The Aquifer Geological Lines shows the details of the structural geology; faults and thrusts. Faults are the result of great pressure being applied to rock across a whole continent or more. These rocks break under the pressure, forming faults. Faults are recorded as lines where the break in the rock meets the surface. A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks.

Geologists map and record information on the composition and structure of rock outcrops (rock which can be seen on the land surface) and boreholes (a deep narrow round hole drilled in the ground). Lines are drawn on a map to show the structure.

To produce this dataset, the twenty one 1:100,000 paper maps covering Ireland were digitised and any inconsistencies between map sheets were fixed. We collect new data to update our map and also use data made available from other sources.

This map is to the scale 1:100,000 (1cm on the map relates to a distance of 1km).

It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas).

The Geological Lines data is shown as lines. Each line holds information on: description of the line, bedrock 100k map sheet number, line code and name (if it has one).