Geology

The geology of the county can be divided in two – a northern upland region with older, Ordovician and Silurian rocks of slate, shale, sandstone and greywacke – about 450 to 420 million years old. In the southern lowland region younger Carboniferous rocks of limestone – about 350 to 330 million years old, are the most common rock types in the county.                               

In the 1960s and 1970s, mining companies discovered the Keel deposit of zinc sulphide and lead sulphide. There was insufficient commercial quantity and the mine closed down.                                                                                                                               

The soil of the county is very varied changing from a light thin mould in the north- west to deep loamy clay in the south.
 

Cairn Hill

Cairn Hill, 916 feet, is the highest point in County Longford. It is crowned by a pre historic cairn and offers an extensive view of the Central Plain on a clear day. An RTE mast is now sited on its summit.                                                                                                                           

Natural Heritage Areas

The bogs of Aghamona, Cloonageeher, Forthill, and Mt. Jessop, are designated NHA areas in the county. Special areas of conservation (SAC) protect habitats of community interest (raised and active blanket bogs, turloughs, lakes and rivers) and also aims to protect animal and plant species (bats, salmon, white clawed crayfish.) These are found in Longford including the Lough Ree and Lough Forbes complex.