Mudstone and Sandstone, County Down

Capped by a layer of basalt that protected it from erosion, the sandstone that makes up most of Scrabo hill has been quarried and used for building stone. In the quarry itself, basalt sills and dykes can be seen cutting the sandstone; they were formed about 60 million years ago, whilst the sandstone itself is over 200 million years old.

The layers of red sandstone and mudstone found here were formed in desert conditions; some of the sands show cross-bedding formed by wind-blown dunes, whilst mudstone layers occasionally show cracks that formed as the mud dried out after occasional rainstorms. More evidence for a desert environment comes from the recent discovery of scorpion prints at this site.

Credit: Alex Donald

Credit: N. Ireland Environment & Heritage Service