Giffnock Sandstone is a Carboniferous sandstone from the Glasgow area. During the Carboniferous Scotland was located close to the equator and experienced tropical conditions. In the Midland Valley Region sands, silts and muds were deposited under deltaic conditions and it was from these that Giffnock Sandstone eventually formed. Giffnock is described as a ‘freestone’ because of its textural uniformity and as such is often seen as dressings and carved detail on buildings. Quarrying finished at the end of the 19th Century.
Giffnock is fine to medium-grained and when fresh is buff coloured with specks of darker mineral grains visible. Exposure results in oxidation of iron minerals in the stone surface forming a hardened rust-brown outer layer. if this layer is breached, decay of the underlying sandstone may proceed rapidly.