Digital Geological Map Data of Great Britain - 50k (DiGMapGB-50) Linear version 7

Linear features (shown as polylines) represent six classes of geological structural features e.g. faults, folds or landforms e.g. buried channels, glacial drainage channels at the ground or bedrock surface (beneath superficial deposits). Linear features are associated most closely with the bedrock theme either as an intrinsic part of it for example marine bands or affecting it in the case of faults. However landform elements are associated with both bedrock and superficial deposits. The linear features are organised into seven main categories: Alteration area indicating zones of change to the pre-existing rocks due to the application of heat and pressure that can occur round structural features such as faults and dykes. Fault where a body of bedrock has been fractured and displaced by a large scale process affecting the earth's crust. Fold where strata are bent or deformed resulting from changes or movement of the earth's surface creating heat and pressure to reshape and transform the original horizontal strata. Folds appear on all scales, in all rock types and from a variety of causes. Fossil horizons where prolific fossil assemblages occur and can be used to help establish the order in which deposits were laid down (stratigraphy). These horizons allow correlation where sediments of the same age look completely different due to variations in depositional environment. Mineral vein where concentrations of crystallised mineral occur within a rock, they are closely associated with faulting, but may occur independently. Landforms define the landscape by its surface form; these include glacial features such as drumlins, eskers and ice margins. Rock identifies key (marker) beds, recognised as showing distinct physical characteristics or fossil content. Examples include coal seams, gypsum beds and marine bands. The data are available in vector format (containing the geometry of each feature linked to a database record describing their attributes) as ESRI shapefiles and are available under BGS data licence.以折线（polylines）表示的线性要素涵盖六类地质构造特征（如断层（fault）、褶皱（fold））与地貌形态（如埋藏河道、地表或基岩表面（浅覆沉积物之下）的冰川排水河道）。线性要素与基岩主题关联最为紧密，既可作为其固有组成部分（如海相层），也可如断层一般对基岩产生改造作用。不过地貌要素同时与基岩和浅覆沉积物相关联。本次数据集的线性要素共分为七大类别：1. 蚀变区域（Alteration area）：指因热与压力作用（常发育于断层、岩脉（dyke）等构造特征周边）使原有岩石发生改变的区域。2. 断层（Fault）：指受影响地壳的大规模构造作用导致基岩岩体发生破裂与位移的地质构造。3. 褶皱（Fold）：指因地表变化或运动产生热与压力，使原始水平地层发生弯曲或变形的构造。褶皱规模不一、发育于各类岩石中，成因多样。4. 化石层位（Fossil horizons）：指产出大量化石组合的地层，可用于确定沉积物的沉积顺序（地层学（stratigraphy））。当相同时代的沉积物因沉积环境差异外观迥异时，可借助此类层位开展地层对比。5. 矿脉（Mineral vein）：指岩石中结晶矿物富集的区域，虽常与断层作用密切相关，但也可独立产出。6. 地貌（Landforms）：指以地表形态塑造景观的要素，包括鼓丘、蛇形丘、冰缘等冰川地貌。7. 标志岩层（Rock）：指具有独特物理特征或化石含量的关键（标记）地层，例如煤层、石膏层与海相层。本数据集以矢量格式（vector format）提供，包含各要素的几何信息，并与描述其属性的数据库记录相关联，格式为ESRI形状文件（ESRI Shapefile），可按照英国地质调查局（BGS）数据许可协议获取。