Insight User Guide: Geology 1:50,000 scale

1:50,000 Availability

An indication on the coverage of 1:50,000 scale geology data for the site. Either ‘Full’ or ‘No coverage’ is provided for each geological theme. The map will only display sheet edges. If the site is in the centre of a map sheet it may appear blank. ‘Full’ coverage indicates all derived layers are available for the site, and ‘No coverage’ indicates that no layers are available for the area.

Artificial and made ground (1:50,000)

Details of made, worked, infilled, disturbed and landscaped ground at 1:50,000 scale. Artificial ground can be associated with potentially contaminated material, unpredictable engineering conditions and instability. Artificial ground is a term used by BGS for those areas where the ground surface has been significantly modified by human activity.

The artificial ground theme includes:

• Made ground — man-made deposits such as embankments and spoil heaps on the natural ground surface

• Worked ground — areas where the ground has been cut away such as quarries and road cuttings

• Infilled ground — areas where the ground has been cut away then wholly or partially backfilled

• Landscaped ground — areas where the surface has been reshaped
• Disturbed ground — areas of ill-defined shallow or near surface mineral workings where it is impracticable to map made and worked ground separately.
  
  

Superficial geology (1:50,000)

Superficial geological deposits at 1:50,000 scale. Superficial deposits (formerly known as ‘drift’ by the BGS) are the youngest geological deposits formed during the most recent period of geological time, the Quaternary, which extends back about 2.6 million years from the present.

Superficial permeability

A qualitative classification of estimated rates of vertical movement of water from the ground surface through the unsaturated zone of any superficial deposits (the zone between the land surface and the water table).

Artificial Ground Permeability

A qualitative classification of estimated rates of vertical movement of water from the ground surface through the unsaturated zone of any artificial deposits (the zone between the land surface and the water table).

Landslip (1:50,000)

Mass movement deposits on BGS geological maps at 1:50,000 scale. Primarily superficial deposits that have moved down slope under gravity to form landslips. These affect bedrock, other superficial deposits and artificial ground.

Landslip permeability

A qualitative classification of estimated rates of vertical movement of water from the ground surface through the unsaturated zone of any landslip deposits (the zone between the land surface and the water table).

Bedrock geology (1:50,000)

Bedrock geology at 1:50,000 scale. Bedrock geology (formerly known as ‘solid’ geology by the BGS) is a term used for the main mass of rocks forming the Earth and present everywhere, whether exposed at the surface in outcrops or concealed beneath superficial deposits or water. The bedrock has formed over vast lengths of geological time ranging from ancient and highly altered rocks of the Proterozoic, some 2500 million years ago, or older, up to the relatively young Pliocene, 2.6 million years ago.

Bedrock permeability

A qualitative classification of estimated rates of vertical movement of water from the ground surface through the unsaturated zone of bedrock (the zone between the land surface and the water table).

Bedrock faults and other linear features (1:50,000)

Linear features at the ground or bedrock surface at 1:50,000 scale of six main types; rock, fault, fold axis, mineral vein, alteration area or landform. Features are either observed or inferred, and relate primarily to bedrock. Printed paper maps may also show other ‘concealed’ linear features such as faults or coal seams on the ‘sub-Triassic’ surface, i.e. the assumed outcrop of these features (probably identified in coal mines or boreholes) projected on the unconformity below Triassic strata. These underground features are not included in the BGS Geology linear theme in order to minimise the potential confusion they could cause to users if interpreted wrongly as being in overlying bedrock strata at the surface or just beneath superficial deposits.

The linear geological features are grouped into seven categories:

Category	Description
Rock	Lines representing thin beds of notable geological materials e.g. Coal, gypsum, ironstone, marine bands or fish beds. Relevant to the Bedrock theme.
Fault	Lines representing planes of structural movement such as: normal faulting or thrusts. Relevant to the Bedrock theme.
Mineral vein	Lines representing the surface expression of mineralised fractures/veins. Relevant to the Bedrock theme.
Fold axis	Lines representing planes of structural change/symmetry such as: anticline or syncline. Relevant to the Bedrock theme.
Alteration area	Lines that represent the spatial limit of alteration e.g. metamorphic aureoles or vein swarms. Relevant to the Bedrock theme.
Landform	Lines that represent landform features e.g. dune crestline or channel margin. Relevant to all themes and topography.