Note that in older geological works predating theories of , the ' Catskill Delta formation is sometimes referred to as part of the Old Red Sandstone. In the modern day, however, it is recognized that the two are not stratigraphically continuous but are very similar due to being formed at approximately the same time by the same processes.
The Old Red Sandstone has been widely used as a building stone across those regions where it outcrops. Notable examples of its use can be found in the area surrounding Stirling , , , and . The inhabitants of at the northeastern tip of Scotland also used the stone to a considerable extent. Old Red Sandstone has also frequently been used in buildings in , and the former (now south ) of south .
In the early 19th century, the paleontology of the formation was studied intensively by , , , and -- Sedgwick's interpretation was the one that placed it in the : in fact it was he who coined the name of that period. The term 'Old Red Sandstone' was originally used in 1821 by Scottish naturalist and mineralogist to refer to the red rocks which underlay the 'Mountain Limestone' i.e. the Carboniferous Limestone. They were thought at that time to be the British version of Germany's Rotliegendes, which is in fact of age. Many of the of 's early debates were about the Old Red Sandstone.
The oldest part of the Old Red Sandstone that yields fossil fish is the Cowie Harbour Fish Bed, which is exposed along the foreshore between Stonehaven and the small village of Cowie to the northeast. This is part of the Midland Valley portion of the Old Red Sandstone and is Silurian in age. Fossils are found in fine-grained shales and mudstones in between layers of sandstone. While the fossils of the freshwater crustacean Dictyocaris are common enough, fossil fish are very rare indeed. I can recall collecting from this formation several times, while studying at nearby Aberdeen University, and never once found any fish remains.
Excerpt from Hugh Miller's The Old Red Sandstone (1841)