAVY SILTY SOILS ZCL SILTY CLAY LOAM MEDIUM SOILS ZL SILT LOAM LIGHT SILTY SOILS Arm ZXL SILTY CLAY TO SILTY LOAM LESS THAN pus TO LIGHT x 30 21 GRV_ABNDNC PM_DIC_STONE CLAST_ABUNDANCE GRAVEL ABUNDANCE DEFINITION ABUNDANT lt 35 CLASTIC CONTENT IN HOST NA INO CLASTIC CONTENT IN HOST FEW COMMON 5 lt 35 CLASTIC CONTENT IN HOST UNKN UNKNOWN VARIABLE CLASTIC CONTENT VARIES IN HOST 31 21 DOM_MNRL D DOLOMITE BU LK min eral DOM mineralogy class DOMINANT MINERALOGY DEFINITION ogy UN KNOWN IBULK MINERALOGY IS UNKNOWN ACID IGNEOUS ROCKS WITH HIGH SILICA 63 B BASIC IGNEOUS ROCKS WITH LOW SILICA 45 5296 C CLAYS IDOMINANT CLAY MINERALS 90 DOMINANT CaMgCO3 with SOME CaCO3 E EVAPORITE IPREDOMINANTLY SULPHATES AND HALIDES F IRONSTONE DOMINANT Fe Ca MgCO3 with SOME CaCO3 G IRONSTONE SILICA CLAY DOMINANT Fe Ca MgCO3 60 SUBORDINATE SILICA CLAY 40 H SILICA CLAY_IRONSTONE DOMINANT SILICA CLAY 60 SUBORDINATE Fe Ca MgCO3 40 I INTERMEDIATE IGNEOUS ROCKS WITH MOD SILICA 52 63 CHALK DOMINANT CaCO3 90 L LIMESTONE DOMINANT with SOME CaMgCO3 M LIMESTONE IDOMINANT CLAYS
22. SEDIMENTARY CLASTIC AND CALCAREOUS TIC ROCKS ML SED CARBONATE IMETAMORPHOSED SEDIMENTARY CALCAREOUS ROCKS MP SED PRECIPITATE IMETAMORPHOSED SEDIMENTARY PRECIPITATE ROCKS MT TECTONIC IMETAMORPHOSED ROCKS WITH A STRONG TECTONIC FABRIC MV META IGN VOLCANOCLASTIC IMETAMORPHOSED VOLCANOCLASTIC IGNEOUS ROCKS M M V META SED VOLCANOCLASTIC IMETAMORPHOSED VOLCANOCLASTIC SEDIMENTARY ROCKS X META MIXED IMETAMORPHOSED ROCKS MIXED IG SED ORIGIN SC SED CLASTIC ILITHIFIED SEDIMENTARY CLASTIC ROCK SK CARBONATE CLASTIC ILITHIFIED SEDIMENTARY CLASTIC AND CALCAREOUS ROCKS SL SED CARBONATE ILITHIFIED SEDIMENTARY CALCAREOUS ROCKS SO SED ORGANIC ILITHIFIED SEDIMENTARY ORGANIC ROCKS COALS SP SED PRECIPITATE ILITHIFIED SEDIMENTARY PRECIPITATE ROCKS SV SED VOLCANOCLASTIC LITHIFIED SEDIMENTARY VOLCANOCLASTIC ROCKS SX SED MIXED ILITHIFIED SEDIMENTARY ROCKS MIXED ORIGIN UA UNCONSOLIDATED AEOLIAN UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK AEOLIAN UC UNCONSOLIDATED FLUVIAL UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK FLUVIAL UF UNCONSOLIDATED GLACIOFL UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK GLACIO UVIAL FLUVIAL UG UNCONSOLIDATED GLACIGENI SOLIDATED SEDIMENTARY CLASTIC ROCK ICE LAIN UL UNCONSOLIDATED_GLACIOLA UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK GLACIO CUSTRINE LACUSTRINE UM UNCONSOLIDATED MARINE UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK MARINE E
23. STUARINE UO UNCONSOLIDATED ORGANIC UNCONSOLIDATED SEDIMENTARY ORGANIC ROCKS ACCUMULATION OF ORGANICS UR UNCONSOLIDATED RESIDUAL UNCONSOLIDATED SEDIMENTARY CLASTIC ROCK RESIDUAL UX JUNCONSOLIDATED CLASTIC UNCONSOLIDATED SEDIMENTARY ROCKS MIXED ORIGIN XX UNKNOWN UNKNOWN XX MIXED LITHOLOGIES MIXED 24 2e GENESIS GENESIS ARTIFICIAL DEPOSITS LAIDDOWN OR DISTURBED BY HUMANS IEXTRUSIVE EXTRUDED IGNEOUS ROCK INTRUSIVE INTRUDED IGNEOUS ROCK MINERALISATION IMINERALISATION BY FLUID OR CONTACT METAMORPHISM VOLCANOCLASTIC IVOLCANOCLASTIC EJECTA MET GENERIC REGIONAL CONTACT METAMORPHISM MET EXTRUSIVE IMETAMORPHOSED EXTRUDED IGNEOUS ROCK MET INTRUSIVE IMETAMORPHOSED INTRUDED IGNEOUS ROCK MET VOLCANOCLASTIC IMETAMORPHOSED VOLCANOCLASTIC EJECTA MET SED IREGIONAL CONTACT METAMORPHISM MULTIPLE IMIXED METHODS OF GENESIS AEOLIAN WIND BLOWN AEOLIAN LOESSIC WIND BLOWN LOESS NOT DUNE ALLUVIAL FLUVIAL MATERIAL OF CURRENT OR RECENT ALLUVIAL TRACT ALLUVIAL FAN FLUVIAL FAN MATERIAL OF CURRENT OR RECENT ALLUVIAL TRACT ALLUVIAL LOESSIC wer WIND BLOWN LOESS NOT DUNE REWORKED ALLUVIAL TERRACE H TERRACE MATERIAL OF CURRENT OR RECENT ALLUVIAL FLUVIAL FLUVIAL MATERIAL OF PREVIOUS OR ANCIENT ALLUVIAL TRACT FLUVIAL DELTAIC m S MATERIAL OF PREVIOUS OR ANCIENT ALLUVIAL FLUVIA
24. age in a foliated and bedded unit JOINTED CLEAVED FOLIATED MASSIVE Host exhibits jointing and or cleavage of a weakly discontinuously foliated or locally massive unit JOINTED_CLEAVED_LAMINATED_BEDDED JOINTED_FOLIATED Host exhibits jointing and or cleavage in a laminated and bedded unit Host exhibits jointing of a dominantly foliated unit JOINTED FOLIATED BEDDED Host exhibits lamination and bedding features with jointing JOINTED FOLIATED MASSIVE Host exhibits jointing of a weakly discontinuously foliated or locally massive unit JOINTED LAMINATED JOINTED_LAMINATED_BEDDED Host exhibits dominant lamination features with jointing Host exhibits lamination and bedding features with jointing JOINTED_MASSIVE LAMINATED Host exhibits jointing of an otherwise massive unit Host exhibits lamination features LAMINATED_BEDDED Host exhibits lamination and bedding features typically reflecting a layered argillic arenaceous sequence LAMINATED_MASSIVE UNKN Host exhibits a weak or discontinuous lamination or is locally massive structure in unknow or lex rock unit too diverse 38 20 STRCTR_WTH PM_DIC_WEATHERED_STRUCTURE CODE DEFINITION GRAVEL CLAST SUPPORTED DISAGGREGATED GRAVEL 2 0 600MM IN DIAMETER LITTLE INTERGRANULAR MATRIX GRAVEL CLAY MATRIX SUPPORT ROCK FRAGMENTS STONES WITH SUBORDINATE ARGILLIC ED MATRIX GRAVEL SAND MATRIX SUPPORT ROCK FRAGMENTS STON
25. al denoting its geochronological age e g Toarcian Bajocian Nb The age of the parent material has no direct influence on the soil type however it has been noted that material from certain geological eras possess soil forming characteristics that are difficult to explicitly define For example Triassic Mudstones weather in slightly different ways to Jurassic Mudstones So even if there are no explicit characteristics we can extract from the parent material data the age fields can provide users with an additional factor by which to group or subdivide the parent material types 1 4 2 10MULTILITHIC This field indicates if the parent material comprises two or more distinct lithologies For example a unit described as sandstone with interbedded mudstone IS a multilithic unit Y This indicates that the overlying soils may vary significantly within the map polygon as they are derived from more than one possible parent 1 4 3 Parent material database Texture descriptions Texture is described in eight data fields by a series of dictionaries These dictionaries are described as follows 1 4 3 1 MIN GRAIN This is a qualitative classification of the smallest grain size to be expected from the parent material The terms used are clay silt mud generic for clay or silt sand gravel and boulder for sedimentary and metasedimentary rocks Fine medium and coarse for igneous and meta igneous rocks The value is a estimation derived from
26. al theory of sedimentology Typically deposits such as Peat and loess will form a veneer or blanket like deposit over the land surface whereas alluvial or glacially derived deposits may form deep irregular shaped channels hollows or hills 1 4 1 8 PMMID This field is a unique integer to identify individual polygons 1 4 2 Parent material database Lithological descriptions Map unit lithology is described in nine data fields by a series of hierarchical dictionaries These dictionaries are described as follows 1 4 2 1 SUBSTRATE This field defines whether the parent material is derived from Bedrock or Superficial deposits There is an additional classification of Surficial deposits denoting superficial units that have a thin blanket like morphology veneer This category of unit is important as soils form on the uppermost layers of geology and so any thin laterally impersistent unit can have a significant effect on soil type The accumulated materials layer should also be used in conjunction with parent materials of this type Soils developed from bedrock units are classed as lithoskeletal soils See appendix 2b for dictionary 14 2 2 ORIGIN PM This is the simplest descriptive term for each parent material type and comprises Igneous Metamorphic and Sedimentary classifications 1 the PM has a sedimentary origin See appendix 2 for dictionary 1 4 2 3 ROOT PM This is the next simplest descriptive term for each
27. ata CD Rom Version 4 16 Keyworth Nottingham British Geological Survey British Geological Survey 2007 Digital Geological Map of Great Britain 1 50 000 scale DiGMapGB 50 data CD Rom Version 4 16 Keyworth Nottingham British Geological Survey FINKE P ET AL 2001 GEOREFERENCED SOIL DATABASE FOR EUROPE MANUAL OF PROCEDURES VERSION 1 1 Gillespie M amp Styles M 1999 BGS rock classification scheme Volume 1 Classification of igneous rocks 2nd ed British Geological Survey Research Report RR 99 006 M R Gillespie amp M T Styles 2nd ed Hallsworth C amp Knox R W O B 1999 BGS rock classification scheme Volume 3 classification of sediments and sedimentary rocks British Geological Survey Research Report RR 99 003 Jenny H 1941 Factors of Soil Formation a System of Quantitative Pedology McGraw Hill New York 281pp McMillan A amp Powell J H 1999 BGS rock classification scheme Volume 4 classification of artificial man made ground and natural superficial deposits applications to geological maps and databases in the UK British Geological Survey Research Report RR 99 004 Robertson S 1999 BGS rock classification scheme Volume 2 classification of metamorphic rocks British Geological Survey Research Report RR 99 002 Hodgson J M 1997 Soil Survey field Handbook Soil Survey Technical Monograph No 5 Silsoe Defra 2006 Cross Compliance Guidance for Soil Management Departmen
28. ataset is derived from numerous geological maps geochemical datasets and archives of textual material It is a spatial dataset designed to be used at a working scale of 1 50 000 Most geological maps were originally fitted to a particular topographic base and care must be taken in interpretation for example when the geological data are draped over a more recent topography All spatial searches against the data should be done with a minimum 50 m buffer Parent material maps being derived from qualitative geological maps are by their nature also subject to a degree of interpretation 1 6 DATA HISTORY This is the first published version of the Soil Parent Material Dataset It was first released spring 2009 2 Contact information For all data and licensing enquiries please contact Central Enquiries British Geological Survey Kingsley Dunham Centre Keyworth Nottingham NGI2 5GG Direct tel 44 0 115 936 3143 Fax 44 0 115 9363150 Email enquiries Obgs ac uk 15 Appendix 1 A brief overview of the relationship between Soils and parent materials Soil formation is governed by a number of environmental parameters These parameters were first identified in what is known as Jenny s equation Jenny 1941 or model of soil forming factors f CLO R P T Where Cl Climate precipitation O Organic matter Vegetation cover Land use R Relief elevation position in landscape P parent material T Time Moder
29. avel plain sand or 5321 flood plain sand gravel 5322 flood plain gravel 540 fluvial clays 541 river clayand 5411 terrace clay and silt silts and loams silt 5412 terrace loam 5413 floodplain clay and silt 542 river loam 543 overbank 5431 floodplain clay and deposits silt 5432 floodplain loam 550 lake deposits 551 lake sand and delta sand 552 lake marl bog lime 553 lake silt 560 residual and 561 residualloam 5611 stony loam redeposited 5612 clayey loam loams from silicate 562 redeposited 5621 running ground loam rocks 570 residual and 571 residual clay 5711 clay with flints redeposited 5712 ferruginous residual clays from clay calcareous rocks 5713 calcareous clay 5714 non calcareous clay 20 5715 marly clay 572 redeposited 5721 stony clay clay 580 slope deposits 581 slope wash alluvium 582 colluvial deposits 583 talus scree 5831 stratified slope deposit 600 Unconsolidated 610 morainic 611 glacial till 6111 boulder clay glacial deposits deposits glacial drift 612 glacial debris 620 glaciofluvial 621 outwash sand deposits glacial sand 622 outwash gravel glacial gravel 630 glaciolacustrin 631 varves deposits 700 Eolian deposits 710 loess 711 loamy loess 712 sandy loess 720 eolian sands 721 dune sand 722 cover sand 800 Organic 810 peat mires 811 rainwater fed 8111 folic peat materials moor peat 8112 fibric peat raised bog 8113 te
30. fite volcanic 374 breccia 375 volcanic ash 376 ignimbrite pumice 400 Metamorphic 410 weakly 411 meta shale 1 graphitic slate rocks metamorphic 412 argillite slate rocks 420 acid regional 421 meta 4211 quartzite schist metamorphic 422 quartzite rocks 423 phyllite mica schist 424 gneiss 425 granulite 426 sensu stricto migmatite 430 basic regional 431 greenschist 4311 prasinite chlorite metamorphic 4312 schist talc schist rocks 4313 19 432 amphibolite 433 eclogite 440 ultrabasic 441 serpentinite 4411 greenstone regional metamorphic rocks 450 calcareous 451 marble regional 452 calcschist metamorphic skarn rocks 460 rocks formed 461 contact slate 4611 nodular slate by contact 462 hornfels metamorphism 463 calcsilicate rocks 470 tectogenetic 471 tectonic metamorphic 472 breccia rocks or 473 cataclasite cataclastic mylonite metamorphism 500 Unconsolidated 510 marine and 511 5111 Tertiary sand deposits estuarine sands 512 Quaternary 5121 Holocene coastal alluvium sand 5122 sand with shells weathering Quaternary delta sand residuum and sand slope deposits 520 marine and 521 pre 5211 Tertiary clay estuarine clays 522 Quaternary 5212 Tertiary silt and silts clay and silt 5221 Holocene clay Quaternary 5222 Holocene silt clay and silt 530 fluvial sands 531 river terrace 5311 river terrace sand and sand gravels 532 or gravel flood 5312 river terrace gr
31. from the BGS GBASE IMAU and GTECH databases and particle size distributions are derived by laser granulometry wet and dry sieving and sedimentation techniques The soil parents are classified by the dominant texture indicated by the samples when plotted on a ternary diagram Some soil parent material types have no or few sample measurements These soil parent types are provided with an estimated classification based upon the principle of textural similarity between parents of similar origins and texture See appendix 2h for dictionary 1 4 3 6 SOIL_GROUP This field provides a general description of the observed soil texture in terms of Heavy Medium or Light soils as broadly defined in the Defra Cross Compliance Guidance for Soil Management Defra 2006 See appendix 2h for dictionary Additionally The parent material database stores information about gravel stone pebble content The presence of gravel can have a dramatic effect on soil characteristics particularly drainage and water storage 1 4 3 7 GRV_CONTNT This field is a logical flag Y N to indicate that the parent material may contain gravel stones or is capable of weathering into a soil that will contain gravel e g a bed of quartzite will decompose into a soil that contains fragments of quartzite where as a glaciolacustrine clay will not decompose into soil containing gravel 1 4 3 8 GRVE_ABNDNC This field provides an estimate of the abundance of gravel in t
32. geologist s descriptions of the finest grained component of the parent material See appendix 2f for dictionary 1 4 3 2 MAX GRAIN This is a qualitative classification of the largest grain size to be expected from the parent material The value is a estimation derived from geologist s descriptions of the largest grained component of the parent material See appendix 2f for dictionary 1 4 3 3 DOM GRAIN This is a qualitative classification of the most common dominant grain size to be expected from the parent material The value is a estimation derived from geologist s descriptions of the parent material but for heterolithic or mixed lithologies this is difficult to estimate consistently and so is classified as a default unknown See appendix 2f for dictionary 10 1 4 3 4 GEN_GRAIN A geological description and qualitative classification of the grain sizes expected for this parent material based upon the information in the minimum maximum and dominant grain size fields See appendix 2g for dictionary 1 4 3 5 SOIL_TEXT This field provides a general pedological classification of soil texture from measured samples of soils overlying this parent material Soil texture classes are based a UK classification of soil texture designed by The National Soil Research Institute Hodgson 1997 A ternary grainsize distribution chart depicting the classes is given in Appendix 3 Soil samples used to create this classification are derived
33. he soil parent material See appendix 21 for dictionary 1 4 4 Parent material database Mineralogy The parent material database provides five fields of qualitative data for mineralogy these are 1 4 4 1 MINERALOGY This is a free format list of the main minerals to be found in the parent material 1 4 4 2 DOM MNRL This field is a very simplified classification of the dominant mineralogy of the parent material dividing the parent into broad chemical groups For example silica rich carbonate rich acid igneous basic Igneous See appendix 2j for dictionary 11 1 4 4 3 MNR_MNRL These are a free format list of minerals observed in the parent that may affect soil chemistry these include C Carbonate Py Iron sulphides P Phosphate F Iron oxides g Glauconite gy Gypsum etc See appendix 2k for dictionary 1 4 4 4 CACO3_RANK This field classifies all forms of carbonate content in each parent material calcite dolomite siderite as a simple ranking of none low medium or high with unknown or variable for heterolithic and multilithic parent units As a general rule soils forming over carbonate rich rocks tend to have a high carbonate soil chemistry and they are buffered for alkalinity by the underlying parent See appendix 21 for dictionary 1 4 4 5 CACO3_FORM This field details the form in which any carbonate is present in the parent material ranging from nodules shells and clasts to disseminated ceme
34. here bedrock is at surface the LEX ROCK code will be the same as A LEX ROCK and B LEX ROCK codes However for areas where the surface unit is a superficial unit and is potentially thin or a veneer this code can be used to offer an alternative parent material type i e the superficial deposits are locally thin enough to be subject to influence from the characteristics of the underlying bedrock 1 4 10 Parent material database Metadata The parent material database provides six fields of metadata associated with the scale and associated base mapping of each map object these are 1 4 10 1 SHEET This field provides the name and number of the 1 50 000 scale geological sheet that the map object was originally surveyed on 1 4 10 2RELEASED This field is the year of release of the geological sheet that the map object was originally surveyed on 1 4 10 3NOM SCALE This field describes the nominal x y spatial scale of the data Most geological map data in the soil parent material database is captured and presented at a scale of 1 50 000 1 4 10 4NOM BGS YR This field is the year of survey of the 1 50 000 scale geological sheet that the map object was originally surveyed on 1 4 10 5 VERSION This field is the version number of DiGMapGB 50 data used to create the map object 14 1 4 10 60S_SHEET This field is the Ordnance Survey 100km sheet name that underlies the map object 15 DATA LIMITATIONS The soil parent material d
35. ice and provided the local knowledge so important to the description of soil parent materials Key staff have helped to review draft chapters of this report Of the many individuals who have contributed to the project we would particularly like to thank the following Prof B Smith formerly of BGS Dr N S Jones formerly of BGS The author would like to thank Ms F Billin Contents FOREWORD ACKNOWLEDGEMENTS CONTENTS 1 BACKGROUND 1 1 What is a Soil Parent Material 1 2 Technical Information 1 2 1 Data scale and scope 1 2 2 Data origin 1 2 3 Data format 1 3 Who should use the Soil Parent Material dataset 1 4 Using the PMM 1 4 1 Parent material database Map unit description 1 4 2 Parent material database Lithological descriptions 1 4 3 Parent material database Texture descriptions 1 4 4 Parent material database Mineralogy 1 4 5 Parent material database Strength and structure 1 4 6 Parent material database Colour 1 4 7 Parent material database Variability 1 4 8 Parent material database Code only versions of data 1 4 9 Parent material database Alternative DiGMapGB 50 Lex rock descriptors 1 4 10 Parent material database Metadata 1 5 Data Limitations 1 6 Data history 2 CONTACT INFORMATION Appendix 1 A brief overview of the relationship between Soils and parent materials Appendix 2 Dictionaries used in the national soil parent material database 2a EISB_CODE EUROPEAN SOIL BUREAU CODES 2b SUBST
36. ional and regional databases held by BGS primarily DiGMapGB 50 V4 16 The data provides national coverage for England Scotland and Wales at a scale of 1 50 000 The PM database is a growing and developing database which will extend its attribute content to hold enhanced and additional information on near surface properties of rocks superficial deposits and soils over time 1 2 2 Data origin The spatial content of the map is derived from the BGS 1 50 000 scale Geological Map of Great Britain known as DiGMapGB 50 British Geological Survey 2007 with qualitative attribution derived from the BGS Rock Classification Scheme Volumes 1 4 Gillespie and Styles 1999 Robertson 1999 Hallsworth and Knox 1999 McMillan and Powell 1999 and additional soil texture data from the BGS GBASE survey Ault and Mackenzie 2006 1 2 3 Data format The data is supplied as vector GIS layers either in Shape format suitable for ESRI GIS systems or TAB format suitable for MapInfo GIS systems Other formats are available on request The data is also supplied with an example ESRI Map document PM4 MXD file or MapInfo workspace PM4 WOR file to help familiarise users with the data content and its potential use These files can be opened in their respective GIS software and will provide a series of map images coloured and classified to highlight some of the data content 13 WHO SHOULD USE THE SOIL PARENT MATERIAL DATASET Anyone working in the field of env
37. ironmental science from ground engineering to climate change impact assessment can use the soil parent material dataset The dataset has been designed for a diverse user base and simply presents BGS geological and pedological spatial data in a manner that is more flexible for GIS aware environmental scientists A basic understanding of geology and soils is recommended so that users can fully utilise the dataset but any user with a grasp of physical geography should be able to work with the dataset The database sets out simplified qualitative descriptions of PM characteristics Drawing together these characteristics in a meaningful way will allow users to create maps of likely soil and ground environment characteristics More expert users will be able to integrate the parent material dataset into climate land use and terrain data to create full digital soil models For background information on the relationship between soils and parent materials and the use of environmental data in building digital soil models please see Appendix 1 14 USING THE PMM The following sections outline the structure and content of the Soil Parent Material PM database For each of the attribute fields provided in the PM a brief description of the data is given Attribute fields marked with an asterisk also have a lookup dictionary available in Appendix 2 to help users understand the meaning of codes or definitions The parent material database comprise
38. models 17 Appendix 2 Dictionaries used in the national soil parent material database 2A EISB_CODE EUROPEAN SOIL BUREAU CODES The list of parent materials given below has evolved from number of approximations using experiences from several pilot projects The current version includes for the first time a fourth level i e that of the subtype To facilitate the correlation of national geological data to the list below the list of parent materials is preceded by a table that gives for each of the four levels in the classification the criteria used for subdivision To allow for maximum informative value within the major classes criteria for subdivision were different between some major classes Dictionary extracted from P Finke et al 2001 Major Class Group Type Subtype 100 Consolidated 110 psephite or 111 conglomerate 1111 pudding stone clastic rudite sedimentary 112 breccia rocks 120 psammite or 121 sandstone 1211 calcareous sandstone arenite 1212 ferruginous sandstone 1213 clayey sandstone 1214 guartzitic sandstone orthoguartzite 1215 micaceous sandstone 1216 feldspathic sandstone 122 arkose 123 greywacke 1231 feldspathic greywacke 130 pelite agillite 131 claystone 1311 kaolinite bentonite lutite or 132 mudstonesiltst 1312 one 140 facies rocks 141 flysch molasse 1411 sandy flysch clayey bound 142 1412 and silty flysch 1413 conglomeratic flysch 200 Sedimentary 210 calcareous 211
39. n databases of national scale exist for climate land use and relief The parent material database compliments these by providing information detailing the physical characteristics of the soil soil parent materials control three key soil characteristics 1 Texture 2 Mineralogy and therefore Chemistry 3 Permeability Porosity drainage three characteristics are implicitly defined in geological rock deposit descriptions but are easier to use when explicitly defined as in the soil parent material database Texture is regarded as the most important factor For many users it is important to determine soils that are likely to be clay prone heavy from sand prone Light most productive soils tend to be loams i e soils with a mixture of clay silt and sand sized fractions Gravel stone pebble content is also a crucial factor in soil characterisation as gravel improves soil drainage and occludes water The soil parent material database provides a range of texture classifications based upon the lithology of the parent as well as information about likely gravel content derived from observations of gravel content within the parent and the likelihood of the parent forming gravel due to its hardness Mineralogy of parent materials plays a crucial role in soil formation in terms of residual mineralogy during the weathering process and resultant soil chemistry Many soils are defined the presence of important if relatively
40. nts and beds Limestones and chalks are classified as host signifying that the whole parent comprises carbonate material The form of the carbonate is a useful indicator as to how likely a soil will retain some carbonate content a parent with a low nodular carbonate content may weather to a soil type with no residual carbonate See appendix 2m for dictionary 1 4 5 Parent material database Strength and structure The parent material database provides five fields of qualitative data for strength and structure The strength of the parent material will influence how easily it weathers to form a soil and whether the soil will contain gravel or be influenced by the fabric of the underlying parent material The structure of the deposit will provide indicators of how the unit will decompose into constituent components 1 4 5 1 HARDNESS This field is a very simple classification of the parent material into three categories soft hard and very hard As a general guide soft materials will form soils by disaggregating into clay silt or sand grade particles Hard soils may also form sporadic gravel and these will become abraded and rounded with time Very Hard parent materials will form soils with abundant gravel and these may be angular See appendix 2n for dictionary 1 4 5 2 STRNGTH MN This field provides classification of the minimum engineering strength of a map unit See appendix 20 for dictionary 1 4 5 3 STRNGTH MX
41. ode representing a combination of physical characteristics Several systems for classifying parent material exist across the world most classification systems are simplified subsets of geological descriptions of rock units Many systems are flawed in that the PM classification relies on inconsistent grouping of certain geological characteristics i e some PM classification systems are based on rock genesis others are based on knowledge of texture The BGS PM classification is based upon the primary origin of the material its dominant mineralogy and its generalised texture grain size see figure 1 below Most users will find the PM codes are sufficient to describe the parent materials and their likely soil characteristics However by using combinations of data held in the other attribute fields of the dataset users can create a range of parent material maps varying in complexity from simplistic to detailed offering a number of classifications The PM database provides three key PM codes to describe each map objects these are PM CODE A PM CODE and PM CODE see below for details These codes are all four character composite codes and all have the following structure Code SCQA SC Q A First two characters Third character Last character represent the represents the Represents the origin of the parent ie dominant mineralogy General grainsize code Sedimentary Clastic code Silica clay Argillaceous Figure
42. reasonable length without prior permission provided a full acknowledgement is given of the source of the extract Maps and diagrams in this book use topography based on Ordnance Survey mapping NERC 2009 All rights reserved Keyworth Nottingham British Geological Survey 2009 BRITISH GEOLOGICAL SURVEY The full range of our publications is available from BGS shops at Nottingham Edinburgh London and Cardiff Welsh publications only see contact details below or shop online at www geologyshop com The London Information Office also maintains a reference collection of BGS publications including maps for consultation We publish an annual catalogue of our maps and other publications this catalogue is available online or from any of the BGS shops The British Geological Survey carries out the geological survey of Great Britain and Northern Ireland the latter as an agency service for the government of Northern Ireland and of the surrounding continental shelf as well as basic research projects It also undertakes programmes of technical aid in geology in developing countries The British Geological Survey is a component body of the Natural Environment Research Council British Geological Survey offices BGS Central Enquiries Desk Tel 0115 936 3 email Fax 0115 936 3276 enquiries Obgs ac uk Kingsley Dunham Centre Keyworth Nottingham NG12 5GG Tel 0115 936 3241 Fax 0115 936 3488 email sales bgs ac uk Murchison
43. rric peat 812 groundwater fed bog peat 820 slime and ooze 821 gyttja sapropel deposits 830 carbonaceaous 831 lignite brown rocks coal caustobiolite 832 hard coal 833 anthracite 900 Anthropogenic 910 redeposited 911 sand and gravel deposits natural fill materials 912 loamy fill 920 dump deposits 921 rubble rubbish 922 industrial ashes and slag 923 industrial sludge 924 industrial waste 930 organic materials 21 2b SUBSTRATE PM_DIC_SUBSTRATE SUPERFICIAL UN IT IS CLASSED AS A SUPERFICIAL DEPOSIT L UNIT IS CLASSED AS A SUPERFICIAL DEPOSIT WITH A THIN SURFICIAL FORM VENEER 22 2 ORIGIN_PM PM_DIC_CORE_LITHOTYPE SEDIMENTARY Rocks of sedimentary origin 23 2D ROOT_PM PM_DIC_ROOT_LITHOLOGY ROO TCO ROOT_LITHOLOGY DEFINITION DE AX ARTIFICIAL DEPOSITS OR DISTURBED UNITS IE IGN EXTRUSIVE EXTRUDED IGNEOUS ROCK II IGN INTRUSIVE INTRUDED IGNEOUS ROCK IM IGN MINERALISATION INJECTED MINERALIS ATION ASSOCIATED WITH IGNEOUS ACTIVITY IP IGN VOLCANOCLASTIC IPYROCLASTIC VOLCANOCLASTIC IGNEOUS ROCK IT IGN VOLCANOCLASTIC TUFFACEOUS VOLCANOCLASTIC IGNEOUS ROCK IX IGN_MIXED IGNEOUS ROCK MIXED GENESIS MC META SED CLASTIC METAMORPHOSED SEDIMENTARY CLASTIC ROCKS ME META IGN EXTRUSIVE IMETAMORPHOSED IGNEOUS EXTRUSIVE ROCKS MI IGN INTRUSIVE IMETAMORPHOSED IGNEOUS INTRUSIVE ROCKS MK META SED CARBONATE CLAS METAMORPHOSED
44. s a spatial layer a map of polygons with each map unit being described by fifty three fields of attribute data Most fields are populated with plain text simple text descriptions are used as they are considered more user friendly to non specialists however some fields are populated with codes for ease of use within a GIS The general structure of the attribute data is shown in Table 1 below Table 1 General attribute content of the PM database Fields Content Fields 1 2 ESRI shapefile identifiers not applicable for non ESRI formats Fields 3 10 Map Unit Descriptors e g PM codes unique id Fields 11 20 Lithological descriptors e g parent rock type Fields 21 28 Texture descriptors e g soil texture Fields 29 33 Mineralogical descriptors e g CaCO3 content Fields 34 38 Strength and structure descriptors e g Hardness Fields 39 40 Colour descriptors e g fresh colour Fields 41 variability descriptor Fields 42 47 Coded versions of selected descriptors e g Agecode Fields 48 49 Alternate DiGMapGB 50 descriptors e g alternative Lex rock classification Fields 50 55 Map metadata e g version number 1 4 1 Parent material database Map unit description Each map unit polygon is described by eight fields detailing its parent material type and the near surface spatial context of the unit The parent materials are described by a series of codes each c
45. t for Farming and Rural Affairs PB11160 http www rpa gov uk rpa index nsf vContentByTaxonomy B0282EE0A3104193802570D1005AC787 OpenDocument 42
46. tinuum with no distinctive point of transition The major soil groups in the UK are distinguished by broad differences in the composition or origin of the soil material Avery 1979 Soil parent materials play a vital role in determining soil type Typically parent material characteristics control three primary characteristics of their overlying soils 1 Texture 2 Chemistry 3 Permeability Porosity drainage All three characteristics are implicitly defined in the typical geological rock deposit descriptions provided in BGS products However these characteristics are easier to use by non geologists when explicitly defined as they are in the soil parent material database Most users will use the soil parent material data as their core data source to help them model and understand soil characteristics Other datasets for terrain analysis climate and landuse will help the user to build true digital soil models BGS also supplies specific data for slope accumulation wind blown deposits cover artificial deposits and geochemistry if users are particularly interested in thickened soil profiles soil erosion mobilisation gleying or unusual soil geochemical profiles The soil parent material data has attributes for the following characteristics Lithology Texture Mineralogy Strength Structure Colour Age Variability 12 TECHNICAL INFORMATION 1 2 1 Data scale and scope The PM database is a synthesis of several nat
Download Pdf Manuals
Related Search