Linear features (shown as polylines) represent seven 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). The scale of the data is 1:10 000 and 1:25 000 scale. Onshore coverage is partial with approximately 52% of England, Scotland, and Wales available in the version 3 data release. BGS intend to continue developing coverage at this scale; current focus is to include all large priority urban areas, along with road and rail transport corridors. 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 Axis: 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 horizon: 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. Landforms: define the landscape by its surface form; these include glacial features such as drumlins, eskers, and ice margins. Mineral vein: where concentrations of crystallised mineral occur within a rock, they are closely associated with faulting, but may occur independently. Rock: lines representing beds of notable geological materials and key marker beds, e.g., coal, gypsum, ironstone relevant to the Bedrock theme. 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.
