Corsehill Sandstone is part of the New Red Scottish Triassic Sandstone group formed some 250 million years ago. It was a popular building stone in the 19th and early 20th Centuries and is still quarried near Annan. Corsehill is fine to medium grained and composed of cemented mineral grains including quartz, feldspars, mica and iron-rich minerals such as haematite, all of these grains are coated in reddened iron-rich clays.
This sandstone also contains clearly defined bedding/lamination structures where clay minerals are concentrated. Although Corsehill is quite durable and tends to weather by granular disintegration it is prone to delamination if face-bedded and has a high porosity of around 28%.