The Old Red Sandstone is a dark red sandstone laid down mainly in the Devonian period over a large part of the continent of Laurussia. The base of the ORS is now known to be in the Silurian and the top in the Carboniferous.[2]
Laurussia is often called the Old Red Continent, or Euramerica. It included what is now much of northern Europe, Greenland and North America. It was, at the time, between 0o and 30o south of the equator.
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