Ballagh ASSI

Ballagh is a special place because of its earth science interest. The disused quarry provides access to Carboniferous age sedimentary rocks for which the sequence at Ballagh is the reference site for the Ballagh Limestone Member.

This site is of geological importance because the rocks at Ballagh define a geological unit, the Ballagh Limestone Member which forms part of the more widespread Dartry Limestone Formation. These rocks are of Carboniferous age, the geological period that lasted from 354 to 290 million years ago. During much of this period, what is now Northern Ireland was covered by fairly shallow tropical waters.

The rock at Ballagh is a very coarse limestone full of crinoid remains. Crinoids, or sea lilies, are marine animals which often lived in shallow marine conditions and were attached to the sea bottom by a stalk. Fragments of these stalks are abundant in the limestone here. Other shell fragments can be found including brachiopod or lampshell fragments.