What’s That? Your Search Plan Explained

1: Adit

What’s on my Search Plan, and what does it mean?

The plan that accompanies every one of our mining searches can carry a lot of information, particularly in the heavily mined areas of the United Kingdom. In this series of posts we’ll be taking a look at what can appear on a search plan, and what it means.


An adit is a horizontal or nearly horizontal tunnel for working or draining a mine, and can also be called a drift or a sough – depending on where you are in the country. Adit levels can be deep or shallow and are generally the lowest level from which water can be drained.

Drainage was essential for mines where workings went below the natural water table; below this depth, continuous pumping would be required to keep everything dry. By utilising an adit for drainage, the distance water has to be pumped is reduced from the surface to just above the water table. As long as the adit remains open, any workings above the adit level will naturally drain.

Adits can also identify unknown mineralised veins to exploit, which can in part fund their cost. An example of this can be found in Derbyshire in the form of the Meerbrook Sough which, at a little over 6.5 kilometres, intersected a number of previously unknown lead veins. In one 260 metre section, three veins were identified and later worked.

An outstanding example is the Great County Adit in Cornwall. Work commenced in 1748 and its extensive network of tunnels eventually drained over 100 mines, with its total length estimated to be over 65 kilometres and its average depth was approximately 100 metres. In 1839 the Great County Adit was thought to be discharging approximately 66 million litres of water a day.

So if an adit appears on your search plan, what does it mean? The Past Metalliferous Mining Activity section will explain all – whether the adit is deep or shallow and whether it affects your property at surface.