The
Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of
Devonian age. It extends in the east across
Britain,
Ireland and
Norway and in the west along the northeastern seaboard of
North America. It also extends northwards into
Greenland and
Svalbard. In Britain it is a
lithostratigraphic unit (a sequence of
rock strata) to which
stratigraphers accord supergroup status and which is of considerable importance to early
paleontology. For convenience the short version of the term,
ORS is often used in literature on the subject. The term was coined to distinguish the sequence from the younger
New Red Sandstone which also occurs widely throughout Britain.