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

Data identifying landscape areas (shown as polygons) attributed with geological names. The scale of the data is 1:50 000 scale. Onshore coverage is provided for all of England, Wales, Scotland and the Isle of Man. Data are supplied as five themes: bedrock, superficial deposits, mass movement, artificial ground and linear features. Bedrock geology describes the main mass of solid rocks forming the earth’s crust. Bedrock is present everywhere, whether exposed at surface in outcrops or concealed beneath superficial deposits or water bodies. Geological names are based on the lithostratigraphic or lithodemic hierarchy. The lithostratigraphic scheme arranges rock bodies into units based on rock-type and geological time of formation. Where rock-types do not fit into the lithostratigraphic scheme, for example intrusive, deformed rocks subjected to heat and pressure resulting in new or changed rock types; then their classification is based on their rock–type or lithological composition. This assesses visible features such as texture, structure, mineralogy. Superficial deposits are younger geological deposits formed during the most recent geological time; the Quaternary. These deposits rest on older rocks or deposits referred to as bedrock. The superficial deposits theme defines landscape areas (shown as polygons) attributed with a geological name and their deposit–type or lithological composition. Mass movement describes areas where deposits have moved down slope under gravity to form landslips. These landslips can affect bedrock, superficial or artificial ground. Mass movement deposits are described in the BGS Rock Classification Scheme Volume 4. However this data also includes foundered strata, where ground has collapsed due to subsidence (this is not described in the Rock Classification Scheme). Caution should be exercised with this data; historically BGS has not always recorded mass movement events and due to the dynamic nature of occurrence significant changes may have occurred since the data was released. Artificial (man-made) theme (shown as polygons) indicates areas where the ground surface has been significantly modified by human activity. Whilst artificial ground may not be considered as part of the 'real geology' of bedrock and superficial deposits it does affect them. Artificial ground impacts on the near surface ground conditions which are important to human activities and economic development. Due to the constantly changing nature of land use and re-use/redevelopment, caution must be exercised when using this data as it represents a snapshot in time rather than an evolving picture hence the data may become dated very rapidly. Linear features (shown as polylines) represent 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. Landform elements are associated with both bedrock and superficial deposits. All five data themes 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.

本数据集用于识别赋予地质名称的景观区域（以多边形要素表示），比例尺为1:50000。其陆上覆盖范围涵盖英格兰、威尔士、苏格兰及马恩岛全境。数据集包含5个数据主题：基岩、表层沉积物、块体运动、人工地表与线性要素。

基岩地质指构成地壳的主要固体岩体。基岩遍布全域，既可出露于地表形成露头，也可被表层沉积物或水体覆盖。

地质名称基于岩石地层（lithostratigraphic）或岩石体地层（lithodemic）分级体系。岩石地层分类方案依据岩石类型与形成地质时代，将岩体划分为不同单元。若岩石类型无法归入岩石地层分类方案（如侵入岩、经热压作用形成新的或改变后岩性的变形岩石），则以岩石类型或岩性组成作为分类依据，该分类通过评估纹理、结构、矿物学特征等可见属性实现。

表层沉积物是形成于最新地质时代——第四纪（Quaternary）的年轻地质堆积物，覆于被称为基岩的老岩体或沉积物之上。表层沉积物主题定义了赋予地质名称及沉积物类型/岩性组成的景观区域（以多边形要素表示）。

块体运动指沉积物在重力作用下沿斜坡移动形成滑坡的区域，此类滑坡可影响基岩、表层沉积物或人工地表。块体运动沉积物的相关描述见于英国地质调查局（BGS）《岩石分类方案第4卷》，但本数据集还包含因地面沉降导致地层陷落的内容（该类情况未被纳入上述岩石分类方案）。

使用本数据集时需谨慎：历史上英国地质调查局（BGS）并非始终记录所有块体运动事件，且由于该类现象的动态性，数据集发布后可能已发生显著变化。

人工地表（即人为改造地表）主题以多边形要素表示，指代地表经人类活动显著改造的区域。尽管人工地表通常不被视为基岩与表层沉积物这类“真实地质”的组成部分，但它会对二者产生影响。人工地表会改变近地表地质条件，这对人类活动与经济发展至关重要。

由于土地利用、再利用及再开发的持续变化性，本数据集仅为某一时刻的快照，而非动态演化的全貌，因此可能快速过时，使用时需格外谨慎。

线性要素以多段线（polylines）要素表示，指代地质构造特征（如断层、褶皱）或地貌特征（如埋藏河道、覆盖于表层沉积物之下的冰川排水河道，或地表/基岩表面的冰川排水河道）。线性要素与基岩主题关联最为紧密：既可以是基岩的固有组成部分（如海相层），也可如断层般对基岩产生影响。地貌要素则同时与基岩和表层沉积物相关联。

全部五个数据主题均以矢量格式（包含与属性描述数据库记录关联的各要素几何信息）提供，格式为ESRI形状文件（ESRI shapefiles），可依据英国地质调查局（BGS）数据许可协议获取。